This web page is a fully automated, five-generation Genetic Risk Calculator. The calculator is based on formulas presented in Dr. Jerold Bell’s article “Relative Risk Pedigree Analysis“. The calculator is a stand alone version and is not tied into any specific database. Each user will have to follow the instructions in the program in order to input Carrier (C), Sibling to Affected (SA) or Sibling to a Carrier (SC) status that is known in order to calculate final predicted genetic risk. Note: You will find that the new calculator is not exactly the same as the former version. You will have to research the Scotties in the pedigree, locating any Affected individuals on your own and making note of the obligate Carriers (both sire and dam and all offspring) connected to that individual. You will be responsible for the all data entered, and the calculator will do the math for you.

  • The results obtained from this calculator are statistical predictions based on simple Mendelian inheritance and do not provide a certainty of outcome from any individual breeding. The STCA is providing this tool for breeders interested in pedigree analysis of a potential breeding and is not responsible for the validity of data input or breeding outcomes. Comments or suggestions for improving the calculator may be sent to the webmaster using the Site Feedback link on the bottom of the page..
  • Simplified instructions for using the calculator are at the bottom of the page, below the Results block.


Please Note: This is a general purpose Carrier Risk Assessment Calculator.
Limitations:  This page should be used with caution if both the Sire and the Dam in any mating have a Carrier Status Code, or if the pedigree needs 5 or more codes. Typically, it is not necessary to add any codes behind a dog that has been assigned a Carrier Status Code. A message will appear if this is attempted.

How to Enter Carrier Status Codes:

  1. Start by making sure the calculator is reset.  All Carrier Status Codes should be “Unknown”.
    • The Reset button at the bottom of the calculator can be used to reset the calculator.
  2. Use the light colored (light Green and Yellow) cells below Sire and Dam blocks to record the carrier status of any Sire or Dam in your pedigree.
  3. Choose one of the following codes from the drop down in each cell.
    • “C” = Obligate Carrier of the recessive gene under consideration (the dog is a carrier).
    • “SC” = Sibling to an Obligate Carrier.
    • “SA” = Sibling to a dog clinically diagnosed as Affected.
  4. If you make an error, simply change it to the correct value, or Unknown if you do not have data on that dog.
  5. Each time you select a Carrier Status Code, the Affected and Carrier Risks will update automatically.


  • The value A = Affected is not used, because an Affected dog will always produce a Genetic Carrier as its off-spring. Therefore, if your pedigree includes a known Affected dog, please record its off-spring as “C”.
  • If you enter codes you do not need, a message will pop up below or to the right of the code that states it is not needed.