Dogs can do fairly well on three legs if need be, though it takes them a while to adjust

 Dogs can do fairly well on three legs if need be, though it takes them a while to adjust. So if, for instance, the vet put your dog's leg in a cast because it was broken, you'd probably see her managing some exercise fairly well once she figures out how to modify her gait. She almost certainly does need a bit of exercise, otherwise, her joints will become stiff. Try her on short walks, preferably on grass. She will signal you when she's had enough. But please do get her injured leg seen by a vet. A vet can help with pain relief, which may be what is causing her not to want exercise.

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