Diagnosis and Tretment of Osteosarcoma and Other Bone Tumors in Dogs

CLINICAL SIGNS ASSOCIATED WITH BONE AND JOINT TUMORS Appendicular tumors most commonly are associated with lameness. It usually is chronic and progressive, but occasionally dogs can present acutely with severe lameness associated with pathologic fracture. A firm to hard swelling might or might not be palpable, but pain usually is elicited on palpation of the affected site of the bone. Most dogs are otherwise clinically healthy (BAR, good energy level, good appetite, etc.) Axial tumors can present with a variety of signs depending on the affected site. Pain is not always as obvious because these tumors do not involve weight-bearing bones, but usually these tumors still are painful on palpation. Dogs with vertebral tumors can present with pain, weakness, ataxia/proprioceptive deficits, paresis/paralysis. Oral tumors can present with a visible and/or palpable mass, halitosis, dysphagia, anorexia, weight loss, bloody discharge from the mouth, pain upon opening the mouth, and/or exophthalmos. Nasal tumors commonly are associated with unilateral or bilateral epistaxis or bloody/mucopurulent nasal discharge, sneezing, stertorous breathing, facial deformity, and/or exophthalmos Rib tumors commonly are associated with a palpable mass. Very advanced tumors can cause respiratory distress/dyspnea. Thoracic limb lameness also can be seen secondary to mechanical obstruction and/or brachial plexus involvement. Polyostotic lesions (lesions involving multiple bones) can be associated with a variety of signs depending on the sites affected. Some dogs will present with generalized pain that cannot be localized on physical examination. However, if one or a few lesions are significantly more painful than the others, the dog might present with signs referable to only a small subset of the total number of lesions present. Many of the tumors that affect bone can metastasize to a wide variety of locations outside of the skeletal system. Clinical signs associated with disseminated disease often are vague and nonspecific: lethargy, anorexia, etc. Dogs with pulmonary metastasis might exhibit a cough. Overt respiratory distress is less common, and typically only associated with advanced end-stage disease. Hypertrophic osteopathy and secondary lameness can be seen in dogs with pulmonary metastasis. A variety of other clinical signs can be seen depending on the site(s) of metastasis.