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pet cancer awareness month: petplan pet insurance takes a look at bone cancer in dogs and cats

  • Dr. Kim
  • Posted by Dr. Kim Smyth on
    Staff Veterinarian and Pet Health Writer of Petplan


As we continue our month-long series on pet cancer during Pet Cancer Awareness Month, today we will focus on bone cancer. By far, the most common kind of bone cancer in dogs is osteosarcoma, and its diagnosis can be quite devastating. Osteosarcoma is so aggressive and fast-growing that by the time it is diagnosed in the bone, usually it has already spread to the lungs. In addition, osteosarcoma is extremely painful for our furry friends. 

Osteosarcoma occurs most often in middle-aged to elderly dogs, though it can occur in young dogs, cats and commonly in Greyhounds. Any bone of the body can be afflicted, but the majority of tumors affect the bones of the limbs. You may notice intermittent or constant lameness for months before you notice signs of swelling. This is because the tumor starts deep in the bone and becomes progressively more painful as it grows outwards. Over time, external swelling can be seen.

Diagnosis can sometimes be made by doing X-rays, as osteosarcomas can show some characteristic changes in the bone:

  • A lesion in the bone will give it a moth-eaten appearance.
  • Pathologic fractures, or breaks in the bone, are quite common, as the tumor weakens the bone.
  • The tumor does not cross the joint space – in other words, if there is bone affected on both sides of the joint, it is likely not osteosarcoma.

Further diagnosis will be made by performing a biopsy on the affected bone. This is often done by amputating the affected limb first. This may seem rash, but consider this: osteosarcoma is extremely painful for your pet, and removal of the affected limb removes 100% of the pain. The median survival time in a pet with osteosarcoma is four to five months without chemotherapy, regardless of whether amputation is performed or not. Amputation ensures that time will be pain-free.

Treatment of osteosarcoma entails fighting its spread and treating your pet’s pain. Most dogs are euthanized due to pain in the affected limb, which is why amputation is such a good option. Though human amputees face certain social implications, the same is not true for dogs – they don’t care what they look like! Following a short recovery time, three-legged dogs will run, jump and play as if nothing is out of the ordinary.

While amputation can help relieve your pup’s pain, there is still the very high risk that the tumor will spread, or metastasize. Chemotherapy can help hinder metastasis and add to the affected dog’s lifespan. Depending on the type of chemotherapy administered, median survival times are around one year, though some combinations of chemo lead to a two-year survival time in 30% of patients. 

A diagnosis of osteosarcoma is certainly devastating, but there are options! Talk to your veterinarian about treatment and possible referral to a veterinary oncologist. Remember that your pet’s comfort is of utmost importance, and should be your top priority. If limb amputation is not possible, talk to your vet about other pain relief options.

Hopefully your pets never develop cancer, but if you protect your furry family member with pet insurance and they do, Petplan can help with the vet bills for treatment, letting you concentrate on your pet's care.  

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Chris AshtonCo-Founder and Co-CEO of Petplan Pet Insurance
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