Eighty percent of gray horses develop melanoma during their lives, and for some it can be debilitating. Melanoma vaccination is a potential treatment option.
Historically, vaccines have been made from a sample of the horse’s own melanoma. This is called an autologous (coming from the self) vaccine. The theory behind this type of vaccine is that injection of the vaccine back into the horse stimulates the immune system to fight the tumor cells. But it turns out that this is not very effective in horses with melanoma. I have treated several horses with autologous melanoma vaccine in past years, and was not satisfied with the result.
But in recent years, vaccines have become much more sophisticated. At least one vaccine company takes melanoma DNA and links it to a bacterial DNA segment. This stimulates the immune system to fight the bacterial DNA, but also causes some immune system “confusion”. The body is tricked into identifying the tumor cells as foreign, and so it mounts an immune response against the tumor cells too.
In this procedure, melanoma samples must be surgically removed from the horse. The sample is put in preservative and sent to the specialty lab. There, the cells are examined to determine their suitability for use in the vaccine. In some cases, the cells may need to be cultured to increase their numbers. The vaccine is made and sent back to the vet for storage and administration on a set schedule.
A commercial canine melanoma vaccine also shows some promise for equine melanoma . As of the time of this writing, efforts are being made at FDA approval for its use in equine melanoma.
YOUR VET’S ROLE
Your vet should know the status of melanoma vaccination and should be able to select a lab that can show some evidence of effectiveness for their product. Your vet will cleanly remove a melanoma from your horse and submit it, and then will help you coordinate vaccine administration. Your vet will need to give the vaccine.
Talk to your vet about vaccination as a treatment option for melanoma, especially as a means of helping horses with severe and widespread melanoma.
The melanoma vaccines currently on the market require a significant financial investment, so be aware of the cost. There will be an initial appointment at which melanoma is harvested through removal of some masses, and follow up appointments with your vet, for vaccination.
In the commercial vaccine trial, the canine vaccine is administered every 2 weeks for 4 treatments followed by a 6 month booster.
This Treatment Might be used for a horse exhibiting these signsRelated Observations
Related DiagnosesThis Treatment Might Be Used for these Diagnoses
Know Related Treatments
Consider Potential Side Effects & Complications
Anaphylaxis or local reaction are possible using any vaccine.
The vaccine may not significantly change the appearance of melanoma.
Infection, pain or local swelling can take place at the melanoma sampling site.
Consider Reasons Not To Use This Treatment
Melanoma vaccination is unlikely to be helpful for horses that are already "sick from melanoma"- ie. they have had widespread metastasis of the tumors to organs. Once this happens, there is little hope for horses.
Is It working? Timeframe for effect
Prior to beginning a treatment protocol with melanoma vaccine, it is important to photograph and measure the melanomas. Expect improvement in the size of the melanomas over months, or at least, little growth.
Questions To Ask My Vet
- Are the tumors shrinking in size and, if so, how can we attribute this to the treatment?
- Can you explain the science that shows that this treatment works?
- What should I expect of the appearance of the melanomas after treatment?
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