Dogs often bang into each other and suffer minor injuries during vigorous play. They tear ligaments, stretch muscles, get bruises, and even break bones, just like people do. A dog who is lame will try to get the weight off the painful leg by reducing the amount of time she spends on that leg. To accomplish this, she will raise her head and/or alter her gait.

Don't wait several days after an injury to see a vet, however, because your dog may begin to use the leg again despite significant damage to bones, ligaments, or muscles. Months or years later your dog may develop chronic arthritis as a result of the injury, which should have been surgically repaired when it first happened.