Mutants Key to Athletic Prowess

A. “Bully whippet B. Normal whippet

A scientific revelation in canine genetics has provided perplexed breeders with an explanation for the occurrence of mutant whippet offspring. “Bully” whippets, as they are commonly known, have a condition known as ‘gross muscle hypertrophy’ and show symptoms of heavy muscle development, especially in the head and neck region.

Recent research has discovered the deformities to be the result of a mutation in the canine myostatin gene, a protein regulator of the amount and composition of muscle fibres. However, only dogs homozygous for the gene develop into “bully” whippets. Thus, this phenotype displays an autosomal recessive mode of inheritance, as all mutant whippets studied were the result of mating carriers. Whippets with gross muscle hypertrophy are usually euthanized at birth because they do not meet the breed standards of the American Kennel Club.

Interested by the frequent production of mutant offspring in litters of champion racing whippets, scientists undertook further revealing studies. It was found that dogs heterozygous for the mutant myostatin gene are physically superior in the racing industry. Due to their heavier muscling, these whippets are among the fastest in competitive racing events. This is the first time that scientists have linked a mutation in the myostatin gene to athletic prowess. In support of this, the only human mutation of the myostatin gene to be found was discovered in a professional athlete. Evidently, the mutation of the myostatin gene is desirable in heterozygous form, yet is it ethical to breed for superior racing whippets when the production of “bully” whippets will be inevitable?

Mosher, DS, Pascale, Q, Carlos, DB, Sutter NB, Mellersh, CS, Parker, HG & Ostrander, EA 2007, ‘A mutation in the Myostatin Gene Increses Muscle Mass and Enhances Racing Performance in Heterozygous Dogs’, Plos Genetics, vol.3, no.5, pp. 779-786.

Shelton, GD & Engvall, E 2007, ‘Gross muscle hypertrophy in whippet dogs is caused by a mutation in the myostatin gene’, Neuromuscular Disorders, vol.17, pp.721-722.

Lee, S-J 2007, ‘Sprinting without myostatin: a genetic determinant of athletic prowess’, Trends in Genetics, vol.23, no.10, pp.475-477.