Future perfect?

Genetic technology offers us the potential to beat equine disease and boost performance, but how far should we go? Dr Madeleine Campbell MRCVS outlines the ethical issues.

- Dr Madeleine Campbell

THE development of new genetic technologies is simultaneously one of the most scientifically extraordinary and most ethically challenging aspects of modern veterinary medicine.

Over recent years, we have developed the ability not only to test adult horses for genetically heritable traits, but also to screen equine embryos prior to transfer into a mare. With the advent of genetic editing, we stand poised at the beginning of an era in which humans can manipulate the equine genome in ways that can affect both current and future generations of horses.

However, while this offers us wonderful opportunities to improve equine health and welfare, it also opens up some fascinating ethical questions.

The sequencing of the equine genome in 2010 facilitated understanding of how diseases are inherited.

As of last year, 237 equine traits or disorders with a genetic basis had been catalogued by the University of Sydney. This knowledge enables breeders to avoid breeding from animals carrying the genes for diseases, particularly where the method of inheritance is “autosomal recessive” – meaning that horses will show symptoms of this type of disease if they have two copies of the defective gene (one inherited from each parent).

A horse that inherits only one copy of the defective gene will not show signs of the disease. If he is crossed with another horse also carrying one copy, there is a 1:4 chance that the foal will inherit two copies and show symptoms.