Canine Malignant Hyperthermia (MH)
Acronym: | CMH, MH |
Gene: | RYR1 |
Mutation: | c.1643T>C |
Inheritance: | Autosomal dominant |
Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Canine malignant hyperthermia (MH) is an autosomal dominant inherited disorder of skeletal muscle characterized by hypercarbia, rhabdomyolysis, generalized skeletal muscle contracture, cardiac dysrhythmia, and renal failure that develops on exposure to volatile anesthetics and depolarizing muscle relaxants. When given these agents, MH-susceptible dogs show tachycardia, muscle contractions, hyperthermia, elevated carbon dioxide production, and death if the anesthetic is not discontinued. Malignant hyperthermia can be triggered in susceptible animals by excitement, exercise, or environmental stress. Because of this reason, this disorder is also known as “canine stress syndrome.”
Canine malignant hyperthermia episodes usually come on unexpectedly and are very serious. If the condition is recognized early enough in an animal under anesthesia, certain measures can be taken in order to be able to save the animal. Some types of anesthesia can be fatal for dogs with malignant hyperthermia allele. This is why it is also important to identify dogs that carry the malignant hyperthermia allele prior to surgical procedures. Unfortunately, regardless of treatment, malignant hyperthermia is usually fatal. Some types of anesthesia can be fatal for dogs with the malignant hyperthermia allele.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
AFFECTED HETEROZYGOTE |
Tested mutation was detected in animal with „affected heterozygote“ result. Animal tested as affected heterozygote has one wild-type and one mutation allele, it is in heterozygous state. It is likely to develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
**Penetrance of tested mutation, and potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Roberts, M.C., Mickelson, J.R., Patterson, E.E., Nelson, T.E., Armstrong, P.J., Brunson, D.B., and Hogan, K. (2001). 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 – 716–725.