Oncology

Horses are commonly affected by skin cancer, with sarcoids, squamous cell carcinoma, and melanoma occurring most frequently. The internal medicine and surgery team at the Equine Medical Center uses a combination of chemotherapeutic agents, surgical excision, H-FIRE treatment, and laser ablation to treat all types of skin tumors in horses.

Equine surgery faculty member Elsa Ludwig has extensive experience treating cutaneous tumors, utilizing multimodal therapies to improve the resolution of skin cancers. Ludwig introduced the novel treatment modality, H-FIRE, to the Equine Medical Center. H-FIRE, a form of electroporation, when used in combination with local chemotherapy, has been shown to increase the success rate of cutaneous tumor treatment and is an exciting addition to the Equine Medical Center.

Skin cancer requires prompt treatment to maximize the chances of a successful outcome. If you think that your horse might have a skin tumor, contact your primary care veterinarian or make an appointment for evaluation and treatment at the Equine Medical Center.

In recent years, the equine medicine community has made great strides in diagnosing and treating systemic cancer in horses. Clinical signs of systemic cancer, which can be subtle in horses, may include lethargy, poor appetite, and weight loss. Equine Center internal medicine faculty member Krista Estell has a special interest in equine oncology and has treated several horses with systemic cancer, including lymphoma and metastatic squamous cell carcinoma.

Treatment often consists of a combination of laser-assisted surgical excision and ablation, along with intralesional and topical chemotherapeutic agents. The local delivery of chemotherapy drugs avoids the many side effects commonly associated with their systemic use.

More versatile than a scalpel, surgical lasers deliver light or heat to incise, coagulate, or vaporize tissue. The advantages of laser surgery for treating tumors include the following:

Laser surgical sites experience less bleeding and swelling than conventional surgical wounds. The carbon dioxide laser creates a clean, bloodless incision and can also vaporize tissue masses.
The carbon dioxide laser is controlled enough that corneal tumors can be vaporized from the surface of the eye.
Surgical procedures performed with lasers can often be performed on standing horses on an outpatient basis. Horses treated by this method leave with no external wound.

High-frequency irreversible electroporation (H-FIRE) technology originated in the human medical oncology field and has recently been used to treat tumors in dogs and cats. H-FIRE is now available at the Equine Medical Center – one of only two locations in the United States - as a skin tumor treatment option for horses.

This non-thermal tumor ablation procedure can be used to treat sarcoids, melanomas, squamous cell carcinomas, and some rare skin tumor types such as myxoma, with great success.
Electroporation is the application of electrical pulses to tissues, increasing the membrane permeability of the locally exposed cells, which enhances the ability of drugs to cross the cell membrane. This allows for lower chemotherapy doses, which decreases surrounding tissue injury.
H-FIRE technology enables the majority of horses to be treated standing and sedated, with local anesthesia of the area of interest. On occasion, treatment under general anesthesia may be necessary due to the temperament of the horse or the location of the tumor.
The vast majority of skin tumors that are treated with H-FIRE and chemotherapy do not recur following the treatment series, including cases that have undergone prior, unsuccessful tumor therapies.