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A Clinical Approach to Infertility in the Bitch
By Unknown Author
Several unique features of the canine estrous cycle, togerther with dog sperm longevity, allow for dogs' high conception rate after a single mating. Many bitches, however, are seemingly infertile; that is, they fail to conceive or whelp a normal litter. Determining the cause of apparent infertility requires a logical diagnostic plan. Because of the relatively long interval between estrous cycles in the bitch, dog owners are encouraged to seek veterinary consultation after a bitch's first reproductive failure. Failure to do so may lead to a false assessment, misguided treatment, and possible harm to a potential breeding bitch. The approach to infertility in the bitch described here is used in the clinical practices of the authors and is presented as a guide for dog owners and veterinarians to use together.
Estrous Cycle and Vaginal Cytology
A brief review of the canine estrous cycle, including reproductive hormone patterns and vaginal cytology, follows to provide the necessary background for understanding the rationale of the diagnostic approach discussed in this article (Figure 1).
Proestrus is the phase of the estrous cycle when ovarian follicles develop and produce estrogen. The effects of increased serum estrogen concentration in the bitch include enlargement of the vulva, attraction of male dogs, and thickening and hemorrhage of the endometrium in preparation for pregnancy. Uterine hemorrhage is seen outwardly as vaginal discharge and its onset marks the first day of proestrus. Proestrus typically has a nine-day duration, but may range from two to 15 days. The vaginal mucosa also thickens during proestrus, and the additional cell layers protect the vaginal lining during intromission and contribute to changes observed in vaginal cytology.
The predominant cells observed in a vaginal cytologic specimen from a bitch in proestrus include parabasal cells, which are small epithelial cells with round borders and large round nuclei that stain dark blue with Wright's stain. Parabasal cells originate near the germinal cell layer (deepest layer) of the mucosa. As more layers of cells are added to the vaginal mucosa, the cells on the superficial layer become far removed from the underlying blood supply and therefore degenerate. These are superficial cells, which are the largest epithelial cells; they have angular borders and are anucleate or have very small, faint-staining nuclei. Intermediate cells are those that range between the parabasal and superficial cells in regard to origin and appearance.
Early in proestrus, parabasal cells predominate the vaginal cytology. Red blood cells (RBCs) are also seen and they signal that proestrus has begun. As proestrus continues, the relative percentage of parabasal cells decreases, and the percentages of intermediate and superficial cells increase. White blood cells (WBCs) and bacteria may be seen on the smear and are normal findings. Late in proestrus WBCs will no longer be observed, and the number of RBCs may decrease.
Estrus is defined as the period of sexual receptivity. Estrus duration is typically from seven to nine days, but may range from three to 21 days. The bloody vaginal discharge apparent in proestrus usually diminishes and the vulva tends to soften in tone during estrus. When a male dog attempts to mount the estrous bitch, the bitch will "flag" (shift her tail to the side), and stand for copulation. Serum estrogen concentration during estrus rapidly decreases and the progesterone (also produced by the ovaries) concentration increases. Luteinizing hormone (LH) serum concentration increases approximately one to two days after the onset of estrus and this increase initiates ovulation within 24 to 48 hours and the formation of the corpora lutea. Ovulation occurs over a 24-to 96-hour period during which immature ova (primary oocytes) are released. Primary oocytes require an additional 24 to 48 hours to mature (to secondary oocytes) and are then viable for fertilization for an additional 24 hours.
Vaginal cytology during estrus is characterized by a predominance of superficial cells, no WBCs, rare RBCs, and often large amounts of bacteria in the background.
Diestrus is the phase in which the bitch is under the influence of progesterone. The serum concentrations of progesterone (produced by corpora lutea in the ovary) are increased over basal levels for approximately 60 days. Diestrus ends when luteolysis occurs (corpora lutea degenerate) and the serum progesterone concentration falls to basal levels. At this time parturition occurs in the pregnant female or signs of pseudo-pregnancy (i.e., mammary gland enlargement, lactation, nesting) may occur in the nonpregnant bitch. These signs represent a bitch's response to a normal hormonal event (declining progesterone) and should not be interpreted as an abnormality; some bitches respond more intensely to these hormonal changes than do others.
The onset of diestrus is defined behaviorally as the first day of refusal of the male for breeding, and cytologically as the first day of an apparent change from a predominance of the superficial cells of estrus to as little as 20% superficial cells, with a concomitant increase in parabasal cells. WBCs may also become apparent. These cellular changes represent a loss of the superficial vaginal mucosal layers. The onset of both behavioral and cytologic diestrus may not occur on the same day, and it is important to know when each occurred in retrospectively determining the bitch's fertile period as described below.
Anestrus is the phase between the end of diestrus and the onset of the next proestrus. Although anestrus was once thought to be a hormonally quiescent period, it is now known not to be. It is still not fully understood, however, what triggers the onset of the next proestrus period. The normal length of anestrus may range from two to 10 months but is commonly four to five months. The normal interestrous interval ranges from 4.5 months in German Shepherds to 12 months in Basenji, and although the usual interval is seven months in other breeds, individuals within a breed may vary.
The initial evaluation of an apparently infertile bitch includes collecting a general medical history and complete physical examination. The approach to infertility outlined here is designed for treating bitches that have no apparent systemic disease. Also, the current and previous use of any medication, especially corticosteroids for flea-allergic dermatitis, must be known in making an accurate evaluation. Routine laboratory testing (e.g., complete blood count, serum biochemical profile, and urinalysis) may be indicated on the basis of the animal's history and physical examination.
The possibility of Brucella canis infection must be considered in any bitch presented for infertility, and all dogs should be screened for antibody to B. canis on a routine basis before breeding.
It is also prudent to rule out infertility in the male used for breeding before investigating a bitch for apparent infertility. This is commonly done on the basis of the male's history (e.g., Was the dog siring litters at the time the bitch in question was bred?). Semen evaluation may be necessary to determine the viability of sperm if there is no historical evidence of male fertility.
Classification of Infertility Based on Estrous Cycle History
The apparently infertile bitch can be classified on the basis of prior estrous-cycle characteristics as follows: (1) normal estrous cycle length and normal estrous cycle events; (2) failure to cycle; (3) prolonged interestrous intervals (>10 months); (4) shortened interestrous intervals (>4 months); and (5) persistent estrus.
Normal Estrous Cycles
Bitches with normal estrous cycles are the most common group to present for failure to conceive or whelp a litter. The potential differential diagnosis (Table I) can be investigated by answering the following questions.
Differential Diagnosis for Apparent Infertility in a Bitch with a Normal Estrous cycle
Vaginal or vulvar abnormalities
Failure to ovulate
Underlying systemic diseases
Does normal mating occur? If a bitch will not accept the male for breeding, it is important to determine if the bitch is in estrus. Common management practices may dictate that bitches be bred on predetermined days of the cycle such as Days 11 and 13 (the first day of proestrus is considered Day 1.) A bitch may not be in estrus on these days, however, if her proestrus or estrus deviates from the average duration. The use of daily vaginal cytology and observations of the bitch's behavior in the presence of a male dog (a teaser) are the most accurate means for determining the onset of behavioral estrus.
If the bitch appears to be in estrus but refuses breeding, it is possible that vaginal or vulvar anatomical obstruction prevents intromission or causes painful breeding. Careful digital vaginal palpitation and vaginoscopic examination by the veterinarian are indicated. Contrast radiographic procedures may be necessary to outline anatomical abnormalities, including vaginal masses; and surgery may be necessary for resolution of the problem.
Other possible causes of a bitch's refusal to be bred include the use of an inexperienced male, behavioral problems (of the bitch or the male), and mate preferences. The female should be taken to the male's environment so that he can dominate the breeding event. Some bitches that are transported early in estrus, however, may abruptly terminate estrus behavior as a result of stress or tranquilization. In such cases, transportation in advance of an expected proestrus, or the use of transported semen, may be necessary.
Does mating occur during the bitch's fertile period? The bitch may display estrus behavior for longer that the duration of the time in which she is capable of conceiving. The fertile period can be estimated retrospectively from vaginal cytology by counting back five to six days from the onset of cytologic diestrus. Again, a bitch that is routinely bred on predetermined breeding dates may be bred at a time she is not fertile. This problem most commonly occurs in bitches that are bred early in estrus. Because dog sperm is viable in the female genital tract for four to 11 days, however, conception can occur even if the bitch is bred at a nonfertile time. To optimize the possibility of conception in bitches that have failed to conceive in the past, we recommend a management program as follows: (1) The owner should obtain daily swabs for vaginal cytology beginning on Day 1 of proestrus and continuing throughout estrus. (2) To determine accurately the onset of estrus, the bitch should be "teased" with a male dog every one to two days beginning when the vaginal cytology shows signs of late proestrus/early estrus. (3) Once in estrus, the bitch should be bred every two to four days throughout the duration of estrus regardless of the number of matings that occur. (4) The owner should observe the breedings to be able to report whether they were normal (i.e., whether there was a normal "tie"). (5) Pregnancy should be assessed by ultrasonography 16 to 21 days after breeding.
The vaginal cytology obtained by this protocol will allow the veterinarian to (1) determine when the bitch is likely to be in estrus--which should be substantiated by response to the teaser male; and (2) to determine retrospectively on the basis of the first day of diestrus, the likely fertile period of the bitch. If the bitch was bred during this fertile period, is not pregnant, and the male has been shown to be fertile, then the bitch should be further investigated for infertility.
Does the bitch ovulate? A bitch that is determined not to be pregnant by ultrasonography 21 to 28 days after estrus should be evaluated to determine if ovulation occurred. Serum progesterone concentration at that time in the cycle should be in excess of 5ng/ml. Concentrations between 2 and 5 ng/ml may indicate the bitch has ovulated but is unable to maintain a corpus luteum (hypoluteoidism, to be discussed later). If the progesterone concentration is <2 ng/ml, it is likely the bitch did not ovulate and should be observed for the occurrence of a "split heat." Split heat is defined clinically as the situation of a bitch that goes into estrus, does not ovulate, and is again in estrus within two to four weeks; it is most common in pubertal bitches. Often, ovulation will occur after the second estrus. Ovarian cysts can cause ovulation failure and may be detected by ultrasonography. If ovulation failure without apparent cause has been documented, the bitch may be induced to ovulate at the next cycle by injections of human chorionic gonadotropin. Signs of false pregnancy (a response to a decrease in progesterone levels) at the end of diestrus can serve as an indirect and inexpensive indication that ovulation did occur.
Does the bitch have a normal uterus? When it appears that the bitch's ovarian function is normal (i.e., she has normal estrous cycles and ovulates), it must be determined whether the uterus is capable of maintaining pregnancy. Ultrasonography is a noninvasive method that can be used to evaluate the uterus. In the healthy nonpregnant bitch, during any phase of the estrous cycle other than estrus the uterus is sonographically small and free of luminal fluid and is commonly not detected at all. An enlarged or fluid-filled uterus may be an indication of chronic pyometritis or cystic endometrial hyperplasia. Pyometra can be medically managed with prostaglandin therapy. Cystic endometrial hyperplasia is most common in older bitches or in those previously treated with progestational agents, is diagnosed by uterine biopsy obtained at abdominal surgery, and is not reversible.
Vaginal cultures are often obtained in an effort to determine whether a bacterial infection may be the cause of infertility. The theory behind this practice is that bacteria present in the cranial vagina may indicate bacteria in the normally sterile environment. A positive culture from the cranial vagina does not necessarily reflect the presence of bacteria in the uterus. The only way to determine accurately whether there are bacteria within the uterus is by uterine biopsy and culture of uterine tissue. Bacterial cultures of the caudal vagina are commonly positive and are indicative of the normal bacteria that inhabit that area. Overall, vaginal cultures are of little use in the infertility evaluation unless vaginitis is present. Vaginitis is treated by antiseptic douching.
Does the bitch resorb or abort fetuses? A bitch that becomes pregnant and then loses the litter before Day 30 of gestation will most likely resorb the fetuses, whereas if the litter is lost later in gestation, the fetuses will likely be aborted. Potential causes of such a problem include fetal development abnormalities, uterine or systemic disease of the bitch (including B. canis or canine herpesvirus infection), drug administration, and hypoluteoidism. Resorption or abortion may be suspected in the bitch that is diagnosed pregnant by abdominal palpation (at approximately Day 28 of gestation), and does not whelp a litter. To determine accurately that a bitch is pregnant early in gestation, ultrasonography should be performed after Day 16 to 21 of gestation. Routine abdominal radiography can be used to diagnose pregnancy only after fetal bone calcification--after approximately Day 44 of gestation. When a resorption problem is suspected, the bitch should be sequentially monitored by ultrasonography during the next pregnancy and should have a concurrent serum progesterone analysis to determine if hypoluteoidism occurs. If the progesterone concentration falls below 2 ng/ml, the bitch will likely resorb or abort the fetuses, depending on the stage of gestation; therapy in such cases involves supplementation with progesterone until Day 50. Inappropriately treating a bitch that does not require such therapy, however, can lead to abnormal development of the fetuses (e.g., masculinization of the females) and potential problems with parturition.
Failure to Cycle
Potential differential diagnoses for a bitch that apparently fails to cycle (Table II) may be investigated by answering the following questions.
Differential Diagnosis for Apparent Infertility in a Bitch that Fails to Cycle
Disorder of sexual development
Underlying systemic disease
Concurrent drug administration
Primary ovarian failure
Has the bitch ever had an estrous cycle? The age of the bitch that has never displayed signs of an estrous cycle (primary anestrus) must first be determined. A bitch is not routinely evaluated for primary anestrus until she is beyond two to three years of age, although bitches of many breeds (especially of smaller stature) normally experience a first estrus (pubertal estrus) at a younger age. A bitch with primary anestrus should be evaluated for signs of an intersex condition. The female genitalia may appear normal, but the bitch may have abnormal internal reproductive organs and hence will not cycle. Chromosome analysis may be performed with a blood sample.
Bitches may have a silent heat, i.e., they may ovulate but show minimal to no signs of proestrus or estrus. This can be determined by monthly evaluation of serum progesterone concentration to determine whether the bitch recently ovulated. Weekly determination of vaginal cytology may alert the owner to the onset of the next proestrus and estrus even though signs may not be observed. Such bitches may be fertile but require artificial insemination. Future cycles may be associated with normal clinical signs.
Has the bitch had estrous cycles in the past and now fails to cycle? This problem can occur in a bitch that has concurrent systemic disease, such as an endocrine disorder, a generalized infectious process, or hyperadrenocorticism (Cushing's disease). Laboratory tests are necessary to diagnose definitively such disorders, and with proper treatment the bitch may become fertile. Another consideration is that the use of some medications may suppress the hormonal events necessary for ovarian function. Corticosteroids, frequently administered in the treatment of skin allergies, may be the cause of secondary anestrus.
The functional longevity of the ovaries in the bitch is unknown. Although ovarian function generally declines after the bitch is eight to 10 years old, the ovaries may cease to function earlier (premature ovarian failure). Pituitary hormone serum concentrations reflect ovarian function because when the ovaries fail, the pituitary gonadotropins (follicle stimulation hormone [FSH] and LH) continue to be produced and reach high serum concentrations. Currently, few centers in the United States have the facilities for determining FSH and LH concentrations. Premature ovarian failure is not a treatable condition. This diagnostic approach also can be used to determine if a bitch with an unknown past history has been ovariohysterectomized.
Prolonged Interestrous Intervals
Interestrous intervals greater than 10 months are considered prolonged in dogs, with the exception of the Basenji. In aging females (those older than eight years) the interestrous interval may lengthen. If such prolonged cycles are fertile, an investigation into the cause of the long interval is not indicated. Possible differential diagnoses for infertile cycles that have a prolonged interestrous interval (Table III) may be explored by answering the following questions.
Does the bitch have undetected cycles? A bitch that has a prolonged interestrous interval should be evaluated to determine if a silent heat is occurring between observed estrus periods. This may be determined as discussed above. Housing the bitch with another female may induce an earlier cycle.
Does the bitch have an underlying disease process? The bitch should be evaluated for underlying disease that can delay the onset of an estrous cycle. Hypothyroidism, in addition to causing persistent anestrus, can cause a prolonged interestrous interval. Diagnostic testing, including a response of thyroid hormone (T4) concentration to an injection of exogenous thyrotropin (TSH), is indicated. When hypothyroidism is the cause of the prolonged interestrous intervals, other concurrent signs of hypothyroidism, including dermatologic abnormalities, inappetence, and lack of energy, are usually apparent. In bitches with persistet anestrus or prolonged interestrous intervals, an attempt can be made to induce estrus hormonally. At the University of California-Davis, studies are currently under way to evaluate the administration of gonadotropin-releasing hormone (GnRH) to induce estrus and ovulation in bitches. Endogenous GnRH is released from the hypothalamus and causes the pituitary to release FSH and LH. Administering GnRH therefore simulates normal physiologic events of the estrous cycle.
Shortened Interestrous Interval
Cycles that recur every four months or more frequently are considered abnormal. Possible differential diagnoses for this problem (Table III) can be investigated by answering the following questions.
Does the bitch ovulate? Determining the serum progesterone concentration will indicate whether frequent estrus periods are associated with ovulations. If they are not, the bitch may be having a split heat. When she does ovulate, she should be fertile. Split heat is most frequently associated with young or pubertal bitches; it is therefore advisable to wait until the bitch is two to three years old before intervening.
Does the uterus have time to involute? In bitches that cycle every four months or less and ovulate, the uterus may not have time to recover from the previous cycle. A uterine environment that cannot support a pregnancy may develop. In such cases, one approach to management is to suppress estrus with mibolerone (Cheque®--Upjohn), an androgenic compound, administered orally for six months. Suppression of estrus will allow the uterus to involute completely. The bitch should be bred when estrus recurs after withdrawl of the drug.
Estrus is considered prolonged in a bitch that has behavorial signs of estrus for longer than 21 days. Possible causes include an estrogen-secreting ovarian tumor or cyst (TableIII). Abdominal ultrasonography can be used to observe ovarian structures. A negative scan does not rule out such a problem, however, and exploratory surgery may be necessary to visualize the ovaries. Another possible explanation in cases of apparently prolonged estrus is that the bitch may have vaginitis, in which case she may attract males, and this may be mistaken for a sign of estrus. Vaginitis can be differentiated from estrus by vaginal cytology.
Differential Diagnosis for Apparent Infertility in a Bitch with Abnormal Estrous Cycle
Long interestrous Interval Silent heat
Underlying systemic disease Short interestrous interval
(e.g., hypothyroidism) Prolonged estrus
Split heat Ovarian cyst or tumor
Failure of uterine involution Vaginitis (apparent estrus)
Original Doc: INFERTL0.WPD
Another Treatmet for Swimmers
By Keith G. Bates
Swimmers seem to occur without a pattern. In other words, you cannot predict in what litter they will occur. It seems also that there is one critical time in the puppy's development when it will either get up on its legs, or it will become a swimmer. The following is a technique that has worked many times, both in Scottish Terriers and in other short legged breeds. In fact, a variation was used on the front legs of an Irish Setter.
The swimmer is usually fat, well-fed, and lazy. After a few attempts to get on its feet, it is just content to lay like a turtle, eat, and sleep. It is at this juncture that you must act.
You will need the following: Three-quarter and half-inch adhesive tape, scissors, and if you have access to it, ether. The purpose of the ether is to make the tape very sticky. It goes without saying, that this procedure should be out in a well ventilated space, with no open flames or electrical contacts that will spark. Ether is very flammable and dangerous.
Cut two sections of three-quarter tape about four inches long, and two sections of half-inch tape about two inches long. Cut one piece of three-quarter tape long enough to fit around the puppy as a belly band twice. Wet the tape with ether and fashion "swim fins" on each of the puppy's rear feet with the three quarter tape. Use the short half-inch tape to go around the wrist of the foot to hold the fins in place. Place the feet in a position as if the puppy were lying with the back feet under it, and tape in place with the belly band. If you have help, you can tape the belly band through the folded end of the fins. It holds better that way.
The result is that you have a very angry puppy that is straining to get its feet out of the fins by pushing against them, which is what you want. Put the puppy back with the litter. You might use some Tabasco sauce on the tape to keep the others from chewing on it.
Change the tape every two days. The puppy will walk in four days.
Reprint permission given by the author for the Scottie File Project
Original Doc: swim15.doc
Canine Mycoplasma: its Role in Reproductive Disease
by Janice Cain, DVM and
Melissa Goodman, DVM
Source: NEWS, A Newsletter from International Canine Genetics, Inc., Febraury 1994, pp. 1, 4.
Mycoplasma infections have been implicated as a cause of infertility in both bitches and stud dogs. As a result, mycoplasma continues to receive attention as a potential concern for purebred dog breeders. The following article discusses what is currently known about canine mycoplasma infections and outlines a management approach for breeding animals.
What is Mycoplasma?
Mycoplasmas are bacterial organisms that, because of their extremely small size, have been placed in a separate class. Also, unlike any other bacteria, mycoplasmas lack a rigid cell wall which makes them unaffected by antibiotics that act by invoking cell wall damage (for example, penicillin). Mycoplasmas are extremely fastidious organisms that are difficult to culture without special media, and even then may be difficult to recover. Ureaplasmas are a distinct type of mycoplasmas that have been subclassed and are identified by their own name.
Mycoplasma as Part of the Normal Flora
Several mycoplasma species have been found to be normal inhabitants of the upper respiratory and genital tracts of dogs and cats, and as a result they can be routinely isolated from oral, nasal, conjunctival and genital mucous membranes. Several studies have specifically looked at the frequency of mycoplasma recovery from the genital tracts of fertile versus infertile bitches and stud dogs, and no significant difference has been found., Therefore, recovery of mycoplasma from a vaginal or semen culture does not always correlate to reproductive disease, and likewise does not always need to be treated. Since these organisms exist in the respiratory tract as well as the reproductive tract, aerosol transmission from dog to dog (airborne, licking, sniffing, etc.) is probably more frequent than veneral transmission.
When to Worry About Mycoplasma?
While mycoplasmas may be normal inhabitants of the reproductive tract, they have been associated with infertility, lesions of the reproductive tract and sperm abnormalities.'' As with many opportunistic pathogens (organisms that may cause disease but frequently don't), clinical disease often results when an animal is under stress and/or exposed to high numbers of organisms. Close intensive housing conditions (as in a large kennel or at indoor dog shows) provide the opportunity for high numbers of organisms to develop. A healthy dog or bitch especially if housed individually, however, may not become diseased even after known exposure to the organism.
It has been found that the administration of broad spectrum antibiotics may suppress many other bacteria that make up normal flora and allow mycoplasmas to overgrow. Therefore, the prophylactic use of antibiotics prebreeding is not recommended as it may actually create a pathogenic state, and may contribute to the development of antibiotic-resistant populations of organisms.
A mycoplasma culture should be performed if:
1) A dog has missed several bitches (i.e., no conception).
2) A semen evaluation shows morphologically abnormal sperm cells.
3) A bitch has not conceived having been bred to a fertile stud dog on appropriate days.
4) A dog or bitch produces conception but has a documented high rate of fetal resorption.
It is important to remember that there are many other causes of the above problems, and so a mycoplasma culture should be only one part of a thorough diagnostic investigation performed by a veterinarian experienced in canine reproduction.
Proper Mycoplasma Culture Technique
Due to their fastidious nature, mycoplasmas require special techniques for successful growth in cultures. As a result, mycoplasma cultures should only be sent to laboratories competent in the recovery of the organism. It is recommended that ureaplasma is cultured for at the same time, since it is a similar organism and has also been implicated in infections of the reproductive tract.
Proper technique in obtaining the sample to be cultured is also extremely important. In bitches, it is recommended that the vaginal area close to the cervix be sampled using a guarded swab. In stud dogs, it is important that a semen specimen be collected using sterile technique, avoiding urethral contaminants.
What to do about Normal Fertile Dogs and Bitches?
Since mycoplasma is frequently cultured from the vagina of normal fertile bitches, routine prebreeding cultures of bitches are not warranted. Since mycoplasma is frequently recovered from cultures of the prepuce and/or semen of normal fertile males, routine prebreeding cultures may show some growth of mycoplasma as part of the normal flora. However, some owners may choose to periodically have a dog's semen cultured for mycoplasma. While a negative result is definitive, the significance of a positive result must always be determined by correlation to semen evaluation and clinical condition. Unfortunately, a dog's fertility status cannot be determined on the basis of mycoplasma recovery.
Mycoplasma infection is only one of many factors that may inpact canine fertility. Working with an experienced veterinarian with a thorough, systematic approach to investigating fertility problems will pay dividends to your breeding program.
A guarded swab recommended for proper vaginal culturing in bitches is available through ICG. Veterinarians may order the Accu-CulShure® Specimen Collection/Transport System by calling ICG at 800-248-8099.
Dr. Janice Cain is a Diplomate of the American College of Veterinary Internal Medicine and maintains a referral practice in small animal reproduction and internal medicine at Oak Meadow Veterinary Hospital in Los Gatos, CA.
Dr. Melissa Goodman is Vice President of Veterinary Services at International Canine Genetics, Inc., Malvern, PA.
Doig PA, Ruhnke, HL, Bosu WTK: The genital mycoplasma and ureaplasma flora of healthy and diseased dogs. Can J Comp Med 45:233-238, 1981.
Bjurstrom L, Linde-Forsberg C: Long-term study of aerobic bacteria of the genital tract in stud dogs, Am J Vet Res 53:670-673, 1992.
Lein DH: Mycoplasma infertility in the dog: diagnosis and treatment. Proc SFT, Sept 1989, p. 307-313.
Holzmann A, Lager G: Experimentally induced mycoplasmal infection in the genital tract of the male dog. Therio 7(4): 167-188, 1977.
Lingwood CA et al: Common sulfoglycolipid receptor for mycoplasmas involved in animal and human infertility. Biol of Reprod 43:694-697, 1990.
Strom B, Linde-Forsbert C: Effects of ampicillin and trimethoprim-sulfamethoxazole on the vaginal bacterial flora of bitches. Am J Vet Res 54(6):891-896, 1993.
Original Doc: mycopl.doc
Answering The Alarm: Knowing when a c‑section is necessary
By Chris Walkowicz
GAZETTE, Breeders Forum, July 1989, pp. 26-27.
In most emergencies, we are fortunate to have policemen, fire fighters or medics to aid us. Sirens and alarms alert us to danger.
Unfortunately, we're often alone with a bitch in labor when we face a red alert. The lives of a precious dam and her babes all depend on timely, accurate decisions made by breeders to sound the alarm. It's up to us to be their lifesavers. Our instincts will aid a veterinarian's diagnosis.
Females of all breeds occasionally undergo cesarian sections, especially those who sometimes have an incorrectable malpresentation or those delivering one‑pup litters, such as toys. Not all c‑sections are emergences, however.
Bulldogs‑‑and similarly built breeds who are not constructed for free whelping‑‑certainly make up the greatest percentage of these canine patients. The dam's deep chest presents an uphill climb for the fetuses to reach the pelvis, and contractions may not be forceful enough to provide the oomph needed. Bulldogs are also large‑bodied bitches with narrow hips attempting to deliver pups with huge heads‑‑it's like squeezing the circus fat lady into the tightrope walker's leotards. Something's gotta give. By the time the mama Bulldog reaches parturition, it's a near impossibility for her to assist in the delivery‑‑to tear the sacs, chew cords or lick a pup to lusty, lung‑filling, life‑giving cries. It's time to call the medics. Therefore, the c‑section has become fairly routine for Bulldogs as well as for a few other similar breeds.
The dam's delivery date can thus be pinpointed fairly accurately, and when her temperature drops around the calculated day, breeders know delivery is imminent. That's when the red light begins flashing in the breeder's mind. A c-section is rarely done before the temperature lowers.
Veterinarians find it convenient to deal with planned cesarians. The clinic is notified as much as 24 hours in advance and can schedule the surgery during office hours when staff members are available to assist. Breeders often seek out a vet who is knowledgeable of the breed's - and the breeder's - particular needs.
Just prior to surgery, some vets administer a tranquilizer or very short-acting barbiturate followed by insertion of a tube down the windpipe for anesthetic gas, but others merely use a narcotic/tranquilizer combo, such as Innovar-VetR. Some use a narcotic (morphine) alone, plus a line block (novocaine along incision). Intravenous saline solutions may be administered to replace fluid loss and to prevent shock.
Alive And Squirming
Surgery, using the above lighter anesthetics, can be performed rapidly, with pups delivered alive and squirming. This is in contrast to the effects from the old, deeper barbiturate, which often caused lethargic or even stillborn pups and a sedated dam. Brachycephalic breeds. such as the Bulldog or Pekingese, as well as certain sighthound and toy breeds, are sensitive to some anesthetics. Dogs, like people, have varying responses to anesthetics and it's wise to discuss which is best for your breed with a vet.
Following delivery, mom Bulldog can be given a reversal shot for the narcotic, especially when morphine is used. With this method, she may even walk out to the car with her babes and owner! Due to selection for pain tolerance in their ancestors during development of the breed. Bulldogs seem to have little discomfort with the abdominal incision.
For other breeds, however. it's traumatic to wake up suddenly with a major abdominal incision. A slow waking from a deeper tranquilizer over a period of 12 hours helps those bitches adjust to the discomfort. Another advantage of the "nap" surgery for Bulldog breeders is the convenience of being able to place the pups with the mother upon arrival at home.
Monitor Mom And Pups
Bulldog pups evidence their outlook on life early, often finding it too troublesome to crawl across the whelping box for food and warmth. Because of this and other troubles‑‑such as heavy, clumsy moms who can easily squash a pup‑‑most serious Bulldoggers use a human infant incubator to control temperature and humidity for the fragile babies. Conscientious owners stay on 24‑hour duty during the intensive care period.
But no matter what the breed, pups must not be placed with a dam that is still under the influence of anesthetic and that may be disoriented. A warning grumble should be taken seriously, much like a five‑alarm fire. When the bitch is still groggy, nursing times should be allowed only with the owner present policing the mother's reaction.
The best approach is to send the new family home after surgery so the breeder can monitor feedings until the mother has accepted her brood. Don't leave your bitch and pups at the vet's after a c‑section unless a full‑time, around‑the‑clock staff is available to observe the dam's reaction to the pups as carefully as you would. Since labor contractions aid the maternal instinct, it may be lacking for a time following a c‑section, especially in first‑time mothers.
Because contractions also aid in bringing down the milk, pups may have to be supplemented in addition to nursing on mom's all‑important colostrum. If this is necessary, supplementation should continue until the milk is flowing freely and the dam is completely awake.
Whether surgery is planned or not, any breeder must be prepared for an emergency. There will be no alarms ringing. Only the subtle signs of your canine friend and the pounding of your heart will signal the alert.
Ms. Walkowicz has been a breeder since the early 1970s. Her column was honored with a 1988 DWAA award, and her most recent book, Atlas of Dog Breeds, will be published this year.
In general, dogs rarely have reproductive issues, and most pet owners are concerned with preventing reproduction rather enhancing it. However, for today's serious breeder of pure-bred dogs, there are an amazing variety of reproductive diseases and problems that can occur. For the veterinarian to treat the problems, a complete history and physical examination, as well as a reproductive history and evaluation of the reproductive tract, must be performed.
INFERTILITY IN THE STUD DOG
When dealing with infertility, both the dog and the bitch must be considered. Ninety percent of infertility is due to poor breeding management, such as breeding at the wrong time or not breeding often enough; additionally, the male could have poor sperm quality. Acquired infertility is very common in the dog-if more than a couple of months have passed since the dog's last litter, he may now be infertile. Illness before, during, or after breeding could explain why the bitch did not conceive; likewise, a fever or other illness can adversely affect semen production, and it takes about 60 days for the sperm cells to regenerate after such an insult. A breeding soundness examination can be conducted to evaluate the stud dog; it typically includes a general physical examination and an in-depth examination of the external genitalia. Abnormalities such as severe arthritis or spinal problems may not allow a dog to mount. Hormonal diseases such as Cushing's disease can also reduce fertility. The penis and prepuce should be examined for irregularities, such as a persistent frenulum, growths, or inflammation of the prepuce (posthitis), that may prevent normal intromission. The os penis should be palpated for fractures. Abrasions or lacerations on the penis may bleed during coitus, causing blood to be in the semen. The prostate should be palpated via the rectum; inflammation of the prostate (prostatitis) may be painful and can prevent the dog from finishing mating or make him appear to have a lowered libido. White blood cells (WBCs), red blood cells, and bacteria from the prostate may damage sperm viability. Also, an infection in the prostate can potentially ascend to cause an infection in the testicles (orchitis). The scrotum, testicles, and epididymides are also palpated. The size of the testicles correlates with the amount of sperm seen on collection of an ejaculate: Small, soft testicles are often associated with poor semen quality, greatly enlarged testicles suggest an infection, and lumps in the testicles are suggestive of tumors. Scrota[ abnormalities, such as dermatitis, may adversely affect sperm quality.
An ejaculate of semen should be collected and evaluated for color, volume, total and progressive motility, concentration, and shape (morphology), and the total number of normal sperm should be calculated. There are three distinct outcomes of a breeding soundness examination: (1) normal sperm parameters, (2) abnormal sperm parameters, and (3) no sperm seen in the ejaculate. Volume varies with the amount of prostatic fluid collected but is generally 2 to 20 ml. Sperm motility should be evaluated immediately, and normal dogs should have 75% to 80% progressively motile sperm (i.e., sperm that are moving in a forward direction). A sample of the sperm should be prepared for microscopic evaluation. It is important that the shape of the sperm be evaluated so that the total number of normal shaped progressively motile sperm inseminated is known, as only these will fertilize an oocyte or egg.
Sperm concentration (number of sperm/ml) can be determined by using a special sperm cell-counting device (called a densimeter) or other methods. The total number of sperm in the ejaculate is calculated by multiplying the concentration by the volume; normal is about 10 x 101 sperm/lb of body weight. Therefore a small dog can be expected to produce about 20 x 106 sperm ejaculate and a large dog about 70 x 106. Infertility is very rare in dogs with normal semen parameters. Management problems and bitch infertility should be considered when sperm findings are normal.
If abnormal sperm parameters are found, the dog should be rechecked in 2 to 3 months to see if the problem is transient. The veterinarian should be informed of any recent illness and any medications (especially anabolic steroids) that the dog has received. Although the actual cause for abnormal sperm parameters is often never found, possible causes, including inflammation of the scrotum, testicular neoplasia, trauma, and brucellosis, should always be ruled out. Inflammation of the scrotum can cause a high scrotal temperature that is deleterious to sperm production. An ultrasound of the testicles can be performed to evaluate for testicular neoplasia, as some tumors of the testicle are not palpable. This problem can be treated-a unilateral castration of the affected testicle often restores normal sperm parameters. If no inciting cause of the sperm abnormalities can be found, the case becomes very frustrating for both the owner and the veterinarian.
The absence of sperm in the ejaculate (azoospermia) can have three possible causes: (1) the dog's testicles are not making sperm, (2) the testicles are making sperm, but the sperm cannot get out because the epididymides are blocked, and (3) the testicles are making sperm (which can get out), but a complete ejaculate was not collected. When there are no sperm in the ejaculate, the fluid can be tested for alkaline phosphatase, which is made by the epididymides. A high level of alkaline phosphatase indicates that epididymal fluid was collected. If epididymal fluid was collected and there are no sperm, it is likely that the testicles are not producing sperm. A low level of alkaline phosphatase indicates that the epididymis is blocked or that a complete ejaculate was not obtained. In this case, repeated samples should be collected and an estrous bitch can be used as a teaser to obtain an ejaculate. A careful palpation and ultrasonography of the epididymides should be performed to detect any abnormalities. If the azoospermia persists, a testicular biopsy can determine whether the testicles are producing sperm; however, this procedure is rarely performed. The biopsy procedure itself may severely damage the testis, and it does not seem to matter whether the testes are producing no sperm or sperm are being produced but cannot get out-neither condition is treatable.
INFERTILITY IN THE BITCH
The most important aspect of evaluating infertility in the bitch is the history. The main purpose of the history is to ascertain if there is a problem with cyclicity, management, or the stud dog or if the apparent infertility is actually pregnancy loss. There are basically two types of bitches: those that cycle normally and those that do not.
The Bitch with Normal Cycles
Bitches that cycle normally generally have a 5 to 10 month interestrous interval. The quality of the breeder's history depends on the quality of the breeder's records. Most breeders have a pretty good idea of what is going on, but it often takes careful questioning to bring it out in an orderly, understandable manner. The purpose of the veterinarian's questions (see box on this page) should be to find out whether the bitch was bred at the right time.
A general physical examination of the bitch, an examination of the vulva, and a digital examination of the vestibule and caudal vagina should be performed. Vestibular strictures may prevent normal intromission by the penis and cause an outside tie (i.e., when the bulbus glandis engorges before entering the vagina and is thus too large to fit through the vulva) or may cause the bitch so much pain that she will not allow breeding. Vaginal anomalies including a persistent septum (a band of tissue dividing the vagina into two parts), segmental aplasia (a missing portion of the vagina), or a persistent hymen may be present. Such problems can sometimes be surgically corrected. Although not of much importance themselves, the presence of abnormalities in the vulva, vestibule, or vagina may suggest irregularities in the remainder of the reproductive tract.
Exploratory abdominal surgery (laparotomy) or contrast radiography may help assess abnormalities in the more cranial portions of the reproductive tract (e.g., cervix, uterus, oviducts, ovaries). Vaginal prolapse may preclude normal penetration by the male. Vaginal hypertrophy (enlargement of the vaginal floor) may occur during estrus and interfere with natural mating. A culture may be taken from the vagina, but results are essentially meaningless in the absence of clinical signs of vaginitis (discharge, odor). Aerobic bacteria may be cultured from the vagina of all normal bitches, and Mycoplasma is present in 80% of normal, fertile bitches. Other than Brucella canis, any organism cultured in the absence of clinical signs is considered a normal inhabitant of the vagina. The only bacterium that would indicate a cause of infertility on vaginal culture is B. canis; however, B. canis requires special culture conditions. Many stud dog owners require vaginal cultures prior to breeding because they are concerned particularly about Mycoplasma; they hope to prevent infertility in the stud dog by preventing him from mating with an infected bitch. However, Mycoplasma is a normal inhabitant in 70% to 80% of dogs and bitches, and treating a perceived "infection" in an infertile dog does not restore fertility.
If the physical examination is normal and a management prob lem cannot be detected, the veterinarian may wish to follow the bitch through a complete cycle to ensure that she is cycling normally, has a normal rise in progesterone and normal luteal phase (evaluated by testing progesterone levels throughout the 2 months after the heat cycle), and, most importantly, was bred at the optimum time. Remeber, the potential fertility of a bitch cannot be evaluated unless she is bred to a fertile male. Was the male impregnating other bitches that were bred around the same time as the one that failed to conceive? When was the stud dog's last litter? Was the stud dog sick in the 2 months prior to breeding this bitch? If a solid history of the male cannot be obtained, a breeding soundness examination should be performed on the bitch. Management problems should be corrected, and an optimum breeding management program should be outlined with the help of a veterinarian. As mentioned, the best follow up is to have a veterinarian who is interested in canine reproduction follow the bitch through the next heat cycle. This, along with serial progesterone levels and serial vaginal cytology, will pinpoint the optimum time to breed the bitch.
The quality of the breeding can be important. A natural tie is the best guarantee of a successful in- semination. In cases of an outside tie, the tip of the penis can be held tightly by the handler just behind the glans and a fairly normal ejaculation should occur. Conception rates can be normal with outside ties. Artificial insemination is only as good as the person performing it. Although the technique is very simple in dogs, once the sperm is outside the dog, it is exposed to many insults including mishandling, toxins, cold or heat shock, and improper insemination techniques. Breeders should determine how experienced the inserninator is and what his or her pregnancy rate is; a good inseminator should have a pregnancy rate approaching that of natural breeding. Conception rates with chilled extended semen and frozen semen remain disappointingly low, and these are not recommended for bitches with infertility problems. If a bitch was bred with one of these methods and did not conceive, breeding should be tried again using fresh semen before suspecting that she has a fertility problem.
A possible but not well-documented cause of conception failure and/or pregnancy loss is subclinical uterine infection. Signs include vulvar discharge during diestrus and apparent embryo loss after a positive ultrasound. Treatment can include prophylactic antibiotics on the next heat cycle. Enrofloxacin is administered from the first day of bleeding until 1 week after the last breeding. Cephalexin is then administered until whelping. These bitches should have ultrasonograms to detect pregnancy 30 days after the last breeding.
The Bitch with Abnorinal Cycles
The bitch with abnormal estrous cycles may have no cycles, long interestrous intervals, or short interestrous intervals. A bitch that is less than 2 years old and not cycling may not have reached puberty yet. Some large-breed bitches do not have their first heat cycle until they are 2.5 years of age or older. Some medications such as progesterone, androgens, and glucocorticoids can interfere with cyclicity. A karyotype should be performed on any bitch over 3 years of age that has not had a cycle to determine if there is a chromosomal abnormality. If there is an abnormal chromosome, there is no hope for fertility.
Because some bitches do not show signs of heat that are recognizable to an owner, especially if no male dog is present, progesterone concentration should be determined. A high level (>2 ng/ml) indicates that she has been in heat within the last 2 months. The test should be repeated approximately 2.5 months later, by which time the progesterone level should have returned to baseline (<2 ng/ml). If progesterone is still high in the second sample, possible ovarian abnormalities (e.g., a luteal cyst or ovarian tumor) may be present; this can be evaluated by ultrasound or laparotomy. Luteal cysts are rare but could respond to prostaglandin therapy. Unilateral and nonmetastatic ovarian tumors can be removed, which could possibly restore fertility. Cushing's disease may cause elevated progesterone levels and should be tested for in the bitch with persistently high progesterone levels.
A link between thyroid function and infertility is not clear, although there were reproductive problems in one kennel of hypothyroid dogs. Thyroid function can be tested; if the bitch is found to be hypothyroid, thyroid medication can be administered. However, if a bitch's infertility is due to hypothyroidism, she should not be used for breeding. If thyroid levels are normal, the veterinarian should have blood samples evaluated for luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels. If the levels are high, the bitch is not receiving feedback from the ovaries, which indicates gonadal dysgenesis or primary ovarian failure.
Long interestrous intervals (i.e., over 10 months) may be a normal variation, especially in larger and/or older bitches. There is no good way to bring a bitch into a fertile heat cycle, so the breeder will have to wait for her to cycle. Thyroid function can be checked as for the bitch with no cycles.
Short interestrous intervals may lead to infertility because the uterus does not have enough time to return to its normal size and shape (i.e., involute) after whelping or the previous heat cycle. The interestrous interval can be lengthened by treating the bitch with megestrol acetate* for 32 days. Treatment should begin a few weeks before she is expected to come into heat. That expected heat cycle will not occur, and the bitch should come into a heat 4 to 6 months after the end of megestrol acetate treatment. The bitch can be bred on this cycle and may be fertile if shortened interestrous intervals were her only problem. Because megestrol acetate is a synthetic progestogen, its use may be associated with an increased risk of endometritis and pyometra, as would be seen with any endogenous or exogenous progestogen; however, the percentage of bitches affected is small.
Short interestrous intervals seem to relate to inadequate luteal phase. The progesterone level continues to rise after ovulation but drops to baseline after 1 month to 6 weeks. The normal luteal phase is 60 to 70 days. An inadequate luteal phase is documented by serial progesterone samples every few weeks throughout pregnancy. The progesterone level should remain above 4 to 5 ng/ml for 60 days. If documented luteal insufficiency exists, the bitch can be supplemented with progesterone in oil for 56 to 58 days after ovulation. Progesterone must be discontinued at that time to allow normal whelping.
Split heats occur when a bitch grows follicles on her ovaries and experiences the signs of proestrus (swollen vulva, vulvar bleeding, attractiveness to males) but does not progress into estrus and does not ovulate. The bitch's follicles will usually regress, and then she will come intoa complete heat cycle with ovulation anywhere from 2 to 12 weeks later. Split heats are most common in a young bitch, especially at her first season, and are not considred to be associated with infertility when bred on the cycle in which ovulation occurs. Split heats must be differentiated from short interestrous intervals between two true heat cycles. A vaginal smear will show red blood cells and intermediate and superficial cells as would be expected during proestrus but in a split heat will not progress into an estrus smear (anuclear superficial cells). If vaginal smears are collected for a suffi- cient time, they will change to an anestrus smear characterized by parabasal cells and WBCs. The vaginal smears for true heat cycles with shortened interestrous intervals will progress normally.
Periparturient diseases can be seen prior to, at the time of, and soon after whelping. One of the most common problems reported by breeders is false pregnancy or pseudocyesis. This condition occurs during the luteal phase (diestrus), which is the progesterone-dominated phase that all bitches experience after an estrus or a heat cycle. Because of thesimilarity between the hormonal profiles of pregnant and nonpregnant bitches, many of the changes seen in the pregnant bitch are also seen in the nonpregnant bitch. These physical changes include mammary gland growth, abdominal enlargement, and lethargy. In addition, if the progesterone level falls rapidly in the nonpregnant bitch, as would occur at whelping, the behaviors associated with parturition (nesting, lactating, "adopting" objects and trying to nurse them) may be seen. Generally, no treatment is needed or recom- mended; however, when necessary, such as in cases of destructive nesting behaviors, mibolerone or an antiprolactin agent such as bromocriptine may be used.
Abortion or resorptions can be caused by many different factors; even when the aborted fetuses and/or placentas are available for evaluation, the exact cause of pregnancy failure may not be understood. It is extremely difficult to accurately assess the number of abortions or resorptions because there is no way to confirm pregnancy during the first 4 weeks of gestation. Also, ultrasonography or radiography to detect pregnancy is not performed in most bitches unless there is a problem or suspected problem. In general, the causes of abortion/resorption can be divided into fetal defects, maternal problems, infectious diseases, and endocrine or hormonal causes.
Any defect in fetal development that is not compatible with life will result in abortion/resorption. Defects in the fetus can be caused by chromosomal abnormalities or major organ defects or can result from the use of medications that cause defects in the developing embryos (called teratogens). A wide variety of commonly used medications and chemicals can cause defects in the fetus, especially in early pregnancy.
Numerous infectious agents have been implicated in causing uterine disease, fetal death, and abortion. The bacterium B. canis is the only documented infectious agent that causes infertility, al- though other pathogens have been associated with absorption/resorption. This disease is spread by contact with infected body fluids and causes infertility, abortion, and stillbirth. Transmission of B. canis occurs readily across mucous membranes, allowing dogs to be infected by oral, nasal, conjunctival, or venereal exposure. Its presence in a kennel is disastrous; however, the estimated incidence of dogs and bitches infected with B. canis in the United States is 1 % to 6%.
All dogs and bitches should be tested for brucellosis prior to breeding. The most common test (rapid slide agglutination) has a moderate false-positive rate. Therefore dogs testing positive on this test should have additional tests performed to rule out false-positive results. Dogs that still test positive should have blood cultures and lymph node aspirates performed.
The B. canis-infected, aborting bitch is highly dangerous to noninfected dogs. Aborted placental tissues and fluids contain huge numbers of the organism, which can rapidly spread through a kennel. The most important sources of infection include vaginal discharges, aborted materials, semen, and urine. The clinical signs of brucellos, are late-term abortions and stillbirths in females and inflammation of the epididymis (epididymitis), inflammation of the testicles, and testicular atrophy in males. Dogs with brucellosis also can have arthritis, generalized lymph node enlargement, an enlarged spleen and/or liver, low-grade meningitis, and inflammation of the eye (uveitis); however, an infected dog may have no obvious clinical signs, illustrating the imiportance of regular testing of all breeding stock. The most common sign of brucellosis is abortion in an otherwise healthy bitch between days 45 and 59 of gestation, although the abortion can occur as early as day 30 or the bitch can deliver both living and dead pups. Surviving puppies are infected with the disease.
Treatment of B. canis is largely ineffective; because infected animals can shed the organism for more than 1 year after infection, it is recommended that dogs and bitches positive for B. canis be euthanatized. The only other alternative is to neuter or spay affected dogs, place them on long-term antibiotics, and separate them from other dogs, especially breeding animals. B. canis cannot be eliminated from the prostate of the male, although there has been limited success in clearing the organism from bitches. Additionally, breeders or owners who wish to keep animals that have tested positive for B. canis should be aware that human infections with this bacteria have occurred, albeit rarely.
At present there is no vaccine that protects against B. canis. Prevention depends on avoiding exposure to infected dogs and bitches. In the disease-free kennel, new arrivals should be tested and found to be negative prior to entry. Bitches should test negative within the month prior to breeding; stud dogs should ideally be bred only to bitches that have recently tested negative and should be tested before each breeding (preferable) or at least every 6 months.
Canine herpesvirus (CHV), a common cause of neonatal death, is also thought to be involved in infertility, abortion, and stillbirth in the bitch. Genital vesicles can be present in the nonpregnant bitch. Up to 80% of bitches will be seropositive for CHV, but very few have reproductive problems. Reproductive problems are seen only when a naive bitch is infected during the last 3 weeks of pregnancy or when pups are infected during the first 3 weeks of life. The transmission of CHV may be venereal, transplacental, or respiratory or by vaginal contact during birth. In pups, CHV causes a fatal disease characterized by generalized necrosis and bleeding. The disease is usually mild or subclinical in adults and consists of conjunctivitis, a serous or mucopurulent ocular and/or nasal discharge, and vaginal lesions that start as vesicles early in the course of the disease but then become circular and pock-like. Genital lesions usually disappear shortly after infection but may reappear at the onset of the next proestrus.
A CHV-infected bitch may have dead and/or mummified pups in the same litter as live pups. The placenta from a bitch infected with CHV is typically underdeveloped and has white-gray areas that range in size from very small to that of a grain of rice. Diagnosis of CHV is based on virus isolation, which requires fastidious sampling and culture techniques; a negative result may be due to inadequate technique rather than a truly negative tissue sample. No vaccine is available; the only recommendation is to expose naive bitches prior to breeding.
Other, less common causes of canine abortion include Toxoplasma gondii, Mycoplasma, and Ureaplasma infections. Toxoplasmosis is a rare cause of abortion. Cats are the definitive host; dogs become infected by ingesting infected cat feces or infected meat. Diagnosis is made by two serum samples obtained 3 weeks apart. A fourfold increase in serum titer levels indicates toxoplasmosis infection. Prevention is accomplished by preventing exposure to cat feces and raw meat. Mycoplasma and Ureaplasma, which are normal organisms in the canine vagina, have been implicated in infertility, resorption, abortion, stillbirths, and neonatal death. It is difficult to establish a cause-and- effect relationship because 80% of normal bitches have a positive vaginal culture for Mycoplasma. Just because Mycoplasma can be isolated from a bitch that aborted does not mean that Mycoplasma caused the abortion. Because the organism is a normal inhabitant of the vagina, diagnosis of Mycoplas- ma abortion is, at best, tentative. Mycoplasma- and Ureaplasma-in- duced abortions are rare. Treatment involves the use of antibiotics for 10 to 14 days.
Noninfectious causes of abortion include inadequate luteal function, inadequate diet, and inappropriate administration of medications. Inadequate luteal function or a low progesterone level has not been well documented. Bitches with a history of repeated embryonic resorption, as detected by ultrasonography, have been found to have low progesterone levels in the second month of gestation. Progesterone levels should be above 4 ng/ml. Bitches can be tested for progesterone concentration, and those with low levels can be supplemented with progesterone in oil until 56 to 58 days after ovulation.
Bitches require carbohydrates in late gestation. Those fed a diet deficient in carbohydrates will have an increased incidence of stillbirths.
A wide variety of commonly used medications can cause resorptions and abortions; examples include griseofulvin, tetracycline, glucocor- ticoids, chlorpromazine, carbaryl, diazinon, and phenobarbital. Live vaccine viruses can also be teratogenic and should be avoided during pregnancy. In fact, all drugs should be avoided during pregnancy if possible.
Treatment of a bitch with impending abortion is limited to restricting activity, administering antibiotics, and making sure the progesterone level is adequate. A bitch that has recently aborted should be evaluated for signs of systemic disease and pyometra. Retained and dead fetuses can be diagnosed via ultrasonography and/or radiography. If retained pups are present, the treatment options are spaying or opening the uterus and removing the dead fetuses (uterotomy).
Figure 1. Microscopic section of a normal diestrus uterus. Note the presence of small glands in the endometrium (arrows).
CYSTIC ENDOMETRIAL HYPERPLASIA/PYOMETRA COMPLEX
Pyometra is actually a hormonal disease in the bitch; although a bacterial infection is involved, it is the presence of progesterone and its effects on the uterus during diestrus that allow the infection to occur. Pyometra occurs most often during diestrus, the 60 to 70 day period after the heat cycle when the uterus is under the influence of progesterone (Figure 1). A function of progesterone is to quiet the muscular activity of the uterus and close the cervix. Cystic endometrial hyperplasia (CEH) usually precedes the development of pyometra in old- er bitches, although pyometra can be seen in bitches of any age.
Under the influence of progesterone, the lining of the uterus becomes thicker with cystic areas due to an increase in size and activity of the endometrial glands, which exhibit secretory activity (Figures 2 and 3). The use of synthetic progestogens such as megestrol acetate have many effects that are similar to those of endogenous progesterone and can therefore contribute to the development of CEH. These combined actions of progesterone allow for an accumulation of secretions that permit bacterial overgrowth. A diagnosis of pyometra is made when the bitch has fluid in the uterus (demonstrated by ultrasonography) and an increased WBC count.
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calcium; thus the bitch is unable to meet a sudden need to remove calcium from her bones and her blood calcium level can become dangerously low, leading to the development of eclampsia. Also, diets high in legumes (soybeans) may tie up calcium and should therefore be avoided in the lactating bitch.
The mammary glands are highly modified skin glands located in two parallel rows along the ventral chest and abdomen. Dogs have four to six (usually five) pairs of glands. It is not uncommon to see a missing nipple or pair or asymmetrically placed nipples. Milk is produced from alveoli (secretory cells), which are arranged in clusters called lobules. The milk fills the alveoli and then is drained from the lobules through small ducts. A cluster of 8 to 22 large ducts drain to the outside at each teat.
Mastitis is a infection of the mammary gland that usually occurs within the first week postpartum. The bitch may be ill, have a fever, decreased appetite, and de- pression, and may not allow the pups to nurse. The affected gland is usually warm, firm, red, and painful. Milk from the infected gland is abnormal. Antibiotic treatment is based on culture and sensitivity of the affected gland. If necessary, the pups may be allowed to nurse but should be monitored for weight gain. If the pups develop diarrhea or fail to thrive, they should be removed from the dam and hand raised. If the pups are nursing, the veterinarian should be certain to use antibiotics that do not affect them. Occasionally, the mammary glands form abscesses that need to be surgically drained.
Agalactia or lack of milk is rare in the bitch. There is no good treatment, and pups need to be hand fed or fostered to another bitch. Sometimes a nervous bitch will not allow nursing immediately postpartum; reassurance from the owner may be all that she needs. Tranquilizers may be useful.
Galactostasis is a noninfectious cause of mammary gland engorgement at weaning. Sometimes the mammary glands become large and painful, but the bitches are not ill and the WBC count is normal. Placing cold compresses on the glands and limiting the bitch's food intake may also help.
Questions for Breeders
·When did the bitch come into heat for the first time?
·How often does she cycle?
·Does the bitch allow a male to mount and breed?
·How often is the bitch bred in a cycle?
·When did she stand for the male?
·When did she first refuse the male?
·When was she bred in relation to these times?
·How was the time of breeding determined?
·Was ovulation timing performed by progesterone levels, luteinizing hormone levels, or serial vaginal cytology?
·How many times was the bitch bred?
·When and why was it decided to stop breeding the bitch?
·Were brucellosis titers done on both the bitch and the stud dog within 30 days of breeding?
·How was the bitch bred (natural or artificial insemination)?
·If artificial insemination was used, what type of semen (fresh, chilled, frozen) and insemination technique (vaginal, intracervical, surgical) were used?
·Has the bitch been bred with a male that has successfully sired litters around the same time that this bitch was bred?
·Has the bitch produced any litters, abortions, and/or resorptions?
·If the litter was resorbed, how was pregnancy confirmed?
·Has the bitch even been treated for mismating?
·Has the bitch ever had pyometra, vaginitis, and/or abnormal vulvar discharge?
·Has the bitch ever had medication to delay or prevent a heat cycle?
·Do any other bitches in the kennel have reproductive problems?
·Do any other bitches in her line have reproductive problems?
·Does the bitch or the stud dog have any significant illness?
·Is the bitch or stud dog receiving any medication (including flea and tick control)?
azoospermia-absence of sperm in the ejaculate
dysgenesis---defective embryonic development
epididymis-the elongated, cord-like structure connecting the testes to the ductus deferens, used for transport and maturation of sperm
karyotype-the chromosome characteristics of an individual or cell line
lochial discharge-bloody vulvar discharge that occurs following birth
metritis-minflammation of the uterus
necrosis--death of a portion of tissue or an organ, resulting from irreversible cellular damage
teratogenic-referring to an agent that causes deformity in the developing fetus
tetany--a sustained muscular contraction caused by a series of stimuli repeated so rapidly that the individual muscle responses are fused; characterized by muscle spasms, cramps, and twitching
vaginitis-inflammation of the vagina, characterized
by pain and a purulent, bloody, or watery discharge
vesicle-small, fluid-fllled sac (similar to a blister)
· Although relatively rare in dogs, an amazing variety of reproductive diseases and problems can occur. Providing the veterinarian with a complete reproductive history will assist in making a diagnosis.
· Although most infertility in stud dogs is related to poor breeding management, a breeding soundness examination can identify potential causes of infertility.
· Infertility in the bitch can be due to cyclicity problems, breeding management, or infertility
in the stud dog; on the other hand, apparent infertility may actually be pregnancy loss.
· Brucella canis, the causative agent of brucellosis, can cause infertility, abortions, and stillbirths in dogs, and all dogs and bitches should be tested for brucellosis prior to breeding.
· Cystic endometrial hyperplasta-pyometra complex can manifest as open-cervix pyometra, which is responsive to medical treatment, or closed-cervix pyometra, in which case spaying is recommended.
· Several postpartum problems can occur, and some can cause serious illness; most are rare,
but owners need to be attentive to the bitch after whelping to detect potential problems.
Feldman EC, Nelson RW: Canine and Fe- line Endocrinology and Reproduction, ed 2. Philadelphia, WB Saunders, 1996, pp 525-733.
Hinrichs K: Therfogenology: A Course Syl- labus. North Grafton, MA, Tufts Univer- sity School of Veterinary Medicine, 1997, pp 183-217.
Marrow DA: Current Therapy in Theri- ogenology, ed 2. Philadelphia, WB Saunders, 1986, pp 466-476, 484-490, 505-509,511-515,539-541,544-552.
ABOUT THE AUTHOR
Dr. Dornit earned her DVM from Tufts University School of Veterinary Medicine in 1996 and then completed an internship in theriogenology (reproduction), also at Tufts University. She is currently a consultant in small animal reproduction at Tufts and works in private practice in Danvers, MA.