Quick Summary
Phenotype: Affected dogs typically display hair loss and crusty/scaly skin lesions on the face, ears, tip of the tail and/or bony prominences of the legs and feet. Lesions may appear in adulthood or as early as 12 weeks of age. Muscle involvement can happen in more severe cases. Mildly affected dogs may display some muscle loss on the face whereas severely affected dogs can have difficulty eating, drinking and swallowing, and may display abnormal gait.
Mode of Inheritance: Complex Inheritance
Alleles: Genetic variants in 3 loci are associated with the risk of developing dermatomyositis in the Collie and Shetland Sheepdog.
Locus A: A = DMS risk allele; a = wildtype
Locus B: B = DMS risk allele; b = wildtype
Locus C: C = Risk allele (DLA-DRB1*002:01); c = other DLA haplotypes
Breeds appropriate for testing: Collie, Shetland Sheepdog
Explanation of results:
• Dogs with aa and bb, Aa and bb, aa and Bb, or Aa and Bb genotypes are at low risk for dermatomyositis with either CC or Cc genotypes.
• Dogs with aa, Bb and cc genotypes are at low risk for dermatomyositis.
• Dogs with aa, BB and Cc genotypes are at low risk for dermatomyositis.
• Dogs with AA, bb and Cc or CC genotypes are at moderate risk for dermatomyositis.
• Dogs with aa, BB and CC genotypes are at moderate risk for dermatomyositis.
• Dogs with Aa, BB and Cc genotypes are at moderate risk for dermatomyositis.
• Dogs with AA, Bb and Cc genotypes are at moderate risk for dermatomyositis.
• Dogs with AA, Bb and CC genotypes are at high risk for dermatomyositis.
• Dogs with Aa, BB and CC genotypes are at high risk for dermatomyositis.
• Dogs with AA, BB and Cc or CC genotypes are at high risk for dermatomyositis.
• Dogs with aa and bb or BB, Aa and bb or Bb or BB, AA and bb or Bb or BB genotypes with the cc genotype have an unknown risk for dermatomyositis due to limited representation in the study population.
Sample Collection
Dog DNA tests are carried out using cells brushed from your dog's cheeks and gums. Only VGL-provided cytology brushes are accepted for this test. Brushes will be sent to you by mail for no additional charge.
We recommend waiting until puppies are at least three weeks old before testing.
Step-By-Step:
- Make sure the dog has not had anything to eat or drink for at least 1 hour prior to collecting sample.
- When swabbing puppies, isolate each puppy from the mother, littermates and any shared toys for 1 hour prior to swabbing. Puppies should not have nursed or eaten for 1 hour prior to collecting sample.
- If collecting samples from more than one dog, make sure to sample one dog at a time and wash your hands before swabbing another dog.
- Label brush sleeve with name or ID of dog to be sampled.
- Open brush sleeve by arrow and remove one brush by its handle.
- Place bristle head between the dog’s gums and cheek and press lightly on the outside of the cheek while rubbing or rotating the brush back and forth for 15 seconds.
- Wave the brush in the air for 20 seconds to air dry.
- Insert brush back into sleeve.
- Repeat steps 5 - 8 for each unused brush in sleeve on a fresh area of cheek and gums. Make sure to use and return all 6 brushes sent by the VGL.
- Do not seal brushes in sleeve.
- Place all samples in an envelope and return to the address provided.
ATTENTION:
- Do not collect saliva/drool – the key to obtaining a good sample is getting cheek cells on the swab
- Do not rub swab on the dog’s tongue or teeth – this will result in poor quality sample
- Do not collect a sample from a puppy that has recently nursed – the mother’s genetic material can rub off on the puppy’s mouth and contaminate the sample
Dermatomyositis (DMS) is an immune-mediated disorder that affects the blood vessels of the skin and muscle. The disorder is considered complex, being caused by genetic and environmental factors. DMS affects mostly Collies and Shetland Sheepdogs but a DMS-like phenotype has been described in Beaucerons and Corgis.
Affected dogs typically display hair loss and crusty/scaly skin lesions on the face, ears, tip of the tail and/or bony prominences of the legs and feet. Lesions may appear in adulthood or as early as 12 weeks of age. Muscle involvement can happen in more severe cases. Mildly affected dogs may display some muscle loss on the face whereas severely affected dogs can have difficulty eating, drinking, and swallowing, and may display abnormal gait.
A 2017 study identified 3 genes (also referred to as loci) that confer risk for developing DMS in the Collie and Shetland Sheepdog. Locus A consists of a single nucleotide substitution in the PAN2 gene that causes an amino acid change (p.Arg492Cys); locus B consists of an indel in the MAP3K7CL gene (c.383_392ACTCCACAAA>GACT); and locus C consists of a risk DLA haplotype. Below is a table showing the specific genotype combinations of these 3 loci that confer unknown, low, moderate or high risk for developing DMS.
Table 1: Genotype combinations associated with unknown, low, moderate and high risk of developing DMS in the Collie and Shetland Sheepdog.
Testing recommendations: Testing for DMS risk assists owners and breeders in identifying dogs that are at increased risk for developing DMS. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing dogs at high risk for developing DMS.