Melanoma - Oncept - December 2020 - Update post 180

Good news about the eye melanoma lessening ! Phew ! Thats gotta be good to hear ! Is the Gaskin lump a melanoma ? What are your vets thoughts on Oncept so far ?

You know, it’s been a while since I talked to my vet about it, so I asked her. Will post when I get her opinion.

I would assume that the gaskin lump is a melanoma, but it has been stable and small and it doesn’t interfere with his movement. So, we are just watchful at this point.

Some comments from Mr Ay-rab’s attending vet. She mentions that they have had 15-20 horses try Oncept to date.

From our cases, seems that roughly half of the horses that we've treated have had some sort of a positive response to the vaccine (a couple of dramatic ones, like Monty [aka Mr Ay-rab], in which the lesions essentially went away after a couple of months on protocol) - there have been relatively few adverse effects, and among those, they were almost all minor (local swelling that went away within 24 hours), so it seems to be well-tolerated in horses.

What we are often asked about but have absolutely [B]*no*[/B] idea how to accurately answer is whether this vaccine can be used prophylactically, say, started early in young grey horses to prevent melanoma later in life. To my knowledge, there are no data reported on this type of use - given early enough, might very well give them vitiligo, who knows (which, incidentally, a colleague reported as an adverse effect in one of her treated patients)!

On the whole, our experiences with this product have been positive, with the worst outcome, really, being that it doesn't seem effective at all in some horses - AND, we have no good way to identify those non-responders before spending quite a bit of money testing the waters, so to speak... Biggest downside that we've identified so far = expense (!)
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So there you have it, straight from the source! Happy Holidays!!!

Thank you!

Thank you for the updates.

Wow! Just noticed that this thread is now over 18,000 views! I hope it’s been helpful! :smiley: Best of luck to all my fellow gray horse owning posse!

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So after 5 years of sailing through appointments at OSU, it’s been a wild ride for the last month.

Had the vet out for the spring dental and sheath cleaning appointment. When Mr Ay-rab dropped his penis after a little happy juice, vet noticed lumps that none of us had seen before, certainly not at his last sheath cleaning a year ago. Took pictures, sent to OSU, and new melanomas were suspected.

He had laser surgery Friday to remove the lumps on his penis and they were definitely melanomas. I also had them remove the hard lump on his gaskin that didn’t seem to be a melanoma. They found two others like it on his stomach and lasered those. I am waiting for the pathology report for these.

He got another Oncept injection while he was in recovery.

He spent a couple days at OSU recovering and came home today. No apparent ill effects - he came off the trailer in fine shape and seemed to be happy to be home. He has to spend time on stall rest until the sutures come out on his gaskin. So it will be a while before he resumes his role as king of the yearlings.

Here’s the really puzzling thing - nothing has happened at all in his old sites. His eye looks good, the very small lumps internal to his jugular groove are hardly noticeable, and the lumps under his tail remain very small. I really don’t know what to make of this. I don’t think we know enough to know what to make of it!

So we will forge on. Seems like his purpose in life is to be a science experiment, so we will see where this takes us.

I am sure someone will ask the logical question, which is am I sorry I started him on Oncept? Has it been a waste of money? My answer to both is absolutely not. I am pretty darn sure he wouldn’t be with us at all at this point without Oncept. He’s earned the right to have some money spent on his health since he has been exceptionally low maintenance in every other way.

Will keep you posted when I get the pathology report.

I don’t think there’s an emoji for what I feel right now - kind of a cross between WTF, horses, and relief that he is OK.


Wow, how interesting.

Any chance there are tissue samples from his original tumors? DNA analysis of those versus the new ones would be really intriguing. Not that you’d want to pay for that, but a vet on his team could perhaps get a paper out of it, along with the potential for some really nice data about equine melanoma!

Fingers crossed that this is a brief blip and nothing more than a curious footnote! Thank you again for sharing your journey here. :yes:


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Thanks for the update. Very interesting.

Last fall my mare has had three small lumps under her tail. She had one removed when she was just 2 y.o. She is now 17 so development is certainly not unexpected. When I checked her recently, I was dismayed to find at least 10 small but palpable lumps…bummer. My current ‘maintenance’ vet (who is nearing retirement) of course says there is nothing you can do about them. We can tell who hasn’t been keeping up:sleepy:. I am currently grounded for around 3 months due to foot surgery but will take her later this summer or early fall to our local referral hospital to see if they offer Oncept or at least get an idea when to get them de-bulked. I won’t let her tail become a big mass of tumors. Yes, there is something that can be done.


Today’s minor update: the lump on his gaskin, and two like it on his stomach, are not melanomas. However, vet called to ask to do more pathology tests because they are not sure what they are. Stay tuned.

Only my horse :confused:;):eek:

ETA: He also had a gas colic attack yesterday, poor guy. He’s doing fine today. For a horse that rarely sees a vet outside of his Oncept injections, he’s had quite the week!

So I got the pathology report today for the extra tests on the lump from his gaskin. The lump was a mast cell tumor, which the lit says is rare in horses. So of course we have it! My horse, the walking dermatology textbook! Excision is the cure, which is done now of course, and the margins were clear. So, only task now it to just keep an eye on his body for new growths.

He returned to his job of ruling the yearlings on Monday and seems to be just fine.

It certainly has been an experience with him! :eek::eek::yes:


Wow! It must at least feel good to know what the lump is and know that it is taken care of.

Thank you for sharing your journey’s ups, downs and insights. :yes:

Oh my gosh what a rollercoaster ride. Interesting how the Mast cell tumour is not targeted by the Oncept, only very specific to melanoma. It is like a science experiment alright !

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It was off to OSU this morning for Mr Ay-rab’s semi-annual Oncept injection. I was very happy with the results - no new mast cell tumors, old melanomas stable to pretty stable, no re-growth of melanomas on his penis. Perhaps the only area of concern is his eye as it seems to look different both to me and to Dr Burns, but not radically so. I think another trip to his ophthalmologist is in his future, but probably not until early spring unless something really goes haywire. I am not a fan of driving in the snow with a horse trailer.

He got his exam, injection, treats, hopped back on the trailer, and ruined a perfectly good grooming job when he got home by rolling on both sides in the muddiest part of the field. Life is good!


Hello. I have a 16 yr old grey Arab with a few melanomas in his sheath. I am serious about the oncept vaccine but have had trouble locating a vet that can do it. I have been quoted several thousand dollars for the injections, plus a office visit. Of course I am willing to do this but also would like to save some money if I can. does anyone have any suggestions? I am in Norco and my main vet cannot get the vaccine as he is not a oncologist nor a internist. Please help. Thanks, Robin


You know, around here (Ohio), Merial is letting regular horse vets without any special credentials buy and administer Oncept. All they have to do is buy the intradermal injector. This is a change from their earlier policies which did require a diplomate in oncology or internal medicine. It is nutty to me that they have apparently different policies in different parts of the country? I think I would have your vet run this up the chain of command (so to speak) at Merial and see if he/she can get a read that is more consistent with other parts of the country. Second choice is to try a vet school and see if they can help.

Good luck and let us know how it goes.

Hi. thank you! I did try Western University out here and left them a message. I hope they get back to me soon. If I was NOT in California things would be so much easier for sure.Or, the UK where they do it all the time.

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Be persistent. Not everyone knows about Oncept, and even if they do know about it, aren’t too motivated to start using it unless a client insists. Good luck!

It was time for Mr. Ay-rab’s 6 month Oncept injection - quite a different trip in the COVID-19 era! You pull in, call a phone number, the tech and intern come out and get the horse. Wait a few minutes, and the tech and intern bring back a horse with a new injection. No gaggle of vet students to take a look at Mr. A’s eye, no gossip with vet. I really miss that!

The good news is - he’s doing fine. No big changes. No adverse reaction to the injection. Took him home and we’re both happy!

Stay safe everyone!

Back to OSU today for Mr Ay-rab’s 6 month Oncept injection and mini Christmas party in the parking lot, since we can’t go in the building. Happy to report that he is doing fine. His fans at OSU miss him. Everything stable and small!

Hard to believe that in January it will be 7 years since his first injection!

Hope everyone has a happy holiday season and a safe and covid-free new year!!!

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