Core strength could help dogs avoid knee injuries

That knee injury is a cranial cruciate ligament rupture, which is equivalent to an anterior cruciate ligament (ACL) tear in humans.

According to a research survey documenting activity and injury odds of more than 1,200 agility dogs, just about any physical exercise seems to lower the risk of rupturing the ligament, but some exercises seem to increase the risk. In addition, the size and shape of the dog -- and thereby certain breeds -- were also found to be at higher risk.

"Balance exercises, wobble boards, anything that improves the core strength of the dog seemed to lower the odds of a ligament tear," said Deb Sellon, a Washington State University veterinarian and lead author on the study published in BMC Veterinary Research. "We found fitness matters for dogs just like it does for people, and we haven't shown that before."

Sellon is also the founder of the university's Agility Dog Health Network, which was accessed in the study. By using odds ratios, which is essentially a statistical risk assessment, Sellon and Denis Marcellin-Little, a veterinary orthopedic specialist with University of California, Davis, looked for trends in 1,262 agility dogs -- 260 that tore the ligament and 1,002 dogs that did not.

In addition to balance and core strengthening exercises activities like dock diving, barn hunt and scent work are associated with a decreased rate of ligament rupture, too.

While regular activity, like swimming, playing fetch or frisbee, walking or running didn't increase the risk of injury, it didn't lower the odds either.

Surprisingly, dogs that competed more frequently in agility events and competed at a higher level on more technically rigorous types of courses were less likely to rupture their cruciate ligaments.

The only physical activities that increased the odds of injury were short walks or runs over hilly or flat terrain on a weekly basis, and many of those injuries were in dogs early in their agility career that lacked core strength from routine physical exercise or at times, rest days.

Training or competing in the new and popular dog sport flyball was found to be the riskiest activity of all activities evaluated in the survey. Agility dogs that also engaged in the sport of flyball were nearly twice as likely to rupture the ligament as compared to other dogs. Nearly 12% of dogs reported to play flyball ruptured the ligament.

The survey confirmed some long-standing and well-accepted risk factors as well. In particular, female dogs spayed before the age of one were almost twice as likely to rupture the ligament compared to dogs that were spayed after their first birthday. Sellon said this is believed to reflect the importance of hormones in developing strong ligaments in young animals.

Trends were also identified among certain breeds.

Survey results indicated Australian shepherds and Labrador retrievers were more than twice as likely to rupture the ligament. Rottweilers and Australian cattle dogs were more than four times as likely to tear the ligament.

Marcellin-Little speculates that could have something to do with the shape of the dog, and maybe its tail.

"Larger dogs doing agility tend to be less balanced, so it is not surprising a Rottweiler or Australian Shepherd may be at a higher risk of a rupture compared to smaller breeds," he said. "The tail could also be a factor; the tail has been proven very important for cheetahs and you can imagine it has a role to play in the overall balance of the dog."

Marcellin-Little said there is still a great deal of research that needs to be completed, but the survey gives veterinarians a place to start.

"This research decreases uncertainty; it doesn't bring certainty, but this one study could provoke thoughts and help us look at potential research areas to target moving forward," he said. "That is the type of research that the Agility Dog Health Network is planning to support."