Brett The Vet

EPISODE 7: Genetic Miss

Man has genetically manipulated domestic animals for centuries. Different breeds were artificially created to enhance form and function through specific selection for desirable characteristics. The process can produce spectacular results and much progress has been made in the production and aesthetic sectors of animal husbandry. But the DNA double helix is a splendid and infinitely complex entity which our minds will never comprehend. Our narrow focus inadvertently reveals weaknesses and vulnerabilities that would normally be excluded through natural selection.

In the extremes we have created spectacular features and simultaneously deplorable affliction. There are double muscled beef breeds that struggle to walk and give birth. Hornless milk cows bear giant udders that are proned to damage and mastitis. Broiler chickens reaching maturity in 3-4 weeks, unable to support their own bodies because of deformities.

Enormous sows must be separated from their young by steel bars to avoid piglet crushing, depriving them of engaging their natural mothering instincts. They also succumb to heart failure.

Dogs previously established as working breeds are kept as pets with fanatical emphasis placed on particular appearance.

There is no logical explanation for the obsession with pedigree only to say that it reveals an extension of the owner’s capacity for discrimination. Dogs are by nature companions to man in their role as ‘man’s best friend’. And yet people who call themselves animal lovers strive to maintain peculiar attributes in certain breeds based on form, which clearly cause suffering. The bulldog is an example where almost every system is compromised: The legs are deformed, restricting normal exercise behaviour; eyelids malfunction causing dry eye and corneal ulceration; compressed facial features impair breathing and create skin folds susceptible to infection; they cannot mate or give birth naturally.

Other breeds like the dachund has a strong likelihood of intervertebral disc prolapse resulting in extreme pain, for the sake of a long back and stunted legs. Bull terrieirs often suffer a lifetime of debilitating skin disease. Nearly all Cavalier Spaniels have a degree of heart failure. Many poodles will develop retinal atrophy leading to blindness. Crippling hip dysplasia is prevalent in Labradors and German Shepherds. Bone tumours and weak hearts shorten the lives of Great Danes. For every breed there is a list of potential problems both physical and mental that have been created while reducing the gene pool and favouring genetic mutations.

The only solution is to celebrate diversity and embrace the strengths revealed through hybrid vigor. Cross breeds are unique, tough, disease resistant, and exhibit the normal behavioural traits of the species. It is clear that our heritage of indigenous breeds like Nguni cattle, Windsnyer pigs, and Africanis dogs excelled through natural selection into healthy living examples of how nature, perhaps unscientifically, ensures reigning of the fittest.