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Breeding for appearance might produce pretty looking pets, but the consequences can be great, as Blue Cross chief vet Caroline Reay reveals… 

Anyone who has ever tried to run for a bus in high heels knows the risks of looking good. And our desire for “good looking” pets can cause them problems too. 

The disadvantages of a short nose, prominent eyes or bandy little legs are obvious, but there can be hidden costs too. 

Selective breeding for appearance can have unintended consequences which are more than skin deep. 

Genetic problems in pets 

A gene is a blueprint for the manufacture of the different proteins that make up the body. As researchers unravel the mysteries of the dog genome, they have found mutations (errors which arise when the blueprint is copied during growth) which cause particular diseases. 

But it’s complex; there can be more than one error causing a particular problem and parts of the blueprint not apparently used may have effects. There may be an environmental influence too. 

Scientists have found genes that make some breeds of dog vulnerable to particular types of cancer. Breed vulnerability isn’t a surprise, but what is new is that typing the genes involved can predict which cancers will respond to chemotherapy drugs. These findings, from studies in dogs, will benefit people too. 

Gene mutations in dogs can cause allergies and some anaemias, whilst in cats a group of gene mutations has been identified which are linked with heart disease. 

Genetic conditions seem to be more common in pets than in people. In humans genetic conditions affecting one in 500 people are considered “common”. 

Surveys in dogs suggest that between 1 and 10 of every 100 dogs is affected, and the true incidence is probably higher. 

The desire for a perfect pet 

It’s because the human desire for the “correct” appearance in dogs has been heavily pursued, with breeding from a small number of apparently “perfect” dogs. 

In reality some had genetic errors which have now spread through the population. One male can pass a genetic mutation on to an awful lot of puppies. 

Sadly, cat breeders may be following the same route as the demand for “different” cats fuels the development of types like the Munchkin.  

Yet looks are not important to animals. What matters to them is to be able to run and play and to breathe and see effortlessly. 

Is it too late to turn back the clock? There are now more genetic tests available to identify affected animals before they are bred. 

And there’s some limited potential for gene therapy to counteract the effects of malfunction. There may be nothing wrong with planned breeding, but perhaps it’s time to start breeding for pets to be companions rather than household ornaments or fashion accessories. 

There are lots of advantages to taking on a rescue pet over buying a puppy or kitten privately – if you’d like to find out more, please visit our rehoming pages.