Since then humans selectively bred for dogs that could help them as herders, guardians, hunters, draft animals and companions. Dog breeds were created that could help with virtually every human activity. Many of our breeds can be traced back thousands of years. However, the vast majority of today’s modern breeds were created in the last 100-200 years.
Humans created dog breeds by selecting for genetic qualities in dogs that they valued. But they also unknowingly selected for nearby genes that carried disease causing mutations. In this way they inadvertently increased the frequency of deleterious mutant genes in the breed.
Many of our modern breeds were started from a relatively small population of founders. For example, the Bernese Mountain Dog breed was founded in 1907 from a small group of approximately 50 farm dogs in Switzerland.
If there were genetic mutations present in founder dogs then those mutant genes will be present in their descendants today. Most of these mutant genes are what is known as recessive. That means if only one mutant copy of the gene is present in a dog then that dog will not display disease symptoms. However, when a dog carries two copies of the mutant gene, then that dog is at risk for disease symptoms. It is easy to see how recessive mutations could stay “hidden” in each breed over many generations. They are hidden, until two carrier dogs are mated and some of their puppies inherit two mutant copies and then exhibit symptoms of the disease.
The best and easiest way to know if your dog is a carrier of a genetic disease, or if your dog has two mutant copies of the gene and is at risk of suffering from disease symptoms, is to perform DNA-based genetic testing.
San Bruno Pet Hospital now offers testing for over 150 genetic diseases, as well as coat color and coat trait testing. These tests are available for your purebred or mixed breed dog. All DNA testing is done from a simple, non-invasive cheek swab or a blood sample. Come on in or give us a call to discuss if this service makes sense for your dog.
In future articles we will talk about specific breeds and the genetic diseases that afflict them. Next month, genetic testing in Bernese Mountain Dogs.