Breeding Away from Epilepsy in the Belgian Tervuren

Understanding the genetic mutations that underlie a disease has many benefits. It may lead to the development of more accurate diagnostic tests or point to new ways to treat the disease. For dog breeders, identifying these mutations is one part of maintaining the health of their breed. The goal is to test breeding stock for mutations that confer an increased risk of harmful conditions relevant to their breed. Knowing the genetic status of breeding stock allows breeders to choose mating pairs that are less likely to produce puppies affected by certain diseases. Over time, this careful selection helps reduce the total number of dogs affected by the disease(s) in question as breeders gradually ‘breed away from’ them.

Please note: the goal should not be to eliminate all disease-causing mutations, as important and helpful genes may be removed with them. Instead, the goal is to manage mutations to minimize the number of dogs clinically affected by relevant conditions.

This may sound easy, but it quickly becomes complicated when evaluating a breeding pair for the presence of risk mutations for two, three, four, or more relevant conditions. This is why transparency of health testing results and a proactive, long-term breeding plan are essential for improving the health of any breed.

The AKC Canine Health Foundation (CHF) has funded many studies exploring the genetic causes of canine disease. For example, CHF-funded investigators at the University of California, Davis explored several mutations associated with idiopathic epilepsy in the Belgian Sheepdog and Belgian Tervuren (CHF Grant 02936: Validating Genetic Variants Underlying Canine Idiopathic Epilepsy and Exploring Their Functional Roles in the Belgian Sheepdog and Tervuren). They confirmed the presence of mutations on chromosomes 37 and 14 which increase the risk for epilepsy in these breeds.

With this knowledge, have Belgian Tervuren breeders been able to breed away from epilepsy? Principal Investigator Dr. Anita Oberbauer followed up on her research to determine if the prevalence of idiopathic epilepsy in this breed has decreased over time. Comparing the frequency of epilepsy risk mutations in Belgian Tervurens born 1985-1999 to those born 2000-2015 yielded interesting results. There was no significant change in the frequency of these two risk mutations combined. Similarly, the frequency of the chromosome 14 risk mutation remained unchanged. However, the chromosome 37 risk mutation frequency decreased in epileptic dogs but increased in healthy dogs. Surprisingly, despite breeder efforts, the current prevalence of idiopathic epilepsy in Belgian Tervurens is higher than it was decades ago - calculated at 27.1%, compared to the 18% prevalence reported from an owner survey in the 1980’s.

Prevalence: the number of cases of a disease in a specific population at a particular timepoint or over a specified period of time.

Given the increased awareness of epilepsy and its genetic risk factors, why is epilepsy more common in the Belgian Tervuren now than it was before? There are several potential reasons for this disappointing trend.

• Environmental factors such as stress, weather, and more can trigger seizures. Have these environmental factors become more frequent over time? How do genetic and environmental factors interact to trigger seizures in dogs?

• Additional genetic risk mutations may have developed over time. Breeding away from the two risk mutations studied here may not be enough to prevent dogs from developing epilepsy.

 
This study highlights the complexity of fighting disease in dogs. Ongoing research is needed to understand disease-causing mutations and their effects. Dog breeders, dog owners, and veterinary professionals must remain informed and proactive, relying on scientific evidence to guide their decisions. CHF and its donors remain committed to funding studies that seek to answer these challenging questions and advance the health of all dogs. Learn more about the Foundation’s commitment to understanding canine epilepsy at www.akcchf.org/epilepsy.