@drboazman explains that a limping pet = a painful pet & should always be addressed with your vet.
High quality digital x-rays & a consultation with a board certified veterinary radiologist are a component of evaluating potential sources of pain in your pet.
X-ray imaging is non-invasive, easily achieved, & provides invaluable information for you & your pet.
With this information we can often make an accurate diagnosis, understand potential treatment options, & provides a prognosis for your pet.
One of the toughest conditions we see in vet med is cancer. Bone cancer is painful & aggressive & has an affinity for growing within the leg bones of large & giant-breed dogs.
A cure for this disease does not exist & treatment is aimed at pain relief. Surgery is the component treatment for osteosarcoma. The most commonly recommended treatment for osteosarcoma is amputation (surgical removal) of the affected limb.
The question you might then ask is “Why perform such an aggressive surgery, when the result will not be curative?”
The answer is simple. Osteosarcoma is a dreadfully painful disease. The primary goal of therapy is elimination of that pain & to restore a good quality of life. Amputation has the ability to accomplish both of these objectives.
Is amputation the right choice for every patient with osteosarcoma? No it is not !
The elderly who has been a couch potato, because of severe arthritis in multiple joints, is unlikely to adapt well to life as a three-legged dog. However the older who has been a lean, mean, running machine will very likely be back to all of his usual tricks within a couple of weeks following surgery.
Other therapeutic options, other than pain relief, can be provided by a veterinary oncologist who can explore further treatment options with you.