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Greys and Melanomas - personal experiences?

I have a grey/white pinto Arab cross who is about 24 to 26 years old. He has one spot under his tail where he has a bump. It has not changed in 5 years. It doesn’t really look like melanoma but it may be.
I know of 2 greys that were euthanized due to melanomas.
Another friend had a grey OTTB that livec to late 20s with no melanomas.
4 grey ponies at barn I work at. One is 32 or 33 this year the other 3 are late teens. No melanomas for any of them
I would not get a grey again due to most liking to wallow in mud.

I’ve got a 28 year old grey with maybe one external melanoma (not entirely sure it is a melanoma) on his inner thigh. Interestingly, also an Arab cross.

I’ve known several greys with melanomas (none mine).

One needed a permanent trach tube to breathe.

One had masses on her rump that would break open and ooze inky black fluid down her legs.

One dropped dead in the pasture, necropsy found a melanoma in his chest bigger than his heart (and attached to it.) He had no external melanomas.

I won’t buy a grey.

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I’ve currently have 2 greys …my Dutch mare will be 12 this year …I’ve owned her since 4yrs old, and my Hanoverian geld will be 16yr and I’ve had him for about 6yrs now …my mare does have a couple very small melanomas and same for my geld …their size hasn’t changed and they don’t cause any issue for either of them …I did also have a grey tb mare who died at the age of 15…(I owned her about 10 yrs)not due to melanoma though …I guess for me the possibility of melanoma doesnt put me off of getting one at all …I have a horse of just about every other color as well and every single one of them has other problems :grimacing:

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I have had two grey horses. One no longer (I sold him) and one current.

The one I sold I bought as a 6 month old, and had to retire him from barrel racing at age 10. (found out he had a congenital issue with his neck) He never had any melanomas (that I know of). I still keep in touch with the family I sold him to for a leisure trail riding horse and he’s doing great.

The horse that I have now, I bought her at age 5. When I bought her, during the PPE, vet found a superficial skin lesion on her belly which we did remove and it was melanoma. Later that year, another one popped up on her jaw, which we removed. Knock on wood, she hasn’t had any more pop up. She is 7 this year and the thought is always in the back of my mind, that she could someday have internal ones or continue to have external ones. She’s a lovely horse and I wouldn’t trade her for the world, so I guess it’s worth the risk.

I had a friend who had to put down her grey horse about 2 years old. However, I think he was about 18 years old?? He had some internal melanomas that were causing some issues, including one around his rectum.

I’d add, if it isn’t common knowledge, that melanomas on grey horses aren’t exactly cancer that will spread to other organs, like human melanomas from sun damage. They are a factor of how the greying process handles melanin. But melanomas on nongrey horses can be true cancer


My pony had melanoma with only visible ones under the tail. He lived to be almost 30. Perhaps internal melanoma contributed to him doing poorly towards the end, because he started losing some interest in food and having some trouble eating. But he had a good, long life. I have seen melanoma in more obtrusive areas on other horses with varying outcomes on athletic career. I have not known one personally that had to be put down because of it. Had a friend with an older gray that we thought would eventually have to, but he wound up passing from colic that did not appear to be related to any internal tumors.

The top USEF 3’ hunter in the country has large melanomas. He won’t be winning a strip class but he won lots over fences with his kid who loves him. Check out the sidebar in the Chronicle horse show issue.

Exactly. It’s NOT cancer in grays and not life ending in many. I do wonder if there’s a difference in horses that get the oozing melanomas vs those that get the non oozing variety. So far, I have no experience with ooze.

What is worse than a grey? A grey Appaloosa. Or to be fair, the offspring of a grey crossed with an Appaloosa. Grey genes, pink skin.

My darling girl is 25 this year. She had a benign lump at 15 (not a mel.) that ended her ridden career as it was right on the girthline. She had a melanoma behind her right ear for years that threatened to interfere with her axis joint… then it flattened and now there is absolutely NO sign of it (thing was the size of a 50c piece - Aus). Now… she was dx’ed with nasal cancer. Found by chance but has spread up both nostrils. You can hear the obstruction (originally thought to be a slack vocal chord). No idea of timeframe.

Poor girl suffers terribly from sunburn on her face, all her skin has “pinked” out - she was mottled as a young horse and has vitiligo now so all her pigment is gone. Basically albino skin. White sclera around her eyeballs means she’s had spots frozen off of her eyes. She lives in a rug, a “hat” and a nose flap.

I assume after watching it happen on my horse (although haven’t looked around to confirm) that larger tumors die inside from lack of blood supply through the mass, then rupture and ooze because that dead tissue is necrotic. Tumors can rupture, ooze, and then heal without intervention, and be much smaller, although not sure how common that is.

I think it’s clear there’s a wide variation in severity of melanoma–how fast they appear, how aggressively they grow–and that’s it’s pretty likely that component is genetic and inheritable.

If the grey parent is alive & well without particularly notable melanoma in the mid teens, that’s at least suggestive that the grey get will be the same. But aggressive melanoma really sucks, and it’s sure not what you expect when buying a young, grey horse.

This paper is an interesting case review & literature review for those interested in the research. Full text:

There is much we don’t know, and research suggests (at the least) that there’s a lot more metastatic disease happening than we think:

“Reports indicate that cases of equine melanoma rarely have clinical signs referable to metastases, despite a high metastatic rate being detected at necropsy

(Emphasis mine.)

There is this as well.

From the summary:
“Debate surrounding the nature of equine melanoma has resulted in an underestimation of its life-threatening potential. Contrary to popular dogma, the variable, often slow, rate of growth commonly associated with equine melanoma does not warrant benign classification. Equine melanoma is a malignant neoplasm with the capacity for local invasion and metastasis.”

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Fantastic paper, yaya.

This bit is certainly sobering.

“Dermal melanomatosis is a condition seen in grey horses
involving multiple cutaneous masses, with at least one of the masses presenting in a ‘typical’ location. These typical sites include the undersurface of the tail, anal, perianal and genital regions, perineum, and lip commissures (Seltenhammer et al. 2004). Like discrete dermal melanoma, dermal melanomatosis is most frequently seen in mature horses. However, dermal melanomatosis is associated with a slightly older average age of 17 years, a figure at variance with our studies in which the mean age was <10 years (Robertson 1996). According to Valentine (1995), these masses are not amenable to surgical resection and are very likely to be associated with visceral metastasis. This condition is considered to be potentially fatal.

Yeaaaah, that’s my 13 yo mare right there.

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My mare too.

She had a brief rectal bleed last year. I was sure it was melanoma related but the vet found no masses. It had stopped by the time I got her to the vet and the vet could only come up with a ruptured hemorrhoidal vein. No reoccurrences since then.

Her first melanoma occurred at 2yo. Right under where the tail joins the body and it was very macerated and oozing due to tail swishing. I had that one removed. Now at 21, she has 10-12 on the underside of her tail. One is about 1/2 inch in diameter and the rest are pencil eraser size. I guess we will see what happens.

I know one person that has a 20 something gray mare euthanized due to tumor burden that was interfering with her elimination. It definitely can be fatal.


I have an early 30s-ish (not sure of her exact age) Arab mare. She had a very large tumor removed from just left of her anus in fall 2016. Since then she has developed a number of new tumors in the same area, but nothing nearly as large as the one that was removed. She will periodically have tumors under the tail rupture and ooze black “melanoma gunk”, but I just keep the area very clean and everything always heals back up.

We have a QH mare at my barn in her early/mid-20s who is pretty riddled with under-the-tail tumors. She’s still being ridden regularly and healthy in all other aspects.

Even though my girl is still kicking in her 30s, and I would probably still be riding her if she wasn’t unsound in other ways, I’ll never own another grey. I know there are all sorts of ways that horses can get sick and injure themselves, but I’d prefer to at least eliminate unavoidable melanoma from the list. The stress of everything surrounding her surgery in 2016 was enough for me lol.

This thread is interesting to me. I never realized such disdain or preference against grays. I have a big gray (I have the hardest time calling him gray because he is white from head to toe, but I know, I know…) and he’s 12 and has no issues.

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Once you have one prematurely die on you due to melanoma, it’s hard to get excited about it.

Most of my childhood horses were gray and lived to ripe old age with no issues. But watching a friend lose her 6 year old to internal melanoma was gut wrenching.

It’s my favorite color of horse, in theory, but they are ticking time bombs.


I used to quote Phillip’s 2013 article as the gold standard in background information regarding melanoma. I just went looking for the link again and found this very excellent summary article with a 2023 publication date:

Kind of heavy going in the details but gives a really good overview of the many treatments and background information about melanoma. Also - it’s free!

And here’s Philips article as well, even though 10 years old now, still has some good information. It is, unfortunately paywalled at $27.95.

Oncept used for horses is technically administered off label. Rumor had it that Phillips was conducting a study to place it on label - but that was 3 or 4 years ago and I haven’t heard much since.

So many questions still remaining about melanoma in horses, but it’s encouraging to see that researchers are finally delving into it. Much preferable to the out of date but common response I got when I first started looking into treatment that there was “nothing you could do about it”.

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I’ve had 2 grays–both Thoroughbreds. The first was back in the 70s and he didn’t pass because of melanoma that I know of. I didn’t own him at that point. My most recent gray developed lots of melanomas. They progressively multiplied starting at about age 15 under his tail and dock region. Based on previous post, his oozed. They were nasty. As they grew worse, he also became an outcast with my other 2 OTTBs, even though he’d been way dominant before. My understanding—and even though I couldn’t see it, I believe it—that as much as I could see externally, it was much worse internally. I believe it because I watched his entire personality change—so don’t jump my sh–. I put him down at 19 and I won’t buy another gray. Don’t get me wrong - I’ve lost other-colored horses for weird things and we all die from something, but if I have a choice among all the horses out there, I’d decline on gray. That’s just me.

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I’ve owned 2 greys and close friend rescued two grey oldies from the kill pen.

My heart horse I never found melanoma on. He lived a happy life but at age 19 he fell down in the pasture and couldn’t get up. He couldn’t use his rear end. Vet thought it could have be something in his back/rear that was bound to show up. Can’t rule out that there could’ve been an internal melanoma.

The second grey I had was 14 years old. I got him sight unseen and it was kind of a goodwill situation thing. He had the pencil eraser melanoma on his dock and some larger ones just starting to ooze lower down. My friend was riding him one day and he started backing up and just collapsed. Never diagnosed but we think it could’ve been an Aneurysm or heart attack. Again I can’t rule out internal melanoma on this death.

My friends two oldies came to her covered in melanoma. She put one down within a month due to huge ones in his month starting to prevent him from eating. The mare is still living out her days but her back end is covered in them.

I am in the club of steering away from greys in the future. Its just one extra thing to worry about.

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