Research is intensifying on the subject of cancer in purebred dogs. Pure breeds often have a family line that is well tracked to deliver desirable traits of the breed, unlike mixed breeds or mutts. This means there is a record of genetic information scientists can study, which is uncommon in dogs that are not pure bred. Based on existing research, the lifespan for mutts is approximately 10% longer than purebred dogs, and there may be a few reasons why.
Smaller Gene Pool
Dogs who are registered purebred have a smaller pool of genes in their ancestral line. Often, their parents/ancestors have to be registered as well and there should be a history of health reports available. The pool of purebred dogs is small and breeders often select those with the most desirable traits, making the pool of options even smaller. Additionally, some organizations including the American and U.K. Kennel Club, closed off the breeding book a long time ago, so the purebreds now are from existing dogs. Many pure breeds are inbred due to the decrease of different ancestral lines and desire for specific traits, and specific genes related to that desired trait become more prevalent with each generation. Therefore, if one dog four generations before yours had cancer, your dog probably has a higher chance of developing cancer solely due to genetics.
Time Period for Breeding
Cancer usually develops later in life for dogs, as is the case for humans. A dog will have probably already had puppies by the time they show signs and develop cancer, meaning the gene will have already been passed down to the next generation. To add to that, dogs with desirable looks such as show dogs, will likely have been bred many times to produce a lot of offspring with the same genetic qualities. At that point, by the time the parent dog does develop cancer, its genes will have been passed on to numerous other dogs.
Gene Varieties by Coat Color
Sometimes a specific color of a breed is more likely to develop cancer than other colors. Coat color is determined by their genes and a specific gene called KITLG may be responsible for certain diseases. For example, black Standard Poodles have higher incidences of nail bed squamous cell carcinoma than their lighter color relatives. They have abnormal copies of the KITLG gene and while lighter coats may also have abnormal numbers, they seem to have a mutation that prevents the squamous cell carcinoma. This pattern has also been shown in Briards and Giant schnauzers.
What Can You Do?
It is possible for any breed of dog to develop cancer. You can talk with the breeder and ask what they are doing to address health concerns and higher incidences of cancer in pure breeds. Educate yourself on the breed before you adopt, but responsible breeders should know the ins and outs of the health patterns in whichever breed they are working with. Ask the breeder for health records of the dog’s parents. They should have performed an examination of joints, eyes, heart, hips, and thyroid before breeding.
When you do bring a dog home, it is important to establish and maintain an open conversation with your veterinarian. Schedule annual checkups and be aware of the early signs of cancer. The research in dog cancer is still relatively new and institutions are continuously learning more, so this is promising for the future of dog cancer treatment and prediction.