Frequently asked questions for the first test results Beta version November 2022
How is it possible that there is a difference in this?
Answer: The risk assessment received by Dr Leegwater gives an estimate of low or high risk for obtaining the disease polymyositis for the direct offspring.
With a low-risk rash, the offspring have a low risk of developing polymyositis. Possible combinations of parents with this rash are homozygous mutant (MM) x homozygous free (WW); heterozygous (WM) x homozygous free (WW); and homozygous free (WW) x homozygous free (WW). Which of the two low-risk genotypes (WW or WM) the offspring may have cannot be deduced from this risk assessment. The genotype of the parents cannot be deduced from this either.
Results that would lead to high risk (MM) (for part of) the offspring were not given. The combinations of homozygous mutant (MM) x homozygous mutant (MM); homozygous mutant (MM) x heterozygous (WM); and heterozygous (WM) x heterozygous (WM) were avoided.
With a risk assessment in Fit2breed, you can enter any desired combination via the test mating button; you will then see a risk assessment for the potential puppies on the right side of the screen.
The warning: “Combination not advised because it increases the spread of PM in the breed” is given if only heterozygous animals (WM) are born from a combination.
For the combination heterozygous x homozygous wildtype you will receive a warning that it is advised to test all puppies in a litter. (50% of animals may be heterozygous). From this litter, puppies can be chosen that are homozygous wild type (free) to continue breeding with.
The fact that a dog is heterozygous does not have to be a problem to use this dog for breeding. Dogs that are heterozygous themselves have a 1% chance of getting sick themselves.
However, if only combinations are made of which the offspring are heterozygous for the PM mutation, there will be more heterozygous dogs within the entire kooiker population. This is undesirable because it limits your possibilities to make a good combination for the future.
In the risk assessment it is always possible, even very desirable, to use a heterozygous dog (WM) for breeding but in combination with a homozygous wild type (WW). As a result, all offspring have a low risk of developing PM themselves.
Update Fit2Breed
From January 2023, all results of the new polymyositis tests will be specified: The results will be accompanied by the following explanation:
WW: Homozygous wildtype
The dog is free of the DNA variant that is involved in the development of polymyositis in the Kooikerhondje. This means that the risk of the disease is extremely low.
WM: Heterozygous
The dog has one copy of the DNA variant that is involved in the development of polymyositis in the Kooikerhondje. This means that the risk is limited; it is estimated that the probability of the disease is 1%.
Combination with another heterozygous or a dog that is homozygous for the risk factor leads to increased risk for some of the offspring and is strongly discouraged. The dog can be combined with a dog that is free (WW). The advice is to test all offspring for the PM risk factor, in order to be able to select animals that are free for the next generation.
MM: Homozygous mutant
The dog is homozygous for the risk factor and has two copies of the DNA variant that is involved in the development of polymyositis in the Kooikerhondje. The dog therefore has an increased risk of getting polymyositis. This probability is estimated at a minimum of 10%. We advise you to have the CP (= CPK) level in your dog’s blood measured during routine visits to your veterinarian. An increased content may indicate polymyositis. Clinical signs that may occur include difficulty swallowing and difficulty walking, with a short, stiff stride.
Combining your dog with a Kooikerhondje that is free of the risk factor (WW) will result in a limited risk for all offspring, but does contribute to the spread of the mutation in the breed (because all offspring will be carriers). Combination with a dog that is not free is strongly discouraged.
In Fit2breed, with a new update of the page “Summary page”, the PM status of a dog will be visible under the heading “DNA test results complex diseases”, if the owner has given permission to share the results in Fit2Breed. A risk assessment for a combination of animals via Fit2breed remains necessary.
In Fit2breed, the summary page of the dog will be adjusted. At the page “By disease” you will find
- monogenetic disorders: VWD and ENM
- complex genetic diseases: PM
There is a possibility to print the risk assessment via Fit2breed and save it as a PDF file. For a breeder it is important to make a risk assessment for each litter. and With this PDF file it can be demonstrated that at the time of covering a certain combination indicates a low risk score and the breeder has used the most up-to-date information available. The breeder can save this PDF file himself but also send it to zooeasy@kooikerhondje.nl to upload this file at the relevant litter (after birth and registration). The risk assessment can change over time, for example if more information becomes available from the dog or family members.