Osteosarcoma – Bone Cancer in Cats

Picture of a sick cat

Osteosarcoma is one of the most painful and dangerous tumors that can affect cats. Although the incidence of this type of cancer is lower than it is in dogs, it’s still heartbreaking since it can metastasize to different parts of a cat’s skeleton.

In today’s article, we’re looking at several important facts about bone cancer in cats — its symptoms, diagnosis, treatment, and recovery.

What Causes Bone Cancer?

Unfortunately, the causes of bone cancer or any other type, for that matter, are unclear. Some cats can be genetically predisposed to the disease as their parents or grandparents might also have suffered from a form of bone cancer.

Others can develop it as a result of being consistently exposed to carcinogenic substances, whether from cleaning products, cat food, or other sources.

There are also oncogenic viruses involved in the process, so cats can transmit cancer to one another through bites, for example. For this reason, indoor cats are typically less exposed to disease, in general, and cancer, in particular, if they don’t go outside at all.

Different Types of Bone Cancer

We mentioned osteosarcoma at the beginning of the article because it is perhaps one of the most dangerous forms of bone cancer, but there are several other types that cats can develop.

Cats can have bone cysts, non-cancerous bone tumors (very rare), benign neoplasms such as osteofibroma or osteoma (in younger animals), joint tumors like sarcoma, and finally, osteosarcoma.

Unfortunately, osteosarcoma is the most common cancer type that cats can develop. But even taking this into consideration, you should know that osteosarcoma affects around 5 cats out of every 100.000 ones. Unfortunately, it also makes up for more than seventy percent of all bone tumors that cats can develop.

Although there isn’t a specific age that’s more likely to develop this type of cancer, the average one where cats are diagnosed with osteosarcoma is 10. This means that they are slightly older compared to dogs — at least when they’re diagnosed with bone cancer.

Symptoms of Bone Cancer in Cats

Here are some of the clinical signs that are noticeable in a cat with bone cancer:

  • Lameness in one or several of the cat’s limbs
  • Bone inflammation which can subside and then reappear in another location
  • Weight loss
  • Local or general pain
  • Weakness or lethargy
  • Loss of appetite
  • Neurologic symptoms in cats that have vertebral tumors or in the skull
  • Breathing difficulties for cats that have rib tumors

Cats that have developed neoplasia in their jaw may show other additional signs, such as excessive salivation, difficulty eating or drinking, or inflammation in their jaw.

Many cats will show a reluctance to play, although it might be uncharacteristic for them. If you notice any of these symptoms in your cat, contact your veterinarian and take your pet to the animal hospital as soon as possible.

How Is Bone Cancer in Cats Diagnosed?

Besides a clinical examination, the vet will use a variety of tests to discover whether your cat is indeed suffering from bone cancer or not. This could mean a blood test, urine samples, along with special methods of examination like imaging diagnostic techniques such as an x-ray.

CT is usually more effective in determining the location and size of the tumor, as well as which bones are affected and the depth to which the neoplasm has penetrated the bone structure.

Fine needle aspiration can also be used as a special diagnostic method, and it might reveal the type of cancer that the cat has developed. In other instances, a biopsy might have to be performed, and the cat will go under sedation so that a piece of the tissue is collected and examined.

The purpose of all of these tests is to establish the type of cancer, its malignancy, and the stage it has reached.

Therapy Options

Most bone cancers are treated with medication, radiation therapy, or surgery. Depending on how aggressive the type of tumor the cat has developed is, your vet will recommend one or several different types of treatment.

A veterinary oncologist will also be involved, and along with the pet owner and their clinical vet, they will choose the right therapy.

Chemotherapy is typically used alongside surgery as otherwise, it might not lead to a significant extension of the animal’s survival time.

On the other hand, depending on the location of the tumor, an operation might not be possible. Rib tumors, for example, might not be operated on. Limb tumors are generally treated with both chemotherapy and surgery, and sometimes, the limb might have to be amputated altogether, especially if the diagnosis attests that the tumor hasn’t spread to other parts of the cat’s body and is in one of its incipient stages.

Depending on the cancer type and the therapy used for treating it, cats have various survival times. Osteosarcoma is, unfortunately, one of the most aggressive types of feline bone cancer, and it is also associated with the lowest survival times.

Cats that have osteosarcoma and are treated with chemotherapy and surgery can have a survival time that can extend to 3-4 years. For chondrosarcoma, fibrosarcoma, or grade 1 or 2 synovial cell sarcoma, the survival time is better, and they might also be treated with surgery alone.

If there is anything positive about feline bone cancer, it’s that it doesn’t tend to metastasize as frequently as it does in other animal species. For this reason, limb amputation and chemotherapy can lead to a positive prognosis.



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