Horses occupy a unique niche in the world of ‘companion’ animals and veterinary medicine; a niche that within the past several decades is beginning to expand, and with this expansion, new therapies are being developed for equine diseases.

Young woman with a horseLike dog, cats and people, horses can develop many different types of cancer. The uncontrolled growth of abnormal cells (cancer) can invade healthy tissue to form local tumors or can spread through the blood or lymph system to all regions of the body. Cancer cells can also release chemicals that can cause further issues such as weight loss, depression, anorexia, fever and anemia.

Types of Equine Cancer


Melanoma is one type of cancer seen in horses. The incidence of equine melanomas, more frequently noted in gray horses, has been reported to reach as high as 80% in older animals. Notoriously difficult to treat, melanomas have benign and malignant variants. Melanomas can be locally invasive and metastatic and can vary from superficial dermal lesions to obstructive gastrointestinal lesions causing weight loss, constipation, and colic to neurologic involvement resulting in lameness and lack of muscle control. Their variable presentation and therapeutic resistance stems from multiple molecular mutations that result in the formation of abnormal proteins. These mutations, which occur in melanoma at considerably higher rates compared to other malignancies, disrupt the normal function of the melanocytes. In fact, the continuing evolution of individual tumors within individual patients make melanoma a constantly moving and diverging target.

Squamous Cell Carcinoma

Squamous cell carcinoma is a readily detected type of skin cancer, usually appearing around the anus, genitalia and around the eyes. Squamous cell carcinoma is highly invasive and will continue to grow and spread to nearby tissues if left untreated. This disease can be lethal, however, if detected early, surgical removal can be curative.


Lymphoma may be more difficult to detect than squamous cell carcinoma but can be just a deadly. Lymphoma is a disease of lymph tissue and is spread through the lymphatic system. Lymphoma may start in one lymph node and spread diffusely through organs such as the intestines and skin. Diagnosis is often made from clinical signs such as weight loss, tumor masses, edema diarrhea or blood changes.


Of the other common types of cancer in horses, sarcoids is one of the most common and perhaps the most unpredictable. Sarcoids may not spread in the same way as some of the other equine cancers mentioned, but the uncontrolled proliferation of the cancer cells is very difficult to treat and can become disabling if not caught early enough for surgical removal to be a viable option. Horses also develop breast, ovarian, prostate and testicular cancers.

Treatment of Equine Cancer

Employing special vigilance may be necessary to detect cancer in horses, and being on the lookout for any change in your horse’s routine, demeanor or unexplained changes such as lumps, bumps or sores that don’t heal can pay off for you and your horse.

The changing nature, constant evolution and number of accumulating abnormalities is the most challenging aspects of treating any cancer; making them moving targets for most therapies. However, the many accumulated mutations and resulting mutated proteins make melanoma an ideal target for IFx-VET. The powerful priming mechanism of IFx-VET ensures that all abnormal proteins associated with the tumor are presented to the cells of the immune system, thus focusing the immune response on multiple patient-specific mutated proteins and reducing the chance a tumor cell can escape immune detection.