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OVERVIEW AND PREVALENCE OF CANCER IN DOGS

Research shows that 50% of dogs older than 10 develop cancer at some point. Increased cancer susceptibility may be due to environmental factors, or it may simply be that dogs are living longer as vet medicine and care improves. It is well known that the risk of cancer development grows with age in both dogs and humans.

A cancer diagnosis in your furry friend can be life-altering, but thankfully, over 50% of tumors in dogs are treatable. Additionally, if detected early, it can be better managed. Therefore, taking your dog for regular health checkups at the vet and being aware of your dog’s habits so that you can see subtle changes in their behavior can help with early detection. Being attentive to your dog allows you to detect signs and symptoms that can lead to an early diagnosis and impact your dog’s length and quality of life.

Adenomas and adenocarcinoma are the most frequent tumors diagnosed across dog breeds. These tumors begin on ductal tissues, and you can easily visualize them. Over 60% are on sexual organs, the other sites being the head, neck, and eyelids. Adenomas are benign tumors (non-cancerous), but they have the potential to develop into adenocarcinoma, which is cancerous. Fortunately, the increasing rate of neutering pet dogs over the last few decades has decreased the frequency of these tumors. While you may interpret this as promoting neutering, there is some contrasting evidence that shows other cancers have increased with the rate of neutering. These cancers include mast cell (immune cell), melanocytic (skin), and hemangioma (blood vessels and spleen) cancers. Therefore, speaking with your vet is key to determining if neutering and spaying are appropriate for your pet.
 

Cancer Prevalence Across Breeds

While both mixed breed and purebred dogs can develop cancer, some reports show the incidence is higher in purebred dogs. However, more recent studies challenge this assumption. While the heightened risk of cancer in purebred dogs is still in question, reports demonstrate that cancers affect different dog breeds differently. For example, with an incidence rate of 60%, Golden Retrievers are the breed with the highest risk of developing cancer. The most common types of cancer in Goldens are hemangiosarcoma (cancer of the blood vessels and spleen) and lymphoma (cancer of the infection-fighting lymphatic system). In contrast, Boxers are more likely to develop mast cell tumors, while Schnauzers more commonly develop squamous cell carcinoma, a form of skin cancer.

In addition to breed, size can impact susceptibility to cancer in dogs. Smaller dogs are three times more likely to develop mammary tumors than big dogs. But reports show that smaller dogs are less likely to develop other cancers in the body than large dogs. This mortality difference may be due to the hormone known as insulin-like growth factor (IGF-1). While IGF-1 facilitates normal bone and tissue growth, the hormone can also play a direct role in tumor formation in dogs. Due to their size, small dogs may have low concentrations of IGF-1, resulting in lower cancer risk overall. For example, cancer risk in Chihuahuas and Maltese is less than 10%.
 

Knowing your dog and their risk of cancer is a great start to prevention. Furthermore, careful attention to your dog’s health and behaviors, and regular check-ups with your vet, will ensure an early diagnosis and proper care for your dog.

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Last Updated: September 11, 2022

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