Vaccine Study for Gray Horses with Melanoma

The University of Florida Large Animal Hospital is currently recruiting gray horses with melanoma for a clinical research trial.  This investigational trial is for the development of a vaccine for the future treatment or prevention of melanoma in horses.

  • Inclusion Criteria: Any gray horse recently diagnosed with melanoma and that does not have other life threatening diseases.
  • Treatment: Participation involves a series of visits to the large animal hospital at the University of Florida. At the first visit, the melanoma is biopsied and the horse receives its first vaccination. Three more vaccines are given at monthly intervals, then follow-up visits are scheduled 1 and 6 months, and 1 and 2 years later.
  • Cost: Clients are expected to pay in advance for the cost of all visits.  The total cost is $1883.70 or $1858.70.  In brief this includes (1) $558.70 (if paid by credit card) or $533.70 (if paid by check) for vaccine preparation and 4 vaccinations, and; (2) $1325 Large Animal Medicine package for an initial staging examination and 4 follow-up staging examinations.  This package reflects a discount of $775 from the usual cost of these services to encourage participants to come for all scheduled visits.  Please call the Large Animal Hospital at 352-392-2229 for more information.


Melanomas are common in gray horses and rare in other breeds. They begin appearing when gray coloration is complete (usually after 5 years of age). By 15 years of age, 80% of gray horses have visible malignant melanomas. Most melanomas are located under the tail, around the anus, or around the genital areas. A less common location is around the head, especially the lips and the salivary glands inside the mouth. Melanomas increase in size, become infected, and bleed, and eventually may obstruct the anus. A minority of melanomas in grays, and most melanomas in other horses, will spread to other organs and eventually cause death. Dr. Rowan Milner at the University of Florida College of Veterinary Medicine has developed a vaccine for treatment of melanoma in dogs, a highly fatal form of cancer. Reported results look promising after several years of studies. He has also created the vaccine used in horses which is a different version of the vaccine used in dogs.  Our expectation is that the melanoma(s) will not continue to enlarge after vaccination. It is our hope that they will in fact shrink or disappear.