Achy Joints times 4. Arthritis can affect anyone, not just us animals with two legs. Pets, especially dogs, can suffer from arthritis too. Pet arthritis can develop due to many reasons. One of the primary causes is simply age. With age, a pet with joint problems is likely suffering from degenerative joint disease. As with humans, weight can also be the culprit. Heavy dogs are more likely to develop arthritis than small dogs or pets–because there is more strain on their joints.