Osteosarcoma is a primary bone tumor and one of the five most commonly diagnosed cancers in dogs. Research has found correlations between these tumors and a dog’s weight and size.
What is it?
Osteosarcoma (OS), the most common canine bone cancer, accounts for 85 percent of all skeletal tumors, or about 25,000 cases per year in the US. It tends to be biologically aggressive in the distal radius of the foreleg (above the carpus or wrist) ”), the tibia / fibula of the hind leg and in the femur. However, OS can occur in other bones and sometimes occurs in the vertebrae and pelvis.
A pet insurance company report at the 2016 AVMA conference stated: “The prevalence of disease rose in the late Middle Ages, peaking from eight to eleven years. Thereafter, the prevalence decreases in line with the typical lifespan for large and extra-large individual dogs. Gender does not seem to be a significant risk, although male dogs are slightly more affected than female dogs. “
Signs and symptoms.
Sudden lameness with no apparent cause, swelling, and pain can all be indicators of the OS. As the pain increases, the dog may become irritable and less willing or able to move or exercise. OS-weakened bones are prone to fracture, which is often the case when the cancer is discovered. At the time of diagnosis, it may have metastasized to the lungs, making treatment more difficult.
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How is it diagnosed?
X-rays are the first test of choice for diagnosing a malignant bone tumor. On an x-ray, the OS makes the affected bone look like it is being eaten by moths due to the loss of normal bone tissue – or lytic, according to the veterinarian. Since other, but far rarer, conditions can also cause this appearance to lead to a definitive diagnosis, the next step is usually a fine needle aspirate or biopsy. both are done while the dog is sedated.
If the OS is confirmed, the veterinarian will examine the cancer to see how far it has progressed. Usually blood tests, urine tests, lung x-rays, and an ultrasound of the abdomen are involved. If enlarged lymph nodes are found, additional biopsies may be required.
How is it treated?
Because the osteosarcoma is fast moving and very likely to metastasize, the recommended treatment for bone tumors in the leg includes amputation of the affected limb, followed by chemotherapy. However, in some cases, amputation is not a viable option.
According to “Osteosarcoma in Dogs,” a 2002 article by Wendy Brooks, DVM, DAVBP, revised in 2019: “Most patients have a tumor on one leg and no visible tumor spread in the lungs. These are the patients with the best potential outcomes, and they are good candidates for amputation. Patients with high levels of arthritis in the other legs or with tumor spread in the chest are unlikely to be candidates for amputation. It may be better to keep the leg and simply use radiation therapy to relieve the pain. “
Other options may also be suggested depending on the location and type of tumor. In all cases, the treating veterinarian is focused on relieving the pain and doing as much as possible to stop or slow the spread of the cancer.
ELIAS cancer immunotherapy (ECI), a recently developed experimental treatment approach, was used in a study initiated in 2017 by researchers from the University of Missouri College of Veterinary Medicine. The aim of this unique study was to develop a “patient-specific, precision medical treatment” for bone cancer in dogs. Ultimately, they were able to use the dog’s OS to create a personalized vaccine that – unlike chemotherapy – targeted cancer-specific cells and left normal cells untouched.
In this study, the entire treatment protocol was completed in eight weeks, rather than the many months required for conventional chemotherapy. According to the report in the Journal of Veterinary Internal Medicine, the median survival of 14 dogs treated with ECI was 415 days, and five dogs survived longer than 730 days. All of these dogs had surgical limb amputation prior to immunotherapy, but none received chemotherapy.
Research like this is part of something called comparative medicine. Using resources created by advancing technology, scientists are looking for similarities and differences in canine and human cancers that will lead to better ways to prevent, diagnose, and treat the disease in both cases. (For example, the One Health initiative encourages collaboration and the integration of expertise between doctors, veterinarians and scientists.) For OS, this included studying the genetic profile of both species. Researchers found the profiles indistinguishable.
While OS isn’t as common in humans as it is in dogs, it makes up about 3 percent of cancers in children. Early limb-sparing techniques and novel combinations of treatments were used in dogs to optimize them for use in children and vice versa. In order to protect the limbs, instead of amputation, the section of bone affected by the tumor is removed and replaced with a transplant from a bone bank. sometimes the remaining bone can be regrown by bone transport osteogenesis.
Are Certain Races Predisposed?
In many breeds, there is less genetic diversity due to selective breeding for desired traits such as appearance or physique. The unintended result is that certain breeds are now at a higher genetic risk for certain diseases and cancers. Genetic risks associated with OS in dogs have been particularly well studied. Large and giant dogs – particularly the Irish Wolfhound, Greyhound, Akbash, St. Bernard, Leonberger, and Rottweiler – are most commonly affected. Bone Cancer Dogs, an online support group for owners of dogs diagnosed with OS, has a list of OS-specific clinical studies and other detailed information.