What is Osteosarcoma in Cats?

What is Osteosarcoma in Cats?

What is it?

Osteosarcoma is a type of bone cancer that affects cats. It often affects the legs or jawbone. It can be aggressive cancer that spreads quickly to other body parts.

How is it Treated?

Treatment for osteosarcoma in dogs usually involves a combination of chemotherapy and surgery. First, the affected limb may need to be amputated, followed by chemotherapy to kill any remaining cancer cells. Additional treatments, such as radiation therapy or immunotherapy, may also be recommended depending on the severity and stage of cancer.

Breed Predispositions

Siamese and Burmese cats.


Jessie, a dedicated cat owner, always looked forward to her evenings spent cuddling with her beloved feline, Whiskers. However, she recently noticed that Whiskers was limping and appeared to be in pain. Concerned, Jessie took Whiskers to their trusted veterinarian for a thorough examination. The vet ran several tests and discovered that Whiskers had osteosarcoma, a type of bone cancer. Shocked and heartbroken by this news, Jessie knew she had to learn everything she could about this disease to provide Whiskers with the best care possible.

Osteosarcoma in cats is a malignant tumors in the bone that occur most commonly in young adult dogs. They’re rare in cats. However, they tend to be very aggressive when they occur. They account for about 95% of primary bone cancers. Most cases arise in long bones, particularly around the knee joint. Other common sites include the pelvis, ribs, and skull.

Cats usually develop osteosarcomas in the long bones (legs) or pelvis. The tumor grows rapidly and causes pain and lameness. They may spread throughout the body, including the lungs, liver, heart, and brain. Up to 90% of Osteosarcoma spreads to a cat’s lungs. Cats with metastatic disease often die within weeks.

Types of Bone Tumors in Cats

Osteosarcoma is the most common type of bone cancer, accounting for about 40% of cases. Fibrosarcoma and chondrosarcoma are much less common, making up 10% and 5%, respectively. Hemangiosarcoma is the least common, representing just 3% of cases.

Chondrosarcoma Tumors

Chondrosarcoma is a rare type of cancer that affects cartilage tissue. This type of tumor often occurs in older cats and dogs, although it can occasionally occur in younger animals. In humans, chondrosarcomata are sporadic tumors that typically occur in the spine, pelvis, ribs, long bones, skull, or jaw bone. These types of cancers are usually slow growing and don’t spread quickly. However, some cases do metastasize and cause death.

Types of Bone Tumors in Cats

Fibrosarcoma Tumors

A rare type of tumor called fibrosarcoma affects about one out of every 10,000 domestic cats. This type of cancer usually develops in older cats, especially those over 12 months old. Although it occurs most commonly in the appendicular skeleton, it can affect almost any body part, including the head and neck region.

Vaccinations are believed to play a role because some studies have shown that vaccination against the feline leukemia virus (FeLV), another common cause of cancer in cats, increases the risk of developing fibrosarcoma. Other factors include age, breed, diet, lifestyle, genetics, and exposure to toxins.

Hemangiosarcoma Tumors

Hemangiosarcoma is very rare and usually fatal. They are soft tissue sarcomas that develop in blood vessels. There are currently no known causes for hemangiosarcoma. However, veterinarians are still determining precisely what triggers them to grow.

Osteosarcoma Tumors

Cats who develop osteosaromatosis usually experience pain and swelling around one of their legs. This is caused by tumors growing in the bone. These tumors are called “osteosarcomas.” They can occur anywhere in the body, including the jawbone, ribs, pelvis, spine, skull, shoulder blade, arm, leg, tail, and even head.

There is currently no cure for this disease. Treatment options include surgery, chemotherapy, radiation therapy, and biotherapy. However, it is essential to note that there is no guarantee that these treatments will work.

Causes of Osteosarcoma in Cats

The cause of osteosarcoma is not fully understood yet, but several factors may increase the risk of a cat developing osteosarcoma. These include genetics, exposure to certain chemicals or toxins, viral infections and trauma.

Studies have shown that specific medical treatments may be associated with an increased risk of osteosarcoma in cats. These treatments are chemotherapy, radiation therapy and immunotherapy.

It has also been suggested that cats exposed to high x-rays over an extended period could be at higher risk for developing osteosarcoma.

In addition to these risk factors, it’s important to note that some cats have a genetic predisposition to the condition making them more likely to develop osteosarcoma than others.

Due to the many possible causes of osteosarcoma in cats, pet owners need to take any symptoms seriously and consult their veterinarian promptly if they suspect their cat might have this condition since early detection increases treatment options and improves chances for successful outcomes.

Symptoms of Osteosarcoma in Cats

Cats with bone cancers often develop pain, lameness, swelling, weight loss, lethargy, fever, vomiting, diarrhea, depression, lack of appetite, breathing difficulties, coughing up blood, difficulty urinating, and other symptoms before they die, according to the American Veterinary Medical Association. In addition, the tumor may cause bone fractures, spinal cord compression, and paralysis.

Diagnosis of Bone Cancer in Cats

Diagnosis of Bone Cancer in Cats

If you suspect your cat may suffer from this disease, schedule a visit with your veterinarian immediately. Your vet will perform X-rays, blood tests, physical examinations, and possibly a biopsy.

Your vet will use these results to determine whether your cat needs further testing, treatment, or surgery.


When diagnosing osteosarcomas in cats, X-rays are often used to determine any evidence of metastasis (spread) to other body parts. The metastatic disease occurs when cancer cells spread from the original tumor site to another body part.

Blood test

Many vets rely on blood tests to detect the presence of specific proteins associated with feline Osteosarcoma, including alkaline phosphatase, CEA, and PSA. These tests are inexpensive, quick, and simple to administer.

However, there are some drawbacks to relying solely on blood tests to diagnose feline Osteosarcoma.

  1. The results aren’t 100% accurate.
  2. The accuracy depends on the level of protein found in the blood.
  3. The amount of protein detected varies depending on the stage of the disease.
  4. The test’s sensitivity decreases after the onset of symptoms.

In short, blood tests alone won’t accurately identify every case of osteosarcoma; therefore, vets must combine blood tests with additional diagnostic tools to ensure the correct diagnosis.

Physical Examination

Your vet should perform a thorough physical exam, including checking your cat’s gait (walking), posture, weight, appetite, energy level, and overall appearance. Your vet will also examine your cat’s paws, legs, chest, abdomen, mouth, nose, ears, eyes, teeth, neck, spine, tail, genitals, rectum, heart, lungs, liver, spleen, pancreas, kidneys, bladder, stomach, intestines, lymph nodes, thyroid gland, salivary glands, skin, and fur.


Veterinarians perform a biopsy by taking a small tissue sample from the affected area. Then, the piece is sent to a laboratory, where it’s examined under a microscope. If the model contains cancerous cells, your vet will know cancer has progressed beyond its early stages.

Treatment Options for Feline Osteosarcoma


The vet may recommend surgery to remove the tumor and surrounding tissues. This helps to prevent a recurrence. Surgery aims to remove as much cancerous material as possible, including healthy cells. Again, this helps prevent a recurrence.

If the tumor cannot be surgically removed, chemotherapy and radiation therapy may help reduce its growth rate and slow its spread. They are effective treatments for feline Osteosarcoma, but they aren’t curative.


Chemotherapy is often used to reduce tumor growth and shrink tumors. However, chemotherapy drugs often cause nausea, vomiting, diarrhea, hair loss, weight loss, fatigue, and mouth sores.

Cats are often treated with chemotherapy drugs, including methotrexate (an anti-cancer drug), vincristine (a cancer treatment agent), and doxorubicin (another cancer treatment). However, these treatments aren’t effective against most types of feline Osteosarcoma.

Radiation Therapy

Radiation therapy uses high-energy x-rays to kill cells actively dividing (cancerous).

There are two main types of radiation therapy: external beam radiation therapy (EBRT) and brachytherapy. EBRT involves placing radioactive material directly inside the tumor site. Brachytherapy involves implanting small pellets of radioactive material near the tumor site. Both treatments are effective at killing cancer cells. However, there are some side effects associated with each method.

Some pets recover entirely after treatment. Others need additional treatments over several months. 


You can also talk to your veterinarian about immunotherapy. This form of treatment involves injecting your pet with particular proteins called cytokines. These proteins stimulate the immune system to attack tumors.

Cytokines work better against certain kinds of cancer cells than others. For example, some cytokines target specific molecules in cancer cells, causing them to die off—other cytokines cause cancer cells to release substances that attract white blood cells to destroy them.

Some cytokines are injected directly into the bloodstream and travel throughout the body. Others are administered through injections into muscle tissue. The most common side effects include fever, vomiting, diarrhea, and loss of appetite.


Amputation is usually recommended when there is no other treatment option available. This is because cats who undergo surgery tend to recuperate very fast. However, it is essential to note that amputation does not always mean immediate death. In some cases, the cat may survive even without limbs.

Prevention of Feline Bone Cancer

Cats with osteosarcomas may present with lameness, pain, swelling, fever, and weight loss. Diagnosis is based on physical examination, radiographs, and biopsy. Treatment involves surgical removal of the affected limb, followed by chemotherapy.

Prevention is key. Contact your veterinarian immediately if you notice changes in your cat’s gait.

  • Vaccinate Your Cat Against Feline Leukemia Virus

Feline leukemia virus (FeLV) is a common cause of lymphoma and leukemia in domestic cats. This virus is transmitted via saliva and urine.

Vaccination against FeLV has decreased the incidence of feline leukemia in cats. Currently, three vaccines are available for cats: the recombinant vaccine, the modified live vaccine, and the killed vaccine.

Recombinant vaccines contain viral proteins produced in cell culture instead of using whole viruses. Modified live vaccines contain attenuated strains of the virus. Killed vaccines contain dead viruses.

All three vaccines protect against the significant subtypes of FeLV. Recombinant vaccines are recommended for kittens under eight weeks old. Modified live vaccines should be used for kittens over eight weeks old. Kittens vaccinated with killed vaccines should receive booster shots every six months until they reach 12 months of age.

Killed vaccines should be administered annually after that.

  • Provide Safe Outdoor Play Areas

Outdoor play areas provide opportunities for cats to exercise and socialize. As a result, playing outdoors are less prone to developing arthritis in cats later in life.

Ensure that outdoor play areas that outdoor play areas are safe for your cat. For example, make that fences are tall enough to prevent your cat from jumping over them. Also, cover holes in the ground with wood chips or gravel to avoid injury.

  • Limit Exposure to Chemicals

Chemical exposure can lead to health problems such as respiratory issues and skin irritation. Common chemicals in household cleaners include ammonia, chlorine bleach, formaldehyde, lye, methylene chloride, phenol, trichloroethylene, and xylene.

Avoid cleaning products containing these chemicals. Instead, use natural alternatives such as baking soda, vinegar, lemon juice, hydrogen peroxide, and borax. Also, be careful about using harsh detergents. These can irritate your cat’s sensitive skin.

  • Avoid Excessive Heat

Heatstroke occurs when your cat’s core temperature rises above 104 degrees Fahrenheit. Symptoms of heatstroke include excessive panting, vomiting, diarrhea, seizures, collapse, coma, and death.

Keep your cat indoors during scorching weather. Provide plenty of fresh water and shade. Do not leave your cat alone in a car during extreme temperatures.

  • Monitor Your Cat’s Diet

A balanced diet provides essential nutrients needed for proper growth and development. Feeding your cat a well-balanced diet will ensure he stays healthy and active.

Feeding commercial diets can be expensive. Instead, try feeding homemade diets made with wholesome ingredients. Also, consider supplementing your cat’s diet with vitamins and minerals.

Be aware of what foods are toxic to your cat. For example, the raw liver can cause severe gastrointestinal upset.

  • Get Regular Checkups

Regular veterinary visits are necessary to monitor your cat’s overall health. During annual exams, your vet will perform a thorough physical exam, test your cat for diseases, and administer vaccinations.

During regular exams, your vet will examine your cat’s eyes, ears, teeth, mouth, nose, throat, abdomen, genitals, and tail. He will also measure your cat’s height, weight, and head circumference.

  • Control Fleas

Fleas are external parasites that feed off of your cat’s blood. They can transmit tapeworms and roundworms. Fleas can also spread bacteria that cause ear infections, eye infections, pneumonia, urinary tract infections, and dermatitis.

Regularly apply insecticide to your cat’s bedding and furniture to control fleas. Use a flea comb to remove fleas from your cat’s fur.

  • Maintain Good Hygiene

Keeping your cat clean helps him stay healthy. Brush his coat daily to remove loose hair and dirt. Clean his face, paws, and nails weekly.

Bathe your cat once a month. Rinse his coat thoroughly before drying.

  • Watch Out for Scratching Post Syndrome

Scratching post syndrome is caused by repetitive scratching behavior. The problem begins when your cat scratches himself excessively.

This leads to skin damage and infection. It can also result in painful sores called self-inflicted injuries.

The most effective way to stop this behavior is to cover your cat’s scratching posts with a non-toxic material such as newspaper.

  • Don’t Overfeed Your Cat

Overfeeding can lead to obesity. Obesity increases your cat’s risk for diabetes, kidney failure, joint disorders, and cancer.

It is essential to watch your cat’s weight closely. Please keep track of your cat’s food intake and weigh him monthly. If you see any signs of being overweight, consult your veterinarian.

Frequently Asked Questions

Your veterinarian will perform a thorough examination of your pet. They will examine your cat’s body, including the head, neck, chest, abdomen, legs, and tail. Your vet will also listen to your cat’s heart and lungs, feel her skin, and test her reflexes.

The prognosis for a cat’s health and well-being depends on various factors, including the specific diagnosis, the stage of the disease, and the extent of damage done to organs or tissues. However, most cats diagnosed with cancer will undergo treatment that may include surgery, chemotherapy, radiation therapy, and other medical treatments. The prognosis for individual cats can vary greatly depending on their overall health before cancer diagnosis; however, most cats generally recover from their cancers if treated effectively.

Yes. Cats who have Osteosarcoma can pass cancer along to their offspring. So, if you own multiple cats, ask your veterinarian whether testing them for osteosarcomas would be beneficial.

The average lifespan of a domestic cat is 12 to 14 years. However, some cats live longer than others. Some cats die suddenly without showing symptoms. Others live for several months or even years with advanced stages of Osteosarcoma before dying.

The following are some of the warning signs of Osteosarcoma:

  1. Painless swelling in the leg
  2. Swelling in the groin area
  3. A lump under the skin
  4. Difficulty walking
  5. Weight loss
  6. Fever

If you leave Osteosarcoma untreated, the cancer cells continue to grow and spread throughout your cat’s body. This means that the tumor grows bigger and bigger until it reaches vital organs such as the lungs, heart, liver, etc. Cancer then spreads through the bloodstream and forms new tumors elsewhere in the body. Eventually, this leads to death.

Cats are susceptible animals. They react differently depending on their moods, emotions, health conditions, and environment. If you want to know how your cat reacts to a particular situation, check out this list of symptoms and signs of cancer in cats.

Please contact your veterinarian immediately if your cat has any of these symptoms.

  1. Your cat’s eyes look sunken into his head.
  2. He seems lazy, weak, or sickly.
  3. His appetite decreases.
  4. He stops grooming himself.
  5. He seems interested in something other than playing.

Disclaimer: The information provided on this veterinary website is intended for general educational purposes only and should not be considered as a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a licensed veterinarian for any concerns or questions regarding the health and well-being of your pet. This website does not claim to cover every possible situation or provide exhaustive knowledge on the subjects presented. The owners and contributors of this website are not responsible for any harm or loss that may result from the use or misuse of the information provided herein.

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