Osteosarcoma: How to Diagnose and Deal with Bone Cancer in Dogs
Dogs are vulnerable to a number of diseases and health issues. One of the most aggressive and difficult to treat is osteosarcoma or bone cancer in dogs.
Osteosarcoma is an invasive cancer that originates from bone cells. It is a difficult cancer to diagnose in its early stages. Due to the delayed diagnosis, this cancer spreads throughout the body very quickly.
Every year 8,000–10,000 dogs suffer from osteosarcoma in the United States. Unfortunately, often times amputation becomes the only possible treatment option to provide some relief to dogs ailing from this cancer.
Dogs Most at Risk of Developing Osteosarcoma
Usually larger dogs are at a higher risk of developing osteosarcoma. These include the following breeds:
- Great Dane
- Irish Setter
- Saint Bernard
- Great Pyrenees
- German Shepherd
- Bernese Mountain Dog
- Doberman Pinscher
- Golden Retriever
Signs of Bone Cancer in Dogs
Diagnosing osteosarcoma in dogs is difficult, but there are small signs and symptoms you can look for to try to catch the disease as early as possible. These may help to give you a better understanding of this medical condition.
- Swelling below the elbow or near the knee due to the tumor developing near the growth plates.
- Lameness in the affected limb because the swelling causes pain and discomfort for the dog.
- Weakness in the affected bone which can get fractured from even a minor injury.
- Lethargy and lack of energy in the dog.
This type of bone cancer in dogs is very difficult to diagnose in the early stages of the disease. A vet uses X-rays to identify osteosarcomas as the bones affected with cancer have a moth-eaten appearance in the X-rays. On top of that, an examination of tissues, and blood tests are done to check for underlying medical conditions.
By the time this type of cancer is diagnosed the tumors have already spread to other parts of the body.
The lungs in particular become infected with tumors.
Initially, the metastases is small, and only in 10% of cases a chest X-ray will reveal them. But due to the high tendency of the spread of this cancer, especially in the lungs, the treatment is designed as if dog has metastasis. Most of the time, the death of the dog is due to metastasis of osteosarcoma in other body organs.
The Three Stages of Osteosarcoma
- First – Stage 1: Low-grade tumor with no signs of metastasis
- Second – Stage 2: High-grade tumor with no signs of metastasis
- Third – Stage 3: Tumor with metastasis
Due to the metastasis and appearance of this type of bone cancer in dogs, sometimes osteosarcoma is confused with other tumors and vice versa. Other infections like fungal bone infection produce symptoms similar to osteosarcoma. So, a vet will generally recommend a biopsy for proper diagnosis, and to rule out any other disease or infection.
Prior to the surgery the vet conducts blood tests for bone alkaline phosphate and total alkaline phosphate. The results will help them to understand the prognosis of the disease better.
Treatment for Bone Cancer in Dogs
Intensive treatment and therapies are generally recommended to treat osteosarcoma. However, because it is such an aggressive cancer, the treatment will just extend the life of the dogs.
At best a treatment will improve the quality of the dog’s remaining life, but a complete cure of the disease is often not possible.
Amputation and Chemotherapy
The most common treatment for osteosarcoma involves amputation of the affected limb. Afterwards, this is followed-up by sessions of chemotherapy to destroy any stray cancer cells that may have traveled to other parts of the dog’s body. Chemotherapy is ineffective in dogs that are not candidates for surgery, and the tumor is not removed from their body.
If a tumor is small, and is detected in the early stages with the right spot being located, then surgery could be performed. A surgeon will remove the affected bone which is then replaced with a bone graft and metal implant.
However, there are several complications associated with this surgery. For instance, dogs can fail to own the graft or they can develop infections. Also, it’s possible for a recurrence of the tumor. Chemotherapy treatment is generally provided after surgery to reduce the chances of the tumor coming back.
If amputation or surgery are not possible treatment options for the dog, then veterinary oncologists typically take palliative measures to relieve the pain. This includes a combination of radiation therapy with oral pain relievers, and an injection of a bisphosphonate. Even though this treatment won’t kill the tumor cells, but it can provide the dog with some relief from the pain, and improve their quality of life.
Prognosis for Osteosarcoma
For dogs with osteosarcoma survival time depends on the severity of the disease, and the type of treatment they receive. So, the survival time for dogs that undergo amputation to remove a tumor without chemotherapy is generally 3–5 months. Even though limb amputation relieves the pain, but the metastasis of the cancer cells will eventually kill them.
The life span of these dogs can be extended by 1–2 years from the time of diagnosis, and their life span can possibly be extended slightly more if surgery is followed-up by chemotherapy.
Those dogs who don’t undergo amputation or surgery will live for just 1–2 months. Their life span can be extended slightly more by combining oral pain medications with radiation therapy, and bisphosphonate injections.
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