There are two essential stabilizing ligaments that cross over one another inside the knee joint. Instability most commonly occurs from cruciate ligament tears (analogous to ACL injuries in humans) and luxated patellas (dislocated kneecaps).
ACL tears occur more frequently in dogs than in cats. Sometimes tears are due to things like landing “wrong” when running and jumping, but they are also affected by weight and even breed. ACL tears in cats most often occur as a result of jumping from high places, playing or getting a leg caught in something. As with dogs, ACL tears happen more often in cats that are overweight.
Warning signs of ACL injury can include:
CATS: Decreased activity or playfulness
DOGS: Lameness or awkwardness of sitting posture (leg sticking out to the side)
Pay attention to limping! Catching an injury quickly can be crucial to your pet’s recovery!
Cats are often first treated with diet management (if overweight) and exercise restriction for 3-6 weeks. If medical management is not successful, surgery is usually recommended. Dogs often go immediately into surgery, followed by physical therapy because delaying surgery usually causes further inflammation and puts the ACL in the other rear leg at increased risk for rupture.
Keeping pets at a healthy weight to relieve pressure on their joints and hind legs; providing ramps or a series of increasing levels of furniture for cats to get to favorite high places; starting exercise at a slow pace to allow for warm-up of muscles and tendons; and exercising on a regular basis (for dogs, 20 minutes three times a day at a minimum).