Judging from all the dogs strolling with their owners at the Harrison Festival of the Arts this weekend, folks are pretty devoted to ensuring their pets’ long, healthy lives. Generally, there is a guideline as to which breeds are at risk for certain diseases. But now there’s a new study that provides a rare and comprehensive look at the causes of death in more than 80 breeds.
The study, which was recently published in the Journal of Veterinary Internal Medicine, is bound to be helpful in developing breed-specific maintenance programs.
“If we can anticipate better how things can go wrong for dogs, we can manage their wellness to keep them as healthy as possible,” said study co-author Dr. Kate Creevy, assistant professor with the University of Georgia, College of Veterinary Medicine.
Creevy and her colleagues looked at data from the Veterinary Database to find the causes of death of nearly 75,000 dogs spanning 82 breeds over a 20-year period from 1984 to 2004. They classified the deaths by organ systems and disease processes and analyzed the data by breed, age and body mass.
“The study was the idea of my collaborator, Daniel Promislow, who is a geneticist,” said Creevy. “He studies aging in a variety of species and became intrigued with the fact that large mammals live longer than small mammals but that situation is reversed among dog breeds. He became curious as to why that might be and whether finding differences in the causes of death based on the sizes of dogs might yield information that applies not only to dogs but also to people.”
Scientists first mapped the dog genome in 2003 and have since compiled data on genetic variations for over 80 breeds. By combining that data with the study material, they could search for genes that influence the risks of diseases.
Some of their findings surprised them. Toy breeds such as Chihuahuas and Maltese are known to have high rates of cardiovascular disease (19 and 21 per cent of breed deaths respectively), but they found that fox terriers also have high rates of cardiovascular disease at 16 per cent.
Golden retrievers and boxers are known to have high rates of cancer (50 and 44 per cent of deaths respectively) but they found that the Bouvier des Flandres actually has a higher death rate from cancer at 47 per cent than the boxer.
They found that larger breeds are more likely to die of musculoskeletal disease, gastrointestinal disease and, most notably, cancer. Smaller breeds had higher death rates from endocrine causes. But breeding for certain traits may also increase the risk of disease.
For instance, short noses in bulldogs could increase the risk of upper respiratory diseases because of the altered airflow. Respiratory disease, though, was also the most common cause of death for Afghan hounds and the Vizsla, which couldn’t be explained.
“Sometimes the cause of death may be related to how we use dogs more than their genetic background,” Creevy said. “Treeing walker coonhounds have a high proportion of deaths from infection.”
Coonhounds are woodland hunting dogs in the U.S. southeast. The question becomes do these dogs have genetically poor immune systems or are they are higher risk because of the kind of environment they are exposed to?
The study intriguingly raised more questions than it answered and their research continues in the search to understand breed-based genetic differences.
“(We will be) looking at individual breeds and individual diseases,” said Creevy. “It is at this level that the work will become the most valuable to dog breeders and owners.”
Learning about canine disease genetics could also help develop new strategies for diagnosis and treatment for human health.
