This is one question that you definitely should talk to your veterinarian about. However, in most cases, a healthy dog can carry about 10 to 15% of its own body weight. So a dog that weighs 50 lbs should be able to carry about 5 to 7.5 pounds of extra weight without too much of a problem. It is important to remember, though, that each dog is different and does after different abilities. So be sure to check with your vet to get a more accurate determination of the weight your dog should be able to handle.