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Canine Epilepsy Drug Combination Improves Treatment
Source: Animal News, a publication of Morris Animal Foundation; 45 Inverness Drive East, Englewood, CO 80112-5480. 800-243-2345. Volume III 1999
Epilepsy is a condition resulting in multiple and consistent convulsions. These seizures can be deadly if not treated immediately by a veterinarian.
Scientists aren't certain what causes epilepsy but they are able to treat the convulsions caused by this condition. The most common treatment for these convulsions is phenobarbital or its derivative, primidome.
An owner living with an epileptic dog must be committed to a pet's lifetime of treatment to manage the seizures, provide veterinary supervision and administer regular doses of anticonvulsant medication.
About 40 percent of epileptic dogs don't respond to treatment. This is called refractory epilepsy. Some dogs simply need to have their anticonvulsant dosage increased for it to take effect. Sadly, some pet owners are not aware of this and select to have their pets euthanized becuase they can't manage the disease.
For the past three years, Dawn Merton Boothe, DVM, PhD, at Texas A & M University, has been studying new drugs in combination with the standard treatment of phenobarbital to treat refractory epilepsy.
She has been working with owners and their veterinarians throughout the country studying the effects of several different anticonvulsant medications - felbamate, potassium bromide and clorazespate in combination with phenobarbital in relieving dogs from convulsions. During this time, 61 patients have been enrolled in this study and over 49 have completed the study.
Each patient participated for up to six months, depending on the length of time lapsing between seizures. In addition to tracking the convulsions, owners provided Dr. Boothe with regular blood samples and updates on their pet's condition. Dr. Boothe continues to work with study participants, intensively if needed, for the duration of the animals' lives.
Dr. Boothe will have the final results of her study in early 1996. Preliminary results are encouraging with some dogs showing positive response and fewer convulsions.
This Morris Animal Foundation-sponsored study received the generous support of the Arkansas Veterinary Medical Foundation, Golden Retriever Club of America, Trustee Arlene Klein, Middlesex County Kennel Club, Morris Animal Foundation, Fort Worth/Tarrant County Animal Foundation and the St. Bernard Club of America.
BRANDI'S SEIZURES SUBSIDE
"Brandi hasn't had a seizure in 14 months," exclaims June Ellison of Virginia. Brandi participated in Dr. Dawn Boothe's epilepsy study at Texas A & M.
Brandi, a 6-year-old English springer spaniel, started showing signs of epilepsy when she was two and one-half years old. "My veterinarian, Dr. Mark Vernon at Mont Clair Animal Hospital, read about this study in a newsletter," says June. He suggested that Brandi join the study.
Brandi suffers from refractory epilepsy. Her seizures first appeared about every eight weeks. "Brandi had cluster seizures so she would have to be hospitalized for three to four days. They were grand mal seizures - and they were bad," says June.
"So I called Dr. Boothe to have Brandi participate in the study. She became part of the unknown control group." June wasn't aware of the drug that Brandi took in combination with phenobarbital. She did know it worked. Brandi's seizures occurred further and further apart. The first year after the study, Brandi only had two sets of seizures, and without clusters. She hasn't had a seizure since that time. "Brandi tends to have seizures during warm weather, so I kept waiting. But, she didn't have one this summer. It's been 14 months," June says.
"We've finally hit a happy medium on the drug combination." Now that formal participation in the study is over, June knows that the medication helping Brandi is clorazespate in combination with phenobarbital.
Brandi currently takes five pills a day. June explains: "Brandi knows when it's time to take her medication. She puts both paws on the counter and I pop the pills down her mouth. The she gets treats."
To make certain Brandi gets her daily medication, the Elllisons have a system that works. When they give Brandi her morning pills, they put the remainder of her day's pills in a plastic baggy and attach it with a magnet to the refrigerator. When the baggy is empty at the end of the day, they know Brandi has had all of her medicine. If the baggy is not on the refrigerator when they leave for work, it's a reminder to give Brandi her medicine.
June explains, "Brandi's my baby. She has a productive life and is a member of the family." Her family includes nine other dogs in the Ellison's home.
Original Doc: EPI10.WPD
Epilepsy and Seizures in Dogs
Veterinarian in Attendance
Are They the Same?
By Samuel Hodesson, D.V.M., M.P.H.
Source: Dog News, pp. 30, 116, 120 & 124.
Seizures cause more concern to owners and doctors and less to the patient than many other diseases:
1. Watching a dog undergo a seizure is a frightening experience for anyone, much more for human members of the immediate family. The first thought in the minds of many is that the dog is rabid. Rabies virus can cause seizures but, in my experience, usually doesn't.
2. As with many non-infectious diseases the cause of the problem is difficult for veterinarians to determine and treatment is not always effective.
3. Although extended seizures can cause permanent injury or death, the dog usually remains unconscious during the worst part of the event and comes out of it none the worse for the experience. Many patients are unaware that anything unusual has happened.
Part I of this series of two will concentrate on what goes on in a dog's head just before and during a seizure, terminology, and common causes. The subjects of breeds at risk, treatment, and management with concluding comments will appear in a later issue of Dog News.
"The terms seizure, convulsion, epilepsy and fit are synonyms for a brain disorder expressed as...transitory disturbance of brain function that has a sudden onset, ceases spontaneously and has a tendency to recur. The term epilepsy is more often used for seizures that are recurrent and of unknown cause...." (A. de Lahunta, Veterinary Neuroanatomy and Clinical Neurology, W.B. Saunders Co., page 32, Chapter 18.) Doctor de Lahunta's text provided an excellent source of information for the discussion that follows.
When no brain lesions can be found the term "idiopathic" epilepsy (of unknown cause) is applied. The words "true" or "inherited" are sometimes used in place of "idiopathic."
The nerve cell, called a neuron, is the basic building block of the extremely sophisticated mammalian nervous system. The neuron consists of a cell body and its axon, a fiber of varying length. Students of neuroanatomy estimate that the human nervous system consists of some hundred thousand miles of nerve fibers.
The cell body has an arbor of nerve endings, called dendrites, that connect with endings of other nerve cells. The actual area of transmission of nerve impulses between fiber endings is known as a synapse. When an electrical charge originates in a cell body, it can be transmitted to any one or all of that cell's fiber endings and then to any one or combination of a myriad of other cells across the synapse.
Neurons of the brain control the course of a nerve impulse through the system's network like the automated electronic switchboards of a modern fiber optic telephone system. This impulse conducted through axons of motor neurons can activate muscle fibers causing them to contract.
In an epileptic animal, a spontaneous uncontrolled discharge may occur in one or more neurons of the brain and spread to other neurons. This may induce surrounding nerve cells to discharge and the seizure spreads or generalizes. Resistance to uncontrolled discharge varies somewhat in each individual.
Most seizures in dogs are the generalized type known as grand mal. Observant owners will notice a change in behavior for a brief period during which their pet may become restless, look worried, seek attention or stare into space. Loss of consciousness follows and pupils of the eyes dilate.
Excessive salivation and chewing movements, commonly called chewing fits, may follow. Legs stiffen and the dog falls on its side. Paddling or running movements may alternate with periods of rigid extension of the legs and arching of the back. The patient may urinate or defecate during or after the seizure.
Most attacks last but a minute or two and the recovery period is usually short though it can persist for as much as a day. During this stage the dog may appear confused or wander about and bump into objects in the room.
Inexperienced persons and young children should not attempt to handle a dog during any of the stages of a seizure. These animals are not responsible for their behavior at this time. Some clients felt that wrapping a small dog in a blanket and holding it tight shortened the period of convulsions. Anything that limits the animal's movement decreases risk of self inflicted injury.
Toxic substances such as strychnine, pesticides and lead; changes resulting from heat stroke; and inflammation caused by infection can alter the response of a neuron to an electric charge. When this occurs seizures can result in otherwise normal animals. Fatigue, hyperventilation, fever, estrus, and bright lights can stimulate others to convulse.
A third group consists of individuals who have spontaneous seizures with no external stimulus. These are animals subject to true or idiopathic epilepsy. Their genetic background has predetermined the structure and function of their nervous systems.
The cause of changes in neuron function leading to seizure can originate outside the central nervous system (extracanial). Hypoglycemia is a common extracanial cause. De Lahunta states that Boxers, Poodles and terriers are at highest risk but many of my cases were toy breeds under the age of four months.
Hypoglycemia frequently follows malnutrition or heavy parasitism in puppies but may result from an excessive release of insulin after a feeding. Intravenous or oral doses of fifty percent sugar solution brings immediate response and puppies usually outgrow the problem.
Hunting dogs can develop hypoglycemia following heavy exercise. Some recommend that hunters carry candy bars when working their dogs in the field.
Nursing or pregnant bitches can develop eclampsia, convulsions caused by low blood calcium levels. If not corrected in the early stages, this disease can progress to coma. The history will readily distinguish the problem from epilepsy. In my opinion a lactating bitch with a large litter, wide awake and conscious of its predicament, doesn't look like one with epilepsy.
After many years of preventing reoccurrence of this disease by adding vitamin D and calcium to the diet of the bitch during her next pregnancy, experts now tell us that this practice is contraindicated. It reduces her ability to produce the extra calcium needed immediately after whelping. These recommendations prove that the only thing constant in medicine is that nothing is constant.
Treatment for eclampsia, intravenous calcium gluconate, is specific and almost immediately effective although relapses can occur. The regularly available solutions can cause ugly sloughs if any escapes from the vein; injections should be given by professionals. Vitamin D and calcium are usually added to the bitches diet until the puppies are weaned.
Inflammation of neurons within the brain can result from severe liver disease or infectious processes. Before the development of effective vaccines, distemper virus was the most frequent cause of seizures in dogs. Many a heartbroken client and veterinarian nursed a dog with distemper to an apparently successful conclusion only to euthanatize it when continuous intractable seizures develop.
Toxoplasma, single cell parasites, and fungi such as Cryptococcus can cause seizures when localizing in the brain. Tumors within the skull frequently cause seizures. The slow, relentless progress and other characteristics of this affliction usually differentiate it from epilepsy. Trauma to the head can cause violent, intractable convulsions.
An anxious family came into my office one day carrying a young female mixed dog. Diagnosis didn't require any expertise. The patient was stiff and unconscious. An automobile had struck the dog in the head and fractured the frontal bones of the skull. The skin over the fracture was torn and a portion of the brain could be seen under the wound. The owners received a very dismal prognosis but gave permission to see what could be done.
The surgery went well. Under anesthesia, fragments of bone were removed along with injured bits of brain tissue. A net of stainless steel wire woven over the exposed brain gave some protection. Muscle tissue sutured to the wire provided an additional safeguard against future injury. Sutured skin covered the repair job.
The dog regained consciousness the following day and was apparently normal. The wound healed without problems but a month after discharge the family returned the patient and requested euthanasia.
The bitch had suffered a complete change in personality. A sweet affectionate pet had turned into a mean sullen animal that couldn't be trusted around the children. Neurosurgeons tell us that this is a common aftermath of brain damage. Scars form in nerve tissue weeks or months after injury and can cause a marked change in behavior.
The above description of some of the more common causes of convulsions in animals concludes part one of "Seizures and Epilepsy." A brief description of cellular structure and function of the nervous system, also included, was intended to program our brain cells in preparation for Part II. Our neurons should now be tuned to accept a discussion of hereditary epilepsy which will include breed susceptibility, methods of diagnosis, treatment and management. This article is scheduled for a later issue of Dog News.
"Epilepsy. You're never going to eliminate it," stated veterinary researcher/teacher, Dr. Roger M. Clemmons, with what sounded like absolute certainty.
Hopelessness is not Clemmons' message, though. He makes a strong case for pragmatic, positive action in Scottish Terrier, and all canine, breeding programs.
Associate professor of neurology at University of Florida's College of Veterinary Medicine, Dr. Clemmons is familiar to STCA members as one of the veterinarians who, in the 1970s, did the original research on Scottie Cramp at Washington State University.
"I still feel a lot for Scotties because of my work with Ken Meyers on Cramp," said Clemmons. There may not be a Scottie in Clemmons' backyard, but this self-acknowledged terrier man shares his Gainesville, Florida home with a Jack Russell Terrier, whose exploits against squirrels delight him.
Unlike Scottie Cramp, the inheritance of epilepsy is very complex," compared Clemmons. "It involves at lease six gene pairs, and it takes three matches out of those six pairs", to produce epilepsy. This fact was news to me, as it may be to you. It's been acknowledged by veterinary researchers for about 10 years.
The paradox is that two normal parents might each carry only two matches of these six pertinent genes and, thus, not be epileptic themselves. However, the roulette wheel of breeding may spin matchups of three or more of those critical genes to one or more of their offspring. Result: epilepsy.
In plain language, said Clemmons: "You can breed two normal dogs and get all epileptics. Or you can breed two epileptics and get all normal dogs."
"A disease like Scottie Cramp, you can eliminate," pointed out Clemmons. "Cramp is a simple, one gene defect with recessive inheritance."
Clemmons was not judgmental about our breed's failure to work out Cramp. Comparing the two disorders, he stated simply, "We can't even get rid of Scottie Cramp."
However, epilepsy is a different story. Clemmons is realistic about its complexity.
"Epilepsy, we're going to have to live with. The problem with the term 'epilepsy' is that too many breeders look at it as only an inherited disorder."
British geneticist, Malcolm Willis, agrees. In his popular Genetics of the Dog (1989), Dr. Willis cautions that it is, "dangerous for breeders to immediately assume that they have a genetic problem on their hands. Only when other possible causes have been checked as far as possible and been eliminated should the breeder begin to consider idiopathic epilepsy." That is not a light statement for a geneticist and German Shepherd breeder, who also wrote the definitive book on the Shepherd breed. German Shepherds are affected by a high incidence of inherited epilepsy and Willis had done much of the pedigree documentation of the disorder.
Here's where definitions and diagnostics become important.
First, the term "idiopathic." Idiopathic means, "of unknown causes." Idiopathic epilepsy is what classically is defined as true epilepsy or inherited epilepsy. It's the diagnosis breeders would rather not hear.
The best description of epilepsy I've found comes from the 1991 textbook by Clemmons' colleague in neurology at the University of Florida, Dr. Cheryl Chrisman. Anyone looking for a comprehensive, easy-to-understand overview of true epilepsy and acquired seizure disorders should read Chapter 8, Seizures," pp.177-205, in Dr. Chrisman's Problems in Small Animal Neurology.
"Epilepsy can be defined as a disorder characterized by recurrent seizures with no active underlying disease process occurring in the brain. Epilepsy may be caused by an inherited bio-chemical defect or may be acquired because of some cerebral insult resulting in a focus of neurons with altered thresholds."
Speaking of threshold, "Every animal, including the human, has a so-called seizure threshold that is genetically determined," writes Dr. Alexander de Lahunta in the 1986 STCA Handbook. "When this is exceeded, an uncontrolled neuronal discharge occurs that may cause what we observe as a seizure. This threshold varies among individuals and presumably is exceptionally low in those with idiopathic epilepsy. Genetic factors are believed to determine the structural and metabolic basis of this threshold. The role of the environment in influencing this threshold is unknown."
What to do
What should the owner do is his dog seizures? "The first step, which may be the most difficult for the concerned owner is to leave the dog alone!" directs Dr. de Lahunta. "This dog will usually not injure itself except for occasionally biting its lips or tongue. The dog will not 'swallow its tongue'."
Many have never seen a seizure. A typical epileptic seizure might progress as Dr. Samuel Hodesson once described in Dog News:
"Observant owners will notice a change in behavior for a brief period during which their pet may become restless, look worried, seek attention or stare into space. Loss of consciousness follows and pupils of the eyes dilate."
"Excessive salivation and chewing movements, commonly called chewing fits, may follow. Legs stiffen and the dog falls on its side. Paddling or running movements may alternate with periods of rigid extension of the legs and arching of the back. The patient may urinate or defecate during or after the seizure."
"Most attacks last but a minute or two and the recovery period is usually short though it can persist for as much as a day. During this state the dog may appear confused or wander about and bump into objects in the room."
If your dog has a seizure, where do you start when it's over?
With questions, and lots of them. If your dog has more than one seizure, the recommendation is that a veterinary evaluation should follow. Your veterinarian should ask you (and if he doesn't. be prepared to offer the answers to these questions)-
Questions from "The Diagnostic Approach to Seizures," Veterinary Medicine (July, 1993):
1. What does the pet look like when it is seizuring?
2. What is the duration and frequency of the seizures?
3. Are there any localizing signs?
4. Has the pet ever had an illness resulting in a fever?
5. Has the pet been exposed to toxicants?
6. Has the pet sustained any type of trauma?
7. Is the pet's vaccination status current?
8. Has the pet recently been in a kennel or pound?
9. Has the pet shown any signs of illness?
10. Do any of the pet's littermates have problems?
11. What is the pet fed, and how often is it fed?
12. Does the pet roam?
Clemmons suggests keeping a calendar of seizure activity. He said, "I've known dogs who only seizured when watching Lassie on TV, or in the kitchen before food." Dr. Clemmons assured me that the Lassie example was no joke. He explained that for a dog that seizures at mealtime the stimulus could even be the pattern of the floor under the dish. One gets the idea that seemingly insignificant things may trigger seizures. You should be watching to discover the triggers. For instance, a female in estrus or pregnancy may have more frequent or more severe seizures.
Diagnostic tools your veterinarian may use in addition to your personal history are: physical exam, blood tests (complete blood count and serum chemistry profile), urinalysis and neurological exam. If these initial tests don't give an answer, your veterinarian may recommend a second tier of tests. Such evaluations may include, cerebrospinal fluid analysis, skull and/or thoracic/abdominal radiographs, electroencephalography (EEG), computerized tomography (CT scan), and magnetic resonance imaging (MRI). These tests could require use of a specialized care facility.
Types of Seizures
To get academic, there are three types of seizures; generalized, partial and partial with secondary generalization. It is important to determine which type of seizure a dog has because the type can show: 1) whether the condition is "true" epilepsy (the inherited variety); or 1) whether the condition is the result of an active disease process affecting the brain, or the result of a past insult to the brain which has left localized neurologic damage.
Total, or bilateral involvement of the brain causes "generalized" seizures. They may be mild and cause no loss of consciousness, or they may be severe, causing total loss of consciousness. "Generalized seizures are most often associated with metabolic disturbances, toxicities, nutritional deficiencies, and true or inherited epilepsy," states the Chrisman text.
A partial seizure is one in which the seizure discharge is focal, meaning a localized part of the brain is involved. Partial seizures are not typical of true inherited epilepsy. Underline this in your own brain! Chrisman says: "Partial seizures are most commonly associated with a focus of brain damage caused by an infection, metabolic insult, traumatic insult, or neoplasia."
Partial seizures include many forms of behavior: unilateral muscle twitching of the face or limbs; bizarre, aggressive behavior; chewing, lip smacking, and excessive swallowing; running; confusion; "fly biting;" star gazing;" hallucinations; episodic tail chasing and self-mutilation; and some chronic episodic vomiting and diarrhea.
Then, to complicate matters, there is the partial seizure with secondary generalization. It can look very much like a generalized seizure. The partial phase may last only seconds, and the owner may miss seeing it. However, it is very important, especially for the breeder, to determine if the seizure is partial or partial with secondary generalization. Both are usually associated with non-inherited focal lesions of the brain rather than true epilepsy.
Helpful clues to identifying the seizures as partial or partial with generalization are asymmetric motor activities. If you can detect asymmetric movements, maybe as simple as turning the head and lifting a forelimb before collapse, severe contracting of one side of the face, a difference of tone or movement in the limbs on one side, or any of the previously listed partial seizures, the condition with which you are dealing probably is not true epilepsy, according to the Chrisman test. Compulsive circling to one side during recovery also might indicate focal, rather than general brain involvement.
Chrisman's book differentiates between seizure types;
"An acute onset of severe, frequent seizures could indicate an infectious, toxic, nutritional, metabolic or neoplastic process."
"An intermittent seizure disorder with no other neurologic abnormalities in between the seizures, which has been going on for a year or more, is most likely epilepsy."
Causes of Seizures
Rather than go into great detail about all the problems which can cause seizures, I point you to Dr. Chrisman's Differential Diagnosis table, (Problems in Small Animal Neurology, p. 83). It summarizes conditions common at different ages:
"Young (under 9 months of age)-- congenital hydrocephalus; lissencephaly; lysosomal storage disorders; distemper...and other causes of encephalitis; trauma; toxicity--lead, organophosphates, etc.; hypoglycemia; hepatic encephalopathy--portacaval shunt; other congenital defects with associated metabolic disorders; thiamine deficiency."
"Adult (9 months to 5 years)--distemper...and other causes of encephalitis; trauma; toxicity--organophosphates, etc.; hypoglycemia; hepatic encephalopathy--portacaval shunt, acquired cirrhosis; other acquired metabolic disorders; true epilepsy; acquired epilepsy; cerebral neoplasia--rare."
"Old (5 years and older)--distemper... and other causes of encephalitis; trauma; toxicity--organophosphates, etc.; hypoglycemia-insulinoma; hepatic encephalopathy--acquired cirrhosis; other acquired metabolic disorders; acquired epilepsy; cerebral neoplasia."
One point which might be made here is that hypoglycemia is the most common metabolic cause of seizures in small animals. The causes of hypoglycemia are myriad: severe infestations of parasites, stress, excessive insulin during treatment of diabetes mellitus, insulinomas (pancreatic tumors secreting excessive insulin), hypoadrenocorticism (Addisons's Disease), hypopituitarism, chronic liver disease, acute pancreatitis, and sepsis.
Dr. Clemmons did state, however, that metabolic sources are not the most common cause of seizures. "If you look at all mechanisms behind seizures, infectious/inflammatory brain diseases are probably the most common cause of seizures," said Clemmons. He placed trauma and post trauma as the second most common cause of seizures. Metabolic problems, toxicity, and neoplasia (cancer) probably stand in third, fourth and fifth places, according to Dr. clemmons. He does remind that a cause like cancer can move up in that order within specific breeds that have a higher incidence of cancer, or in old dogs that also are at greater risk for cancer.
"Probably 40% of seizures are idiopathic," said Clemmons. "That doesn't mean that they all are inherited, but that we can't say they aren't. The majority of seizures we see are acquired ones." He noted again that infection/inflammation, either current or past, are prime causes.
Numerous other conditions can cause seizures. Just one of these of special interest to Scottish Terrier breeders is the fact that hypothyroidism can be a precipitant of seizures. VWD researcher, Dr. Jean Dodds, has identified Scottish Terriers as a breed with a high incidence of hypothyroidism as well as von Willebrand's Disease.
Most frequent toxic causes of seizures are lead and organophosphate poisoning. Actually, said Dr. Clemmons, lead is a fairly rare cause of seizures these days because of decreased sources of lead contamination. Still, lead toxicity might be considered if a dog lives in an older home where lead-based paints were used. Dr. Chrisman's chart of chemicals that cause convulsions lists 128 substances, just a few of which are ethylene glycol (antifreeze), theobromines (chocolate), castor beans, narcissus bulbs, nicotine and gasoline.
Especially worrisome to breeders is the fact that idiopathic epilepsy can be the "easy" diagnosis if an incomplete work-up is done, or if the key "clue" has been missed. "Did we just not find the cause?" is the question many dog owners end up asking themselves, hoping that's the answer instead of idiopathic epilepsy.
High Incidence Breeds
Inherited epilepsy does have a higher incidence in some breeds. It has been studied in Beagles, German Shepherds, Keeshonds, Tervuren Shepherds and Irish Setters. Miniature Poodles, Golden Retrievers, Siberian Huskies, Wire Fox Terriers, Cocker Spaniels and Saint Bernards also are suspected of having inherited epilepsy (Chrisman text). Veterinary Medicine's July, 1993, issue adds Alaskan Malamutes, Collies, Dachshunds, Labrador Retrievers, Lhasa Apsos, Mastiffs, Miniature Schnauzers, Standard Poodles and English and Welsh Springer Spaniels as breeds with a high incidence of primary epilepsy. Boxers and Shetland Sheepdogs also are listed among affected breeds in Willis' Genetics of the Dog.
In addition to the above breeds, Veterinary Medicine (July, 1993) records breed dispositions to seizures caused by inherited or congenital disorders which include many of the above breeds as well as Chihuahuas, Boston Terriers, Maltese, Yorkshire Terriers, Chow Chows, Pomeranians, Toy Poodles, Shih Tzu, Irish Wolfhounds, Border Collies, Basset Hounds, English Setters and German Short-haired Pointers. Still no Scotties listed.
Interestingly, male dogs are affected with true inherited epilepsy to a greater degree than females. The Merck Veterinary Manual's 1986 edition quotes the incidence of epilepsy in Beagles as 11.9% in males and 2.6% in females, and suggests involvement of a sex-linked suppressor gene. Other studies corroborate these figures. Willis' book mentions a 1975 Keeshond study which showed seizures about 4 times as prevalent in males as in females; a 4.6 to 1 male-to-female ratio among Beagles with clinical symptoms of epilepsy in a 1971 study; and a 3.6 to 1 ratio weighted toward males in a 1974 British study of German Shepherds.
General frequency of epilepsy? Chrisman's text states:
"Acquired Epilepsy: Incidence, Frequent."
"True Epilepsy: Incidence, Frequent in Certain Breeds."
Scottish Terriers are listed by neither Chrisman, nor in any of the other literature I examined, as one of the breeds with a high frequency of epilepsy!
Dr. Clemmons seconds that; "Seizures aren't a big problem in Scotties. My gut reaction about Scotties is that incidence is probably 1% or less, certainly not like in other breeds where epilepsy is commonly documented." However, Clemmons adds that there is no breed of dog or even non-purebred group of dogs that is free of seizures.
The overall incidence of epilepsy in dogs is, in fact. about 1%, according to Clemmons. He put the incidence in Beagles at 5.9%, one reason being Beagles' former use in highly inbred laboratory colonies.
Control of Seizures
For those who do have dogs with epilepsy, control is the interest.
Relatively normal lives are possible for most seizure-affected dogs, if medicated with appropriate anticonvulsants. Stephen Ettinger's Textbook of Veterinary Internal Medicine (1989) quotes one study which shows seizure control achieved in about 60% of affected dogs when phenobarbital is used. Ettinger defines seizure control as a 50% decrease in seizure frequency without drug intoxication.
Phenobarbital is the drug of choice for seizures. "Always use it first," asserted Clemmons. Ettinger goes so far as to claim, "Phenobarbital is the only anticonvulsant with proven efficacy in controlling seizures in dogs."
Primidone (Mylepsin or Mysoline) and diphenylhydantoin (Dilantin) are also drugs mentioned in seizure control. There are other less commonly used pharmaceuticals which may be tried in hard-to-control cases. Clemmons rarely uses primidone because of its potential for liver toxicity. Also, though diphenylhydantoin still is listed among veterinary anticonvulsants, Clemmons said it is probably an ineffective drug in dogs, even in combination with other medications.
Liver toxicity is, in fact, the most common problem of long-term anticonvulsant medication. With Scottish Terriers at greater risk of liver problems than many breeds, this fact can make control of seizures in some Scotties a challenge. Clemmons tempered that by saying, "Toxicity from anticonvulsants is somewhat independent of usual causes of liver disease. Even if a dog has liver disease, it still may do well on anticonvulsants, with modified dosages."
Unfortunately, "all long-term anticonvulsant therapy has some negative effect on liver function, but phenobarbital may have the least effect" Chrisman text). Serum drug levels should be monitored at least every six months after steady state and seizure control have been achieved," directs Ettinger.
Fortunately, treatment with phenobarbital is not expensive. Chrisman lists a 1990 sample cost of phenobarbital therapy for a 14 kg (30 pounds) as 14 cents a day for a starting dose.
When should drug therapy be stated?
Ettinger suggests: "As a rule, anticonvulsants should be considered when single seizures are occurring more than once every six weeks or clusters of seizures are occurring more than once every eight weeks." This is not a hard and fast rule, according to Clemmons: "Single severe seizures of clusters must be treated. You have to look at the severity."
A different angle is given in Veterinary Medicine's "Symposium on Seizure Disorders" (July, 1993): "There is convincing experimental evidence that repetitive seizures may irreversibly lower the seizure threshold in some patients, a phenomenon referred to as kindling...Therefore, early aggressive anticonvulsant therapy might result in better long-term seizure control." However, amplified Clemmons, it is important to get enough frequency of seizures to know if medication is effecting a change. When medication is started, said Clemmons, "I don't like to play catchup." He suggests beginning with high dosages and working down to minimum levels which will control seizuring.
New Drug Therapy
An interesting new therapy which Clemmons pointed out is use of potassium bromide in conjunction with phenobarbital. This treatment is not described in all vet texts. I checked Ettinger's, the Bible of many veterinarians. Potassium bromide therapy is not mentioned in its chapter, "Seizures". Your own veterinarian may be unaware of the advantages of potassium bromide. Chrisman's text discusses it extensively.
Phenobarbital/potassium bromide is a combination especially helpful in dogs with severe cluster seizures not controlled well with phenobarbital alone, according to Clemmons. He also indicates its value in dogs having liver problems which preclude receiving the necessary control levels of phenobarbital. "With potassium bromide, you can usually reduce phenobarbital to 1/8 the normal dose," said Clemmons.
One investigator Veterinary Medicine quotes (July 1993) even estimates that 50% of epileptic dogs can be managed with bromide alone. The same report declares that bromide is the most satisfactory secondary anticonvulsant. It estimates that about half the dogs that continue to have seizures on what should be adequate phenobarbital dosages will benefit from addition of bromide.
Potassium bromide has been in use with human epileptics since 1857. For dogs, its use is more recent. The special value of potassium bromide lies in the fact that it does not induce production of liver enzymes and does not interact with drugs which the liver metabolizes (e.g. phenobarbital). Veterinary Medicine calls bromide the anticonvulsant of choice for dogs with liver disease (July, 1993).
The down side of potassium bromide therapy is that it may not be easily available to your dog. This chemical is not approved for use in dogs, and an investigational drug license is needed to legally dispense it. There can be human toxicity with excessive handling of the raw chemical. Not commercially available, potassium bromide must be purchased from chemical supply houses as an American Chemical Society chemical grade reagent (addresses of five chemical supply houses which carry it listed in Chrisman text). To try potassium bromide therapy, you may need to work with your nearest veterinary medicine teaching facility. However, it would be worth checking to see if your own veterinarian might obtain the investigational drug license necessary to dispense potassium bromide.*
The simplest course of action, according to Clemmons, is for a local veterinarian to locate a pharmacy within his state which has the investigational license to formulate and compound chemicals like potassium bromide. The veterinarian then can prescribe potassium bromide from that particular pharmacy, even though he himself doesn't have an investigational license. Dispensing can be done by mail-order if necessary. Chrisman's text lists the following information about potassium bromide therapy:
Suggested dosage is 25 mg/kg (effective serum level, 500 - 1,000 microgram/ml.). If used with phenobarbital, give orally once daily. If used along, give twice daily. Sedation is noted as a side effect (no other side effects listed). Cost (1990) for 14 kg dog (30 pounds): $.07/day.
Dr. Clemmons commented that potassium bromide can be dosed at a higher level, but that Chrisman's suggested dosage is the usual starting level. He emphasized that if a dog is already on anticonvulsant when potassium bromide therapy is started, the anticonvulsant should be cut by half after the second dose of potassium bromide to avoid excessive sedation. Clemmons said that quantitative blood levels should be done after the first month on potassium bromide and then every six months for dosage adjustment.
*(To apply for an investigational license, contact Marcia K. Larkins, DVM, Chief of Companion and Wildlife Drugs Branch, HFV-112, Center for Veterinary Medicine, Food and Drug Administration, Rockville, MD 20857.)
Other Ideas for Control
Besides medication, special recommendations Clemmons makes for dogs with seizures are:
1. Balance maintenance diet, low in protein.
2. Heartworm preventative - Use diethylcarbamazine (DEC) products (like Filarbits®) rather than once-a-month preventative.
Clemmons suggests avoidance of Filarbits Plus®. Chrisman text says Ivermectin should not be used.
3. Avoid organophosphates for flea/tick control. Instead, use pyrethrin products, carbamates or products with Precor® insect growth inhibitor. He mentions Vet-Kem's Ovitrol Plus® as a good pyrethrin/Precor® product.
4. Avoid drugs known to interact to lower seizure thresholds. A number of drugs can either increase or decrease anticonvulsant concentration. (Chrisman's text lists drugs to avoid if a dog is on anticonvulsant therapy: digitoxin, dipyrone, griseofulvin, phenylbutazone, chloramphenicol, amphetamine and phenothiazine tranquilizers. A common tranquilizer which should be avoided is acepromizine.)
Read, Read, Read
What I've touched on in this article is only the skimmings off the top of the subject of epilepsy. When asked to write, I had only superficial information on epilepsy. I've learned more than I bargained for. My printed sources are listed at the end of the article. They have been forwarded to Gail Gains, STCA Health Committee Chairman, for the Club's reference library. Many of these articles, like Chrisman's text, have extensive bibliographies of their own, from which interested members may dig even deeper. Members desiring to share additional information about epilepsy may contact me (Carole Owen, 9 Coachman's Circle, Big Spring, TX 79720; phone 915/263-3404). If interest warrants, I will be happy to put together a follow-up piece.
To tell you how much I've learned myself about epilepsy, I have to share a personal anecdote. "I've never seen a seizure," I blithely told the first couple of STCA members I interviewed. Well, a few articles of reading later, I discovered that I've probably been living with a seizure disorder for nine years and didn't know it.
The first dog on which we finished a championship has had a bizarre form of recurrent behavior which has never worried me. I haven't even mentioned it to a vet. It seems that minor. Every few months, for many 15 or 30 seconds, Cubby chases her tail or hind leg in a tight circle in one direction, like she's trying to bite a flea off her rear end. However, there are no fleas!
This is an asymmetric motor activity described earlier as one type of partial seizure. Since partial seizures usually are acquired disorders and are not primary epilepsy, I looked for a possible explanation. I remember her breeder telling me Cubby was the only puppy in her litter to survive a raging staph infection. Perhaps the early infection and fever carries the answer?
I am sure many STCA members have learned about seizures on their own, too. An important part of any discussion of seizure disorders in the Scottish Terrier must be input from our breeders.
"You're walking in a minefield. This is an explosive subject," I was warned when I started asking breeders for feedback on epilepsy.
In an attempt to handle the subject with great delicacy, I assured breeders of confidentiality. They shall be identified here only as "Breeder A", "Breeder B", etc., and will be referred to by the generic "he" - even the "she's". Nor will I "point a finger" at any individual dog or line suspected of producing seizures.
Secrecy, A Problem
Breeder A: "Most breeders don't talk about epilepsy. I don't know that we have a true picture. Epilepsy and Scottie Cramp are the two things people don't talk about. People only tell you what they want to. They don't tell you the rest."
Breeder A related a personal experience with a young bitch that started seizuring several points away from her championship: "I was devastated. I'd never had any of that before."
Tests at a well-known veterinary center did not identify a cause for the seizures.
"The veterinarian said, 'You don't have any of that behind you. You can breed her.' I knew better. I didn't."
The bitch was spayed and placed as a pet. When her new owner eventually stopped medication, the bitch had no more seizures. "I often wondered if this was a hormonal situation," pondered Breeder A. "There was no problem with seizures after spaying. If she was a true epileptic, she should have seizured the rest of her life."
Breeder A emphasized his belief that split shot/killed vaccine immunizations can be important in avoiding some seizures.
Early Onset Seizures
Breeder B told of severe, early onset seizures. A pet he had sold seizured at 7 1/2 months of age. Its seizures came in severe clusters of five or six seizures in one day. Several days later, the seizures would repeat. At final count, the puppy had almost 40 grand mal seizures in a month. Chasing another dog a few weeks after seizure started, this puppy broke its leg. The veterinarian predicted the leg would not stay set during future seizures. He put the puppy down.
Because of age at onset and severity of seizures, this puppy likely was not a case of idiopathic, inherited epilepsy, according to its veterinarian. Breeder B emphasizes that a diagnosis was lacking, however. There was no autopsy, nor any final determination of cause. Breeder B had no previous seizures in his own dogs, but set about checking dogs and families of dogs behind his for possible existence of seizure disorders.
A Tragic Dog Fight
Breeder C describes his own tragedy with seizures, the loss of a beloved homebred champion. Seizures started about 1 1/2 months after a monumental attack on this Scottie stud by a male of one of the large terrier breeds. Breeder C calls the fight "horrible" with both dogs covered in blood/mud/saliva. The Scottie suffered a deep gash below his ear and bad punctures on top of his skull.
This Scot died about two months after its first seizure. Breeder C described one of the dog's final seizures as a terrible hour-and-15-minute affair. After that seizure, the dog showed no comprehension of the breeder and exhibited bizarre behavior, "He started 'tasting' - tasting carpet, tasting me, my clothes, the bedspread. When he got to the bottom of his dish of food, he just kept licking. He was mentally gone. Soon he lost bowel and bladder control and went in circles."
Breeder C does not worry about these seizures being hereditary. Veterinary diagnosis: seizures caused by trauma to the head suffered during the dog fight.
Breeder D has groomed many pet Scotties. He told of several with seizure problems, which, if dewormed, would cease having seizures - until they contracted tapeworms again.
"Maybe the breed doesn't have a problem with true epilepsy." speculated Breeder D. "Maybe many seizures are the result of reactions to other primary problems - like allergies or immune problems."
Breeder E: "There are many, many forms of epilepsy. All of us love our dogs. If you've been breeding for a long time and it doesn't show up until late in a dog that you've used extensively, what do you do?" He left his comments as a question.
Breeder F: "We lucked out...had only one epileptic, from a complete outcross. I'll never forget it. I walked out with a bucket of food, and she keeled right over. She was about 9 months old. We did all kinds of blood work. She started seizuring routinely under stress. (An old terrier man) looked at her and said it was definitely epilepsy. We tried various medications. Nothing would work. She would be fine. Then, with a loud noise, she'd go down. We had her spayed. Finally, she was down more than up." The bitch was euthanized at three years old.
Was hypoxia the cause of this bitch's seizures? Breeder F later remembered that, at birth, one bitch in that litter couldn't get going right away and was probably oxygen-deprived. None of the litter mates developed seizures.
Breeder G: "One of our main dogs had seizures forever, and we eventually lost him. The dog was used at stud early in life before we knew he had these problems. He was a very proud dog. It was terrible."
Seizures started as 2-minute episodes when this dog was two years old. "First, it was once every 6 months, then every month, then every two weeks, and by 8 years old, every day." Breeder G described the terror of the 4-hour seizure. Ice packs were kept in the freezer for packing this dog during long seizures.
The dog finally died of liver failure. "Phenobarbital does the liver in," said Breeder G, "and Scotties’ livers are iffy."
Breeder G mentioned that the dog had received combination shots as a puppy: "I had a feeling that in pups given combo shots, bang-bang-bang, something happens. I now stretch out shots forever, and give killed parvo and killed vaccines whenever possible."
After living with seizures, Breeder G feeds what he terms "environmentally correct food" and never uses flea/tick sprays or dips. He did suggest that seizures may be familial in nature.
"Epilepsy is no fun," asserted Breeder G. "I wouldn't wish it on anybody, but I guess it's all around us. At a Scottie party, I heard new owners (pet people) talking about their dogs having epilepsy."
Breeder H thinks Scottish Terrier breeders should worry about acquired seizures, too.
He said, "If our breed has certain tendencies toward conditions which can produce seizures, we need to take the seizures as a point-blank warning to breed away from those conditions. Sure, a breeder may truthfully claim he hasn't had idiopathic, inherited epilepsy. But perhaps his dogs have had seizures that are inherited second-hand, as step-children of other problems to which the Scottie is predisposed. We need to accept seizures as a red flag to deal with dirty laundry."
A Wake-Up Call
Breeder I: "The problem with epilepsy is it's hard to distinguish idiopathic, inherited epilepsy from seizures brought on by a specific cause. Unfortunately, people always want to give themselves the benefit of the doubt. When a breeder has a dog with seizures, he is inclined to blame anything but inheritance. Because of the seriousness of the problem, he should assume the worst."
"A time bomb," Breeder I calls the problem of seizures in Scottish Terriers. "I have a file of pedigrees of dogs that have seizures." Flipping through the file, Breeder I said, he sees definite tendencies.
Distilling Breeder I's evaluation of those files into one simple sentence of my own wording: "If a popular stud dog produces a condition like seizures, the problem eventually will compound itself."
"There is no doubt that some forms of epilepsy are inherited," said Breeder I. He, himself, has had a few dogs with seizures. Unlike many other breeders with whom I talked, he not once tried to assign the blame of those seizures to any acquired cause.
"We feel like we have to be ruthless," Breeder I said of elimination of any problem dog from a breeding program. "It's easier for breeders who haven't painted themselves into a corner," he continued about the values of diversity versus extremely tight breeding.
"One idea that would help is an open health registry. People who don't have the problem (yet) would cooperate. Once you do it (share information), you find out it's not that hard."
"It's definitely time for a wake-up call for our breed," warned Breeder I. "Epilepsy is not something we can live with. You can't deal with seizures in pet puppies. A dog with seizures: you're selling a major heartache and a major headache. If Scottish Terriers get a reputation for epilepsy, our pet puppies will be hard to sell."
Diversity, But Accord
There is certainly no lack of diversity in type and cause of seizures in Scottish Terriers, nor in our breeders' opinions as to whether the seizure disorders in their own dogs are inherited. I wish space permitted even more breeder interviews.
What no one claims is that seizure disorders can be taken lightly. There is unanimous accord there! From that consensus, perhaps Scottish Terrier breeders can move forward to work together. I discovered in my interviews that there is already a certain degree of openness about the subject of seizure disorders. Why not take the first step and discuss seizures yourself with other breeders? Especially if you are willing to share your own experiences, you will often find someone willing to share right back.
What might you get if you were to breed two dogs that have idiopathic epilepsy? Clemmons stated earlier: Maybe 100% normal dogs.
However, an interesting case study in Veterinary Medicine (November, 1991) reports a litter produced by the accidental mating of two related Labrador Retrievers which each had idiopathic epilepsy. The puppies started having seizures at an unusually early age. Dr. Valrie Gerard and Dr. Cliff Conarck explained that the onset of seizures in dogs with idiopathic epilepsy usually occurs between one and three years of age, but rarely before six months of age.
In this particular litter, three puppies of the 10 started seizuring between 54 and 63 days of age. Two others began seizuring at 18 and 20 months old. With two puppies having died of unrelated causes by the time the study was written, five of eight surviving litter mates (63%) were affected by seizures. The authors report similarly high percentages of epileptic offspring (30% to 100%) in other litters from two epileptic parents. Of particular interest was the authors' recommendation: "The occurrence of seizures in unusually young puppies warrants checking the family tree for the presence of idiopathic epilepsy."
Clemmons pointed out that the Gerard/Conarck study and recommendations are based on a small amount of data. He reiterated that in young dogs infection, metabolic disease and trauma are the primary causes of seizures; and that true inherited epilepsy usually doesn't appear until puberty or perhaps two years of age or later.
Another article tracing the incidence of epilepsy through four generations of test-bred epileptic dogs is, "Inheritance and Idiopathic Canine Epilepsy", by Dr. James Cunningham and Dr. George Farnback (Journal of the American Animal Hospital Association, July/August, 1988).
Cunningham's and Farnback's conclusions: "Genetic mechanisms play an important role in transmission of some and possibly most cases of idiopathic canine epilepsy, although the mechanism for this inheritance is not yet known. Until the genetic mechanisms involved are more clearly delineated, the authors recommend that veterinarians advise owners of dogs with idiopathic epilepsy that:
1) the idiopathic form of canine epilepsy may have a major genetic component;
2) it generally is impossible without considerably more test breedings to determine the degree of involvement of either dam or sire in producing epileptic offspring;
3) it is unwise to breed an epileptic dog or repeat the breeding that produced it and it is unwise also to breed its litter mates."
Norwich Terriers are a breed, like our own Scottish Terriers, which has not been mentioned yet in any of the veterinary literature I examined as having a high incidence of epilepsy. Norwich breeders are getting concerned, though. Wrote breeder Knowlton Reynders in "Epilepsy in Norwich" (Dog News, January, 1992):
"I feel very strongly that we have it, visibly and less visibly, in many lines of our breeding - old and new. In fact, no one can say with certainty that one is entirely clear of the problem. The evidence strongly suggests that idiopathic seizures are transferred genetically. And the solution is diligently to breed away from any animal with a history or lineage containing suspicious seizures."
Make Intelligent Choices
"The problem with epilepsy: this is not simple Mendelian genetics. You cannot breed it out," repeated Dr. Clemmons. "All you can do is make intelligent choices. If you breed two dogs and you get seizures, don't do it again."
"Maybe, looking back, you might discover that when you get epilepsy is with long-nosed Scotties," hypothesized Clemmons.
Far-fetched idea. I thought to myself. However, what did I run across in research? The chart, "Differential Diagnosis of Seizures in Dogs and Cats," in Veterinary Medicine (July, 1993) lists seizures due to primary brain tumors (meningiomas) as predispositions of dolichocephalic dog breeds.
What is that "d" word? I checked the dictionary: "Dolichocephalic: long-headed; having a breadth of head small in proportion to the length from front to back." Isn't that the Scottish Terrier? True, seizures due to primary brain tumors like meningiomas would certainly be an acquired seizure disorder. However, who can say what future research will turn up as far as special breed characteristics that might come associated with primary epilepsy? It might not be long noses, but Clemmons did point out eventually we could discover that certain visible traits are linked with epilepsy.
A practical problem hindering learning more about epilepsy is research funds. "One time, dogs were a model of human epilepsy," said neurologist Clemmons. "Since they aren't any more, funding is less."
One program active in the study of epilepsy is the American Canine Epilepsy Service. Directed by Dr. Betsy Dayrell-Hart, V.H.U.P., School of Veterinary Medicine, University of Pennsylvania, 3850 Spruce Street, Philadelphia, PA, 19104. The service offers advice on treatment and gathers data on the disease. You may wish to contact the service.
Good Advice: Share Information
"Epilepsy is so complicated," asserted Clemmons still again. "The only thing you can do is pass information that, 'That wasn't a good match'."
Clemmons reminds Scottish Terrier breeders that, until there is gene mapping, we can't say with absolute certainty that a case in inherited. We can only guess. Here's where Clemmons thinks an open registry might help. "If you're a breeder, and you're getting a problem you want to find out where it is. Make reasonable choices and pass information back and forth between breeders. We should be saying things to each other like: 'You're doing a lot better than me. What are you doing better?'"
The perspective Clemmons puts on epilepsy for individual Scottish Terrier breeders is: "If you're getting more epilepsy than Beagles (5.9%), you're not doing as well as the Beagles can do on their own." Clemmons likes the comment he once heard from a knowledgeable person in one of the national hound clubs: "In all honesty, all you can do is make your best guess. If you make a wrong guess, try to make a better guess next time."
A final personal note I might put on the subject: Scottish Terriers are not yet in the textbook lists of those breeds highly affected by seizure disorders. Will it stay that way?
Currently, Scottie Cramp and sensory neuronopathy are the only two disorders listed under the Scottish Terrier breed in Chrisman's comprehensive neurology textbook. I'm betting a veterinary text from 40 to 50 years ago would not have listed Scottie Cramp. We did not deal with that disorder. We are in the textbooks now. Will we deal with seizure disorders.
October, 1993 - Roger M. Clemmons, D.V.M., PhD, Associate Professor of Neurology, Department of Small Animal Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 3261-0126.
1) Problems in Small Animal Neurology, Second Edition, by Cheryl L. Chrisman, D.V.M., M.S., EdS; Chapter 8, Seizures," pp, 177-205; and Table on "Breeds, Age Ranges, and Specific Disorders," pp. 28-31; Lea & Fabiger, Philadelphia, PA 1991.
2) Textbook of Veterinary Internal Medicine, Diseases of the Dog and Cat, Volume 1, Third Edition; by Stephen J. Ettinger, D.V.M.; Chapter 15, "Seizures," pp. 66-69; W.B. Saunders Co., Philadelphia, PA, 1989
3) Symposium on Seizure Disorders, Veterinary Medicine, July, 1993.
"Understanding the Fundamentals of Seizures," by Linda G. Shell, D.V.M., pp. 622-628.
"The Differential Diagnosis of Seizures," by Linda G. Shell, D.V.M., pp 629-640.
"The Diagnostic Approach to Seizures," by Linda G. Shell, D.V.M., pp. 641-646.
"Anticonvulsant Therapy: A Practical Guide to Medical Management of Epilepsy in Pets," by Karen R. Dyer, D.V.M., PhD. and Linda G. Shell, D.V.M., pp. 647-652.
"Managing Patients with Status Epilepticus," by Karen R. Dyer, D.V.M., PhD. and Linda G. Shell, D.V.M., pp. 654-659.
4) "Identifying the Cause of an Early Onset of Seizures in Puppies with Epileptic Parents," by Valrie A. Gerard, PhD and Cliff N. Conarck, D.V.M.; Veterinary Medicine, November, 1991, pp 1060-1061.
5) Inheritance and Idiopathic Canine Epilepsy," by James G. Cunninghan, D.V.M., PhD. and George C. Farnback, V.M.D., PhD.; Journal of the American Animal Hospital Association, July/August, 1988.
6) Genetics of the Dog, by Malcolm B. Willis, BSc., Phd.; Chapter 9, "Genetic Diseases of the Brain and Central Nervous System," pp.180-187; Howell Book House, New York, NY, 1989.
7) "Canine Epilepsy - Seizures," by Alexander de Lahunta, D.V.M., PhD; 1986 Scottish Terrier Club of America Handbook, pp. 127-131.
8) "Epilepsy in Norwich," by Knowlton A. Reynders, Dog News, pp. 90, 188, 190, January, 1992.
9) "Epilepsy and Seizures in Dogs - Are They the Same?" by Samuel Hodesson, D.V.M., MPH; Dog News, Nov. 1, 1991 and Dec. 6, 1991.
Epilepsy is an electrical disturbance of the brain characterized by a brief upset of mental and body functions referred to as seizures. Nerve cells of the brain normally emit electrical impulses. These electrical impulses flow harmoniously together through the brain and keep the mind and body functioning properly. If brain nerve cells are injured or upset, they may occasionally emit excessive abnormal electrical impulses. When this generalized electrical disturbance occurs, a seizure results.
2. What causes epilepsy?
Anything that can injure or upset the nerve cells of the brain can cause them to emit abnormal electrical impulses and produce a seizure. Since toxicity, encephalitis, low blood sugar, liver problems and brain tumors may also cause seizures, you should see your veterinarian when seizures first appear. Epilepsy can be defined as intermittent seizures with no active brain disease occurring. Epilepsy may develop from mild residual nerve cell injury following head trauma or encephalitis. The first seizures may occur several months to a year after this injury. The delay in onset of the seizures often makes it difficult to determine what originally injured the nerve cells, but since there is no active underlying disease process occurring in the brain, we often refer to this as acquired epilepsy. Acquired epilepsy can not be passed to offspring.
In certain pure breeds of dogs especially Poodles, German Shepherds, Belgian Tervurns Golden Retrievers, Irish Setters and Beagles as well as others, a hereditary type of epilepsy occurs. In this type of epilepsy, the cells do not develop properly and are capable of periodically emitting these abnormal electrical impulses and producing seizures. Hereditary epilepsy has not been reported in cats.
3 . What happens during an epileptic seizure and what types of seizures do animals have?
During a seizure the normal electrical impulses of the brain are disturbed and the animal may lose control of its body and become confused or unconscious for a short period of time. Only rarely does an animal become vicious during this period. Your pet is more likely to be frightened, if it is conscious.
In a generalized seizure, the dog or cat falls upon its side unconscious with its eyes open. The legs may be very stiff, shake, or paddle. The jaws may make chewing motions, be open or closed. Your pet may also salivate, urinate and/or defecate during this type of seizure. The seizure usually lasts only 1-3 minutes, then the recovery period begins. Your pet does not remember the seizure itself and is not in pain. If there are many seizures in a row or a long seizure over 5-minutes, contact a veterinarian immediately.
In a partial seizure, the animal is usually conscious, but may momentarily lose control of one part of his body or may stare off in space at imaginary objects. The appearance of these partial seizures varies depending on the area of the brain involved. The seizures are usually mild, but can then develop into a typical complete generalized seizure. Complex partial seizures also referred to as psychomotor seizures occasionally occur in animals and the dog or cat may be hysterical run around the room, try to climb the wall or have some other strange behavior. Rarely animals are aggressive with psychomotor seizures. Some generalized seizures are preceded by partial seizures
4. What can be done for your pet during a seizure?
Once a generalized seizure has begun, there is usually nothing you can do to stop it without intravenous or rectal drugs. If multiple seizures occur and involve repeated trips to the emergency service see your veterinarian for valium suppositories which can be given rectally to stop seizures. Your pet should be held or otherwise protected from falling off the bed or down the stairs or injuring itself in any way during the seizure. They will not swallow their tongue. The uncontrollable chewing movements of the jaws may accidentally pinch your fingers if you put your hands into their mouth. If an object is placed in your pet's mouth, breathing may be obstructed and suffocation may occur. If your pet consistently bites and injures its tongue during the seizure, an object can be carefully placed between the back teeth on one side, but care must be taken not to obstruct breathing. Pets may be held and gently stroked or put in a padded environment during the seizure, but should not be tied up. In mild generalized or partial seizures, pet owners report they can calm their dog or cat by stroking or holding them and stop or shorten the seizure.
5. What should be done for your pet during the recovery period after a seizure?
After the seizure, your pet often goes through a recovery period. The appearance and length of this period will vary from animal to animal. Some pets want to urinate or defecate, if they did not do so during the seizure. Some are thirsty and hungry and others are exhausted and want to sleep. You pet should be allowed to urinate, defecate, eat, drink and rest; then they usually return to normal.
Some dogs are very hyperactive during the recovery period. They may constantly pace and bump into objects. If the hyperactivity is severe, your pet may require sedation by drugs to keep them from injuring themselves during the recovery period. See your veterinarian to get valium suppositories especially made at the correct dose for your pet to have on hand when recovery from seizures causes hyperactivity. The suppository is inserted through the anus into the rectum. The anus is the first opening just underneath the tail. The recovery period length varies from a few minutes to several hours in different animals and types of seizures.
The seizure and recovery period are frightening for some pet owners. However, your pet will not die in a brief seizure and usually has no memory of it. Multiple seizures close together or long seizures can cause brain damage and emergency assistance should be obtained to stop the seizure. Most pet owners adjust to the possibility of an occasional seizure and can properly care for their pet during and after the seizure.
6. Can epilepsy be cured?
Epilepsy is rarely cured but the seizures in most pets can be controlled with medication. The medication keeps the abnormal electrical impulses of altered nerve cells to a minimum, so that surrounding nerve cells will not be disturbed and the seizure can not occur. If seizures are mild and infrequent like a few times a year, often no treatment is given. Mild seizures may be treated with herbal therapy, acupuncture or homeopathy. If you are interested in these types of therapies seek a consult from a holistic veterinarian trained in these modalities. Acupuncture may be a helpful alone or combined with more traditional drug therapy in pets with more frequent or severe seizures.
When seizures occur once a month or in clusters (multiple seizures in a row over a short time) drug therapy is often prescribed. Every dog or cat reacts differently to the drugs needed to control seizures and dosages have to be regulated for each individual animal. It may take a larger dosage of medication to control seizures in a small dog than in a large dog. You must be patient and work closely with your veterinarian to find the right drug and the right dosage to control your pet's seizures. Usually the seizures can be kept to a minimum and your pet can be normal in between them. Pet owners often find it helpful to keep a calendar and record dosage and time of daily medication and the occurrence of any side effects and seizures. Your veterinarian can review the calendar and different medication regimens can be tried to see what best controls the seizures without sedation or other side effects.
Phenobarbital and potassium bromide (KBr) are the most common drugs used to control seizures in dogs. The dog metabolizes diphenylhydantoin (Dilantin) differently than humans, so the dosage is much higher than in man and it must be given every 6-8 hours. This makes diphenylhydantoin expensive and inconvenient to use. Phenobarbital and KBr are quite inexpensive and usually can be given every 12 hours to control seizures. Primidone can cause severe liver damage in certain dogs so other drugs should be tried first.
Phenobarbital, valium and KBr are the only anticonvulsants that can be safely used in cats at this time. Cats can not metabolize primidone and diphenylhydantoin very well and they get sick from it. Oral valium is not a good maintenance anticonvulsant in dogs, but will stop an ongoing seizure if given intravenously or rectally. The other anticonvulsants used in man may have side effects in animals and be expensive to use.
Your veterinarian will usually begin with a single anticonvulsant and adjust the dose until the seizures are controlled and there are no side effects of sedation. If there are side effects or the seizures are not controlled, a serum phenobarbital level is obtained. In dogs or cats with seizures that are difficult to control, the oral dosage should be increased until the serum levels is 30 micrograms per milliliter. If serum phenobarbital levels occur above that level, then liver damage may occur.
The most common side effects of the phenobarbital and KBr are sedation and rear limb weakness. If the side effects do not pass in 24-48 hours, the dose should be decreased with your veterinarian's guidance. A few dogs may have bizarre behavior or be hyperactive on phenobarbital. This is not a permanent change and will go away as the medication wears off. For these dogs, mephobarbital may be a better drug choice. Increased appetite, thirst and urinations may be a side effect of phenobarbital and KBr. If these signs are severe, the drug should be decreased or changed as the dog may gain excessive weight. KBr takes longer to be effective than Phenobarbital but may have less side effects of sedation. KBr must be given with food as your pet may be nauseated and vomit if it is given on an empty stomach. KBr is toxic to human and so gloves should be worn during administration and all contact avoided. After 4 month KBr serum levels can be evaluated and control is achieved at 2-4 mg/ml. In dogs with cluster seizures (multiple seizures at one time) the dosage may have to be increased until the serum level is 4 mg/ml. If seizures are not controlled with medication, adding acupuncture may control seizures.
7. How long should medication be continued?
Once medication is begun, it usually is given indefinitely and often for life. The dosage may have to be changed periodically to keep the seizures controlled. Drug tolerance to phenobarbital is common and the dosages may have to be increased the longer the animal is on the medication. Seizures may be well controlled for a period of time and then the animal may have multiple seizures, which do not respond to medication as well as before. You should not be discouraged as animals may go through this periodically and with dosage adjustments the seizures can still be controlled again satisfactorily. Many dogs that have cluster seizures respond well to KBr at higher doses. If there are no seizures for a year, the dosage may be decreased by your veterinarian. Epilepsy rarely spontaneously disappears so some level of medication is often needed for life. Medication may be reduced every 6 months if your pet remains seizure free, but see your veterinarian for assistance in reducing the dosage. Never completely withdraw a drug all at once, as this may send your pet into multiple seizures.
8. Is there any special care for my epileptic pet?
The epileptic animal needs medication every day at a regular time, usually every 12 hours, but in some cases every 8 hours. The rest of the care is the same as for any other animal and consists of a good balanced diet, exercise and regular check-ups by a veterinarian. A complete blood count and serum chemistry profile and bile acids examination should be obtained every 6-12 months. The primary aim of seizure control is for the animal to lead a normal healthy happy life and most of them do. For some pets, over-excitement such as grooming or visits from company exacerbates seizures. Your pet may be given a little extra medication prior to the excitement, but ask your veterinarian for the best dosage. Other pets have seizures during sleep and are not affected by excitement. Some pets develop a pattern of seizures and they occur every few weeks like clockwork. Any patterns can be detected by studying a completed calendar. You can work with your veterinarian and can increase drug dosages during high-risk periods and prevent seizures.
If an epileptic animal becomes sick for any reason, expect that the seizures may become more frequent, especially if the animal has vomiting and diarrhea and does not get the needed amount of medication into its system. If the body chemistry changes due to any disease process particularly liver and kidney disease or thyroid problems, the dosage of medication may have to be changed. Once the disease process is corrected, the seizures become controlled again. Some female dogs and cats have more seizures during their heat period. If this is the case, spaying (ovariohysterectomy) of the pet can correct this. If an epileptic animal needs a tranquilizer for travel do not use phenothiazine derivative tranquilizers (acepromazine) as these drugs may precipitate seizures. Often just increasing the anticonvulsant dose (particularly phenobarbital) will calm them for travel. Valium may also be used, but consult a veterinarian about the effects of combining valium with any current medication.
If an epileptic dog has seizures, which are difficult to control, we also recommend using a daily heartworm medication such as filaribits or using once a month interceptor. Some dogs receiving certain flea products may have more seizures so check with your veterinarian.
9. Will epilepsy become worse with age or shorten my pet's life?
Epilepsy rarely becomes worse with age and some pets, which develop seizures at a very
young age, may even improve and go off medication, as they grow older. Simple epilepsy with seizure control does not shorten your pet's life. If the seizures are not able to be controlled with anticonvulsants and acupuncture the animal should be re-evaluated for some serious brain disease or generalized illness in the body. If your pet only has a few seizures a year, this is considered quite well controlled and he or she should have a healthy long life.
THURSDAY, Jan. 6 (HealthDayNews) -- Researchers have discovered a gene that may be responsible for a rare form of epilepsy in dogs.
While numerous genes associated with human epilepsy have already been found, this is the first gene associated with canine epilepsy to be discovered.
"Five to 10 percent of dogs have epilepsy compared to about 1 percent of humans," said one of the study's authors, Dr. Berge Minassian, a neurologist and scientist at the Hospital for Sick Children in Toronto, Canada. "We've found the first dog epilepsy gene and may have explained part of the reason for the high numbers of epilepsy in dogs," he said.
Results of the study appear in the Jan. 7 issue of the journal Science.
Minassian said he was originally studying the human form of this type of epilepsy, known as Lafora disease. Children appear normal until their teenage years when they begin to have very serious seizures. Minassian said the seizures progress and current medications are ineffective against this form of epilepsy. Eventually, Lafora disease kills those affected by it.
An important step in developing effective treatments for human disease is finding an effective animal model of the disease to test potential therapies. One possibility was dogs, because Minassian said he knew they suffered from an almost identical form of epilepsy called autosomal recessive progressive myoclonic epilepsy (PME).
The dogs most commonly affected by this form are purebred dogs, such as basset hounds, miniature and standard poodles, pointers, corgis, beagles and daschunds, according to the study.
People and dogs with this form of epilepsy can have seizures provoked by light. Something as simple as a hand passing over your eyes can cause enough change in lighting to provoke a seizure, said Minassian.
In collaboration with veterinary neurologists in England, researchers at the Hospital for Sick Children compared the genes known to be associated with Lafora to the same genes in affected dogs. They found that one of the canine genes was, in fact, associated with epilepsy.
However, in humans, the genes associated with epilepsy spontaneously mutate, whereas in dogs, the gene repeats itself over and over again until it stops working, and epilepsy results.
Now that the gene has been isolated, Minassian and his colleagues are working on developing a commercially available test to identify the gene so dog breeders can test their dogs to see if they carry the gene. With controlled breeding practices, it could be possible to eliminate this form of canine epilepsy from purebred dogs, said Minassian.
Dennis O'Brien, a professor in the College of Veterinary Medicine at the University of Missouri, said, "This study will go a long way to making dogs lives better. It will give dog breeders the tools necessary to breed better dogs." And, that will improve the lives of pet owners, because having a dog that has seizures can be very stressful since the disease is so unpredictable and seizures often occur at night, said O'Brien.
O'Brien said that while there is no effective treatment for this type of epilepsy in dogs, there are other treatable forms of the disease. "We can control about 70 percent of epilepsy in dogs," he said.
Veterinarians use the same medicines that control epilepsy in humans to control the disorder in dogs, though some of the newer medications are too expensive for most pet owners, said O'Brien.