Bone Cancer in Dogs

Chondrosarcoma is the second most common type of bone tumor found in dogs, following osteosarcoma. It can affect dogs of all ages, but is most commonly found in older dogs. Larger breeds of dogs are more susceptible to chondrosarcoma, Boxers and German Shepherds having the highest occurrence. Chondrosarcoma can be life threatening, and the rate of survival negatively correlates with the cancer’s progression upon diagnosis.

Chondrosarcoma is a malignant form of bone cancer in dogs characterized by a tumor of neoplastic chondroid and fibrillar matrix forming in cartilage. Chondrosarcomas often develop in the ribs, nasal cavity and pelvis but can metastize, or spread to extraskeletal sites such as the mammary gland, heart, aorta, larynx, trachea, vertebrae and penis.

Symptoms vary depending on the site of the tumors and whether they have metastasized, or begun to spread to other parts of the body. Common symptoms include:

• Limping or lameness (most often the first to manifest)
• Localized swelling
• Localized pain
• Sneezing and difficulty breathing
• Nasal discharge and/or nosebleeds
• Bone fracture
• Weight loss
• Increased blood calcium levels

To aid the veterinarian in diagnosis, bring your dog in for an examination as soon as you recognize symptoms. Be sure to fully report the nature, onset and progression of your dog’s symptoms. The veterinarian will begin by performing a thorough physical and orthopedic examination of your dog’s hips, legs, shoulders, spine, joints and bones to check for abnormalities. This will be followed by a complete blood count, a biochemistry profile and a urinalysis. The results of these tests will be used solely to discover if you dog has any other health issues that may be causing the symptoms or need to be considered during treatment; if your dog has chondrosarcoma, all results will be within the normal range.

The veterinarian will take tissue samples from lymph nodes in order to analyze for cancerous cells. If nasal chondrosarcoma is suspected, a nasal bacterial culture will be taken and analyzed, as well as a rhinoscopy, or examination of the nasal passages. Further, a combination of x rays, computed tomography (CT) scans, nuclear bone scans, and radiographic scans will be taken in order for the veterinarian to identify and diagnose the type of tumor and its progression. Since it can be difficult to distinguish between osteosarcoma, chondrosarcoma and sarcoma in imaging, the best tool for diagnosis will be the biopsy of the cancerous growth for microscopic analysis in the laboratory.

Because chondrosarcoma advances so rapidly, there is only a 10% chance a dog will survive past a year of metastasis. For this reason, getting treatment as soon as possible increases your chance of survival. Be sure to talk with your vet about your dog’s chances of survival and recovery as you will need to make decisions regarding treatment.

If caught before a tumor has metastasized, an operation to remove the tumor or amputate the affected limb will increase your dog’s chances of recovery. In the case of an affected leg, your veterinarian’s physical orthopedic examination of your dog will help determine if there is a chance of living a healthy life with the remaining limbs. If the tumor has metastasized, surgery may still be done, but even if the primary tumor is removed, there is only a 10% chance of survival. Surgery or amputation will likely be an extensive procedure involving a significant period of recovery, and only 2% of dogs are likely to survive two years after surgery.

Radiation therapy and chemotherapy have not proven effective at treating chondrosarcoma, but radiation therapy is still considered an option to prolong life and relieve pain in cases of nasal chondrosarcoma, or in other cases when surgical removal of the tumor is not possible. Anti-inflammatories, pain medication, and sleeping pills may be prescribed to help ease pain, and euthanasia may be considered in cases with poor prognosis and debilitating pain.

If your dog has surgery, limit his activity and provide a comfortable, quiet place to rest during recovery. For some dogs, this may mean confining them to a comfortable crate. Consult your veterinarian regarding a recommendation for your dog to relieve himself. Also consult your veterinarian on food intake during recovery. It is important for recovery that your dog be getting the right amount of food. In a case where your dog cannot eat on her own, you will be advised on how to properly use a feeding tube. Carefully follow your veterinarian’s after care instructions, particularly regards to the site of surgery.

In the case of amputation, follow advice on how and when to reintroduce your pet to activity. Keep in mind that most dogs are able to adapt to the loss of a limb easily.

Your veterinarian will prescribe painkillers to help your pet recover from surgery or to cope with the pain otherwise. Never give your dog a higher dose than prescribed. It’s important to keep track of each time you give your dog a dose of a painkiller in order to avoid overdose.