Clinical Applications of Genetic Testing

Our understanding of genetics has advanced at a remarkable pace in the last few years, and as a result the options for genetic testing are increasing dramatically. Benefits are already starting to become apparent for the veterinarian, as Jamie Freyer and Angela Hughes describe in their overview of the current situation.

Introduction

The field of genetics has progressed far beyond most people’s recollections of Darwin’s Galapagos finches and Mendel’s wrinkled peas. In fact, there has been exponential growth in this area within the last few years alone. Most major animal species have had their genomes sequenced, including the human, dog, cat, horse, pig, cow, and mouse. With the new tools available, scientists have learned a tremendous amount about how traits and diseases occur and are inherited.

This knowledge is changing the way that we, as veterinarians, approach our patients. For example, it was only a few decades ago that a serious side effect of ivermectin was identified in some Collies (1) (see page 14). It is now known that the molecular cause is a small deletion in the multi- drug resistance gene which can eliminate the function of a vital drug-transport pump in the blood-brain barrier (2), and it is now evident that this mutation is not only present in many pure- and mixed-breed dogs other than the Collie, but that it involves many drugs beyond ivermectin (3). Such knowledge makes us better clinicians and leads to better care of our patients.

Understanding and utilizing these genetic advances enables clinicians to provide comprehensive care for patients and increase client awareness of the value of that care. We can provide individual care plans for our patients by tailoring our approach not only to our patient’s life stage, but also to their breed. Identifying breed-specific risks and customizing a patient’s care based on their breed background improves the client’s relationship with the veterinary practice and allows for more rapid diagnosis and earlier medical intervention.

Most veterinarians probably already take some breed differences into account when making medical decisions or speaking with owners, but it is important to develop a consistent message that the entire team can relay for each breed. This should be discussed with clients at an early point in any treatment so that they can be prepared, and the best possible wellness plan can be created for their pet. Well-informed owners are more likely to visit the clinic for routine care more often, perform the recommended preventative care, and recognize when pets are ill sooner.

Obviously, this type of breed-specific healthcare is easily applied to the portion of patients that are purebred dogs or pedigree cats, but now this benefit can be extended to mixed-breed canine, and increasingly feline, patients as well. DNA testing to evaluate the purebred ancestors within the recent lineage of a mixed-breed dog has been available for a decade now and the technology is constantly improving. Based on this information, veterinarians can help clients better understand their dog and create an individualized wellness plan for them. In this day and age it is a medical imperative to understand each patient’s breed history and treat them appropriately. [...]