Breeds Affected: Many breeds, especially Border Collie, English Springer Spaniel, Greyhound, Irish Wolfhound, and Labrador Retriever
Samples Accepted: Blood, Buccal Swabs
Disease Information: Also known as Canine Stress Syndrome, dogs affected with MH develop an elevated body temperature, muscle contractions and rigidity and sometimes seizures. Affected dogs appear generally healthy, but under stressful situations can manifest the disease. Most importantly, exposure to anesthetics and muscle relaxants stimulate MH, making it very important to know if animals are normal before surgery or medical treatment.
Inheritance Information: MH is autosomal dominant, meaning that animals with just one copy of this allele will be affected. 50% of their offspring will also be affected.
The possible genotypes are:
n/n The dog is normal, and cannot produce affected offspring.
n/MH The dog is affected, and 50% of the offspring will be affected.
MH/MH The dog is affected, and 100% of the offspring will also be affected. Dogs homozygous for MH are more severely affected than heterozygotes.
– Affected animals (n/MH, MH/MH) should not be used for breeding.
Test Information: This mutation test identifies a single base pair change in exon 15 of the RYR1 gene.
Roberts, M.C., Mickelson, J.R., Patterson, E.E., Nelson, T.E., Armstrong, P.J., Brunson, D.B., Hogan, K.: Autosomal dominant canine malignant hyperthermia is caused by a mutation in the gene encoding the skeletal muscle calcium release channel (RYR1) Anesthesiology 95:716-725, 2001. Pubmed reference: 11575546.
Further information is available at the Online Mendelian Inheritance in Animals website.