Posted on: November 18, 2022 Posted by: Petsynse Comments: 0

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Dog with three legs sitting on a road

None of us want to consider the possibility of our pups being seriously unwell. However, it’s important to be aware of some red flag symptoms, which could indicate something serious is going on. Osteosarcoma is an excruciating and aggressive form of cancer. So, if your dog has had this heartbreaking diagnosis, you must understand your options and the prognosis.

Table Of Contents

What Is Osteosarcoma In Dogs?

Osteosarcoma is a painful and aggressive bone cancer in dogs. It most commonly affects the bottom of the radius (just above the wrist joint in the front leg), the top of the humerus (just below the shoulder), the femur (just above the knee in the back leg), or the tibia (just below the knee). Unfortunately, by the time osteosarcoma is diagnosed, it has usually spread to other areas of the body (metastasized).

Less commonly, osteosarcoma can affect other sites in the body, such as the skull, spine, ribs, or soft tissues.

What Causes Osteosarcoma In Dogs?

As with most cancers, the exact cause is not yet known. There is likely a combination of genetic and environmental factors at play. However, we know that certain dog breeds are at higher risk of developing osteosarcoma. It is more common in large and giant breeds, such as Rottweilers, Greyhounds, and Irish Wolfhounds.

Osteosarcoma In Dogs Symptoms

The most obvious symptom in dogs is lameness, which may be intermittent initially but tends to progress to a non-weight-bearing lameness, meaning the dog cannot put the leg down. The lameness may initially respond to anti-inflammatory pain relief, but never for long. After around a week or so, the pain relief tends to be ineffective.

Other symptoms of osteosarcoma in dogs include:

  • A firm swelling, which is painful to touch and possibly hot 
  • Restlessness, since the dog is unable to get comfortable
  • Lethargy or lack of activity
  • Decreased appetite
  • Shaking or trembling (due to pain)
  • Fever
  • Muscle wastage
  • Swelling elsewhere in the body (less common)

While all of these symptoms can also have other causes, if you notice any in your dog, you should book an appointment with their veterinarian as soon as possible.

How Is Osteosarcoma Diagnosed In Dogs?

Your vet will start by asking you some questions and examining your dog. Initially, they would most likely arrange an X-ray to try and understand the cause of your dog’s symptoms.

If your dog’s leg swelling is cancerous, the X-rays will show specific changes in the bone. The bone will appear destroyed as the tumor destroys the surrounding bone. Sometimes, this can cause the bone to fracture (break). Your vet may also X-ray the chest to look for signs that the cancer has spread.

Sometimes no further tests are needed, as a presumptive diagnosis can be made from X-rays, symptoms, and physical exam. Further investigations may include:

  • A bone biopsy for a definite diagnosis – The appearance on an X-ray can look similar to other conditions, such as an infection in the bone (osteomyelitis). If needed, a biopsy can be done using a Fine Needle Aspirate (FNA), where a needle and syringe are used to suction cells from the area. However, sometimes this is inconclusive, and a true biopsy is then needed.
  • Fine Needle Aspirate (FNA) of lymph nodes – FNAs of the lymph nodes closest to the tumor can help to determine whether cancer has spread.
  • CT (Computed Tomography) scans – This is a more advanced imaging method, which gives a better idea of the extent of the tumor and the damage it’s caused. CT can also detect tumor spread early on when it’s too small or subtle to show up on X-rays.
  • Blood work and urinalysis – This gives an idea of your dog’s overall health, which helps when making decisions about treatment options.

Your veterinarian will walk you through all the diagnostic tests they feel are necessary.

Treatment For Osteosarcoma In Dogs

Whether or not to treat osteosarcoma in dogs is a very personal choice. Unfortunately, the outlook for osteosarcoma is poor. Whatever you decide, the most important part of treatment is pain relief and ensuring good quality of life. 

Unfortunately, the progression of osteosarcoma in dogs is very rapid. By the time of diagnosis, most cases will have already spread, even if the other tumors are not yet visible. This means treatment usually involves a combination of treating the primary bone tumor plus the metastases (the other places it has spread to). However, there are some treatment options that your vet may mention to you.

Amputation

While this sounds drastic, most dogs cope very well on three legs. However, naturally, the suitability of amputation will vary case-by-case. If your dog also has severe arthritis, amputation is unlikely to be an option since it would put too much pressure on the remaining limbs. 

Amputation alone can remove the primary bone tumor and can also be used for pain relief. However, it will not address any spread.

Limb-sparing Surgery

Depending on the tumor’s location and size, the limb can sometimes be saved. Sometimes only part of the bone can be removed without removing the whole limb. Sometimes metal implants can be used to maintain the structure of the bone. However, limb-sparing surgery is an advanced surgery that can typically only be carried out at referral (specialist) centers. It is also unsuitable in many cases due to the extent of the tumor.

Radiation 

Radiation can be used on the primary tumor as pain relief. It will not remove the tumor nor deal with any spread.

Chemotherapy

Chemotherapy can be used to address tumor spread, so it is often used alongside surgery in an attempt to prolong survival time. Usually, the earlier chemotherapy is started, the better the outcome.

Chemotherapy is often very well tolerated by dogs. However, there can be side effects such as nausea, poor appetite, diarrhea, and lethargy. Sometimes the side effects come on at the start of treatment but don’t last long. 

Bisphosphonates 

Bisphosphonates (a group of drugs) can be used for pain relief and to slow the bone destruction caused by the tumor. They act to strengthen the bone.

Pain Relief 

Pain relief is best achieved using a combination of drugs. Osteosarcoma is very painful, so if you opt for palliative care only, the pain relief is unlikely to be effective for very long.

During the final stages of osteosarcoma in dogs, your veterinarian will explain how to decide when it’s time to say your final goodbye and your options when the time comes. While it’s a heartbreaking decision for any pet parent to have to make, euthanasia is the kindest option if your dog’s pain is not being controlled or their quality of life is poor. Having these discussions with your veterinarian ahead of time can help you feel prepared when the time comes.

It’s important to note that you don’t have to proceed with treatment. Many owners decide to euthanize once they have a diagnosis to avoid suffering. The cost of treatment needs to be considered, too, since treatment costs can be high. The costs of frequent vet visits, complex surgery, advanced medications, and referral soon adds up.

What’s The Prognosis For Osteosarcoma In Dogs?

A dog’s life expectancy will vary, depending on how quickly the diagnosis was made, the extent the tumor has spread, and the treatment chosen (if any). Sadly, most dogs don’t survive more than a year after diagnosis, regardless of the treatment chosen.

With palliative care only, most dogs are euthanized within 2-12 weeks. With amputation or limb-sparing surgery, dogs can live up to around 4-6 months after surgery. If you add chemotherapy on top of surgery, dogs can survive up to 12 months.

Keeping Your Pup Healthy & Happy

When considering your options, it’s important to remember that quality of life is much more important than quantity. Whatever you decide, your veterinarian will walk you through each step of the way. No choice is right or wrong here, as long as your dog’s quality of life is at the center of the decision-making process. If your dog is uninsured, you might consider pet insurance so that if your dog does get cancer, you will be financially able to help him battle this horrible disease.

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