Strains injure tendons that link muscles and bones. This can happen if your dog stretches too far, too much, or too often. Athletic dogs often get strains, but this injury also can happen when any dog slips, falls, or jumps during normal play. Dog strains are common in the hips and thighs.
Sprains harm the ligaments that connect bones, which causes joint damage. Sprains can happen to hunting dogs who jump hurdles, as well as to the average dog who may hurt himself taking a hard landing off the couch, or even by something as simple as stepping in a hole. The wrist and knee are common joints for dogs to sprain. One of the most serious injuries is a torn cranial cruciate ligament (CCL), which connects the bones of the knee.
• Torn Ligaments:
If your dog goes lame in one of his hind legs, he may have torn or ruptured his cranial cruciate ligament, or CCL – similar to the ACL in humans. This ligament connects the back of the femur (the bone above the knee) with the front of the tibia (the bone below the knee).