Although most dogs love to run and play outdoors, often they're slowed down by knee problems. A dog's knee, which is known as the stifle, is similar to the human knee. The cranial cruciate ligament (which is the anterior cruciate ligament or ACL in humans) is the ligament that's torn most in dogs, resulting in lameness, pain and joint instability. Whenever you notice your pet showing symptoms such as limping or hopping, it's important to take him to the veterinarian to determine the extent and nature of injury.
Cruciate Ligament Ruptures
Large, overweight dogs are more prone to develop cruciate ligament ruptures. This is because of the tibia slope of a dog's knee. Often cruciate ligament ruptures cause cuts and tears in the meniscus or cushion. Also, dogs who have received corticosteroid medications have a greater chance for this condition. Dogs with this knee rupture should be X-rayed to see if surgery is needed. If untreated, it might improve over a week or two, but the knee will be swollen, and arthritis may set in quickly.
Medial Meniscus Tears
Medial meniscus tears are another common canine knee problem. The menisci are pads between joint bones. Besides helping joint stability, the menisci have other jobs such as shock absorption and lubricating cartilage. Usually, they suffer damage when a ligament is injured, increasing the chance for more damage because of the stifle's instability. All stressful activities, such as running and jumping, should be reduced or stopped. Owners should follow the vet's advice on providing the right conditions to help the stifle restabilize and heal.
Torn Knee Ligaments
Breeds most prone to torn knee ligaments are cocker spaniels and Rottweilers because of their build and genetic predisposition. Although ligaments in dogs are strong tissues, when injured they tend to heal slowly or incompletely. Leaping to catch a ball or frisbee can cause ligament damage gradually. Symptoms may include some lameness, which seems to improve in a few days or weeks. A partial tear causes knee joint inflammation, with the already weakened ligament undergoing more damage by continual weight-bearing when walking.
Dislocated Knee Cap
Smaller dogs suffer from kneecap dislocation more often than larger breeds. In some smaller breeds, the groove in the lower leg bone (tibia) becomes thickened with ageing, causing the patella to slip out of place. A common symptom is hopping instead of putting the leg down, because it has locked up and can't be straightened.
Middle-aged dogs of smaller breeds, such as Pomeranians and poodles, as well as miniature and toy breeds, are at risk for a luxated patella. Breeds with short legs, such as dachshunds and basset hounds, are also susceptible. The condition is caused in some dogs because of trauma or malformation. When the ridges that form the patellar groove aren't prominent, it creates a shallow groove. This results in the patella jumping out of the groove sideways, particularly toward the inside, causing the leg to lock. Dogs suffering from luxated patella may hold up a leg following the first incident.
Trick Knee Cap
The condition known as trick kneecap (patellar luxation) is caused by misaligned knees. Most common in toy breeds, trick kneecap usually involves one leg that's in worse condition than the other, although both sides may be affected. This problem starts early in a dog's life while bones are growing. In severe cases, both bone shapes can be distorted, causing muscle groups to shift positions.