Quarter horse with Malignant Melanoma

[Roadmix3]

Hi,
I have a 20 yr old dun quarter horse. He’s been really healthy his whole life. Nothing major or expensive with him. Unfortunately I think the lucky streak has come to a close.

This spring I just happened to notice a very tiny bump about an inch inside his left nostril. It looked harmless to me. And the barn manager agreed. I put a call into the vet and he said just to wait and see if it grows. Sure enough, couple months later, it had grown some. Not a lot, but some. By fall it was easily 3 times it’s original size (still small though). The vet came out, suggested it was a cyst of sorts and removed the bump. She did send it for testing. The results came back as a malignant melanoma! I now recognize the two small spots he’s had for years (one on his lip area, the other on his cheek) are probably melanomas too, but perhaps the benign version as they have not changed in years.

Now i am uncertain on what to do. I have put a call into two universities in the area. One said usually malignant melanomas in non-grey horses carry a poor prognosis/he would need to check with his senior vet to get ideas. The other university offered me a couple options. One being the melanoma vaccine. It is expensive, and not always successful. So I am hesitant to try it on a horse of his age, but yet I am willing to go through with it if it’s going to help him.

Anyone with experience in malignant melanomas on non-grey horses?! Especially ones that have tried the vaccine??? I could use some help! Thanks in advance!

[Simkie]

We’ve had a couple threads about Oncept for grey horses. Realize you’re looking at something different, but they still might be useful?

https://www.chronofhorse.com/forum/forum/discussion-forums/horse-care/261149-melanoma-oncept-october-2018-update-post-159

https://www.chronofhorse.com/forum/forum/discussion-forums/horse-care/10033384-oncept-melanoma-vaccine-for-grey-horses-with-melanoma

[costco_muffins]

Our vet just did the “poor man’s version” of the autogeneous vaccine. She basically took a chunk of his melanoma and inserted it into his neck. She said she’s seen some success with it and that the horses can start to recognize the bad tissue and slow its growth. It doesn’t reverse what is already there, however. For us, for a mid-level, 12 y/o schoolie, this was the only option that we could really consider. A $3000 maybe it would make a small difference vaccine wasn’t in the cards.

[Roadmix3]

Interesting option… thanks for sharing that! Was the horse in question a grey? Has it been long enough to tell if it’s helping anything? Thanks again

[oldernewbie]

I am not a vet! But I have used the melanoma vaccine Oncept successfully on my gray horse. But no matter how great I think Oncept is, I would be getting a second opinion from a veterinary oncologist before I’d drop the $$ for Oncept in your situation. It was always my understanding that the melanomas grays get are different than malignant melanoma that non grays get. If it were me, I’d be contacting the closest vet school for a second opinion. OOPS - I just saw that you did that. Well, in my humble opinion, you need to talk to someone who doesn’t automatically equate melanoma with Oncept.

Try to locate a veterinary oncologist… I know Ohio State has one, I’m sure other schools must have one as well.

ETA: Just re-read Philips article about melanoma to see what he says about non grays and the answer is not very much.

[costco_muffins]

@Roadmix3

Interesting option… thanks for sharing that! Was the horse in question a grey? Has it been long enough to tell if it’s helping anything? Thanks again

Yes, he is gray. It has only been two weeks… So not sure. His melanomas grew from 2cm in width to 20cm in width over two months and are in the muscle of the haunch at the site of a previous muscle tear and trauma.

[gnu]

I had a bay TB diagnosed w/ malignant melanoma when in his 20’s. It is rare in non-greys, and spreads quickly. When I first saw the tumor, it was small and showed little change for nearly two years. It was biopsied and diagnosed when it began to enlarge. My vet removed as much of the tumor (located about 12" below the dock in the hairy part of the tail) as possible and used cryotherapy multiple times. He had two good years, then succumbed very quickly to a colic likely due to abdominal tumors. A few months after the first removal, it took off and developed a black tarry discharge. Subsequent removals and freezing resulted in shorter calm periods before it took off again. Vet felt that chemo was not a good choice. Only published paper I could find discussed a 12 yr bay TB. Ultrasound revealed many internal tumors in that horse. Good luck in managing it.

[Roadmix3]

These have all been very helpful. Thank you for taking the time to share. Now to decide on a treatment option.

[Roadmix3]

Just wanted to update this, just encase someone else in a similar situation decides to look around on the internet for help!

I took him to purdue large animal hospital. They were pretty conservative concerning the melanoma that was removed. It had been three weeks with no regrowth present. Which is a good sign. They took an x-Ray of his head, to look for anything abnormal. And they did find a faint mass somewhere in the soft tissues of his nose. They then proceeded with a scope into his nose to look for said mass, and could not find anything. So whatever it is, is in the tissues, or is scar tissue. They said since it’s not causing him issues, they felt comfortable leaving it alone. Especially considering his age. They then injected the original tumor site with Cisplatin. The liquid form. And we were on our way. The Cisplatin was very inexpensive, and the entire visit as a whole was inexpensive as well. I’m hopeful for him, that we can have a couple more good years together! Thanks again for the info and suggestions!