Large Perianal Melanoma (TW: Picture included!)

[MaiTai]

All,

Posting to see if anyone has experiences with melanoma de-bulking for significant lesions and the pros/cons of a procedure.

I have a 21 year old Warmblood cross mare. When I purchased her in January, I noted that she had significant melanomas under her tail and in the perianal region. (She also has one on her muzzle and on her inner right hind, as well as what we presume is a melanoma (though it is covered) near her salivary gland.) The melanomas appear to have grown in the past 8 months, to the point where her rectum is now not visible.

She does not appear to be bothered or in pain from these tumors, and has no current issues defecating. (They obviously get messy with manure, but she is happy to have me wash them off. I have spent more time than I care to admit closely watching her poop, and there is no resistance as she passes manure.

I consulted with one local lameness vet (at the farm on a different call, so I just asked their opinion) who advised against surgery, saying that melanomas tend to grow back and these surgical sites do not heal well. They did mention Oncept or other autologous vaccines as a possibility, but did not recommend surgery. (Oncept would require transportation to Cornell, which is about 6 hour round trip; I do not have a truck/trailer yet, so would have to arrange shipping.)

My primary veterinarian consulted with a veterinarian at Cornell on my behalf, who recommended excision/debulking surgery due to the tumor size, followed by vaccination with Oncept (first choice) or Torigen (second choice.). (The pro of the Torigen is that she would not have to travel back and forth; after vaccine creation, my primary vet could administer the shots.)

The surgeon did say that the wounds would likely dehisce, and that I would likely be dealing with managing wound care at home as they closed by second intention over approximately 8-12 weeks, but felt that the surgery would help make her more comfortable and would hopefully enable her to live a longer life. The surgery would be done standing, with sedation and a local block and/or epidural. I should note that the surgeon at Cornell has not yet seen the mare in person, so much of this is assessment is based on review of photos; obviously, she would be evaluated at Cornell first prior to initiating any surgery.

Surgery plus vaccination is looking to cost me, at minimum, $7500. This cost is high (and, frankly, is higher than what I paid for the horse; I bought her to be a safe, sane, happy hacker type with good manners that I could retire at the farm I am currently building: she’s all that and more) but is not an impossible obstacle, and if the surgery were to make a big improvement in her quality of life, I would pursue it. This horse is a total pet, and will be retired at home to my farm to retire after her riding career (such as it is; we bop around 2’ fences and hack slowly on the trails ) is over. I have no problem pursuing all medical options for oldsters, providing those options are in the horse’s best interest and are humane; comfort is the goal.

My concerns (other than cost) are the pain associated with the procedure, length of recovery, and likelihood of surgical complications. Again, my priority is that the mare is comfortable and happy. I’ve always heard that (barring significant internal complications) “something else will kill them before the melanoma does,” and given her age, I’m hesitant to put her through a surgery that might not benefit her. At the same time, however, she is in otherwise excellent health–she does has coffin join arthritis but is well-managed with Equioxx and Noltrex–and happy, so I am anxious that the melanomas will continue to grow and “block” the rectum, resulting in an impaction emergency or otherwise terrible colic, etc., but don’t know if this is likely or not.

I guess I’m just looking to bounce this off of others who may have been in a similar situation and see the success/outcomes of a srugery/treatment plan such as this.

ETA: Also curious if anyone has done Torigen or Oncept instead of surgery, or prior to surgery? (Torigen I know only needs 4-7 grams of a tumor, so it is “technically” possible to do with a very small sample and not huge excision, though I don’t know if this done in practice or would be advisable; I have a call in to ask about this.)

[skip99]

No real advice, but I have a horse here with a large, assumed to be internal melanoma along his windpipe (grey and has other melanomas). His owners have been searching high and low for Oncept and have not been able to locate any, supposedly supply is being routed to small animal practices. The price for the Oncept was around 4 or 5k and then 1k a year thereafter if it could be found. We had him scoped for peace of mind and it is not restricting his trachea although he has developed a roar. Their vets did not have confidence in Torigen and this horse’s mass is not in a great location to operate. The plan is to keep looking for Oncept.

I’ll be following along to see what others suggest.

[Simkie]

I debulked my grey mare oh, I guess it was early spring 2023. It was an ugly recovery. The sutures didn’t hold. The swelling made her unable to poop. Her pain was poorly managed. We were never able to get her manure soft.

I would not do it again unless all other options had been explored and failed. Even then, I would be hard pressed.

I would also investigate how much internal melanoma exists before proceeding, if you choose to go this route. I put down my mare perhaps six months following, when it became clear she had melanoma in both eyeballs. It was very upsetting for her. I felt like I put her through the debulking for nothing, which sucked a lot.

My mare responded minimally to oncept. I’ve heard good things about torigen, and a former vet actually reached out despite moving across the country to suggest it for my mare.

Best of luck. Greys are so hard on this front. I’ll never own another.

[vxf111]

I just had to euthanize my sweet boarder because he developed melanomas in his anus and stopped being able to easily/comfortably pass manure. He went from being ok to needing to be euthanized in about a week. The vet said when they crop up there they tend to advance quickly and it probably means there are many internal ones as well. It was my first time dealing with this (I haven’t had grays and I won’t for this reason). I’m sorry. I wouldn’t do surgery in that area and if you don’t do the Oncept I would plan to let her go before it gets bad and she suffers.

[ThreeWishes]

No way would I touch those. Too significant.

[gradytb]

I put down my TB gelding in 2019 with melanomas like this, maybe a little worse. He’d had them starting in 2015-16-ish. They seemed to accelerate in growth and got oozy and stinky, at least the ones I could see. I assumed they were equally aggressive internally. I don’t have the kind of money it would take to do surgery, nor was he a good candidate for being stalled to recover, since my horses live out 24/7 and he would have lost his mind when the others went out and he couldn’t. He wasn’t happy and the other horses started to shun or pick on him, which was a complete reversal of behavior. I put him down while he still had some dignity and knew that I loved him.

[RosebudLaVie]

Hi there! I’m a veterinary oncologist in real life Before you make any decisions, I think it would be best to have your mare seen in person at Cornell. They’ll be much better able to give you an idea of outcome post-operatively once they’ve done their exam, and you can find out if there is any other testing they’d recommend to look for internal disease.
With regard to Oncept, yes, it is mostly found at small animal practices, but there are some of us who do farm calls to treat horses! So I would call around, and not assume that a small animal oncologist wouldn’t treat your horse, because some of us do! Some people will do Oncept pre-op to see if the tumors will respond; it’s an immunotherapy, so not all animals will mount an immune response, and some won’t mount enough of an immune response to clinically reduce disease. It wouldn’t be wrong to try that route, but Oncept is typically better in scenarios with minimal disease (ie. post-op); I do know some people who have seen responses with bigger tumors, though, so it’s not contraindicated, and it’s a very well-tolerated therapeutic.
I personally haven’t used Torigen, so I can’t speak much to it.
Good luck with your mare <3

[4horses]

Melanoma can go anywhere. I know someone who’s horse had tumors in his mouth. I have a client I clip horses for and that horse has multiple tumors all over. My concern would be that it is internal as well. However, that may not be the case.

[Demerara_Stables]

I have a client horse at my house who had these exact melanomas (and some in her mouth) removed last December via laser. The surgery was quick but being gray of course she bled a lot. I kept her on banamine per the surgeon’s recommendation for almost a week to make sure she was not uncomfortable passing manure. There were no sutures on the anus, only a couple of sutures on her mouth. Full recovery (meaning all of the skin grew back) was a few months but there was a meaningful recovery at about 6 weeks where there was no raw flesh anymore. I can DM you the nasty photos if you’d like. To be completely honest, I was totally horrified by what it looked like, but the surgeon did a great job of preparing me and told me I would be horrified for a while.

The mare has been on oncept for a few years, on a quarterly schedule due to a melanoma near her lymph node growing, becoming necrotic, and bringing on a nasty infection in December 2022. The quarterly schedule has kept everything from growing substantially.

The surgeon highly recommended removing the melanomas on the anus, in fact, we had only planned on doing the ones on her mouth because they were affecting her chewing and causing choke. He said he always does the ones on the anus if he can because they almost always grow to a size where they prevent the horse from passing manure.

I would 100% do this surgery again given my experience. I could not tell you what the cost was because it was a client horse and she paid the clinic directly. But if you are interested in spending the money, I think the laser specifically was a great option. Hopefully Cornell can offer that.

Can I ask why the horse has to be hauled to Cornell for the oncept? My vet comes out and does it at the farm.

[NaturallyHappy]

I sent you a pm.

[MaiTai]

Thank you so much for responding @ Simkie, and I’m so sorry to hear about your mare <3. That is exactly the type of situation that I am worried about. I appreciate you letting me know your story.

[MaiTai]

Thank you so much for letting me know, and I’m so sorry to hear about your boarder! <3

That quick progression is one of my big concerns; she seems completely unbothered at the moment, but the location just seems so fraught with potential complication.

I appreciate you taking the time to respond!

[MaiTai]

Thank you for sharing your experiences with this. This is my first grey (and I adore her) but damn, I really hate these melanomas. I’m sorry to hear about your gelding; thoroughbreds are the best, and it sounds like he was very well loved.

[MaiTai]

Thank you so, so much for responding! This is all incredibly helpful regarding the (potential) efficacy of Oncept as well as the suggestion for having her evaluated. I think I just got a little panicked when I saw/read the potential surgical outcomes, but you’re right that so much of this is speculative without an actual examination. My primary veterrnarian is coming out next week for Fall teeth, so I’m going to talk more with her then and will get the consult at Cornell set up.

It’s also really good to know that small animal vets may be willing to travel. I’m really hoping to avoid having to trailer her that far. Do you know in NY if the veterinarian administering the concept needs to be a boarded oncologist or internal medicine specialist, or could a primary (small animal or equine) veterinarian do it? There is a small animal oncologist within about 45 minutes of the farm, so I am going to contact the clinic to see if they might be willing to administer it (or I’d trailer the horse to the parking lot if need be!) but am just curious what the actual regulations are.

Thank you again!

[MaiTai]

Thank you for sharing your experience with this --that is encouraging to hear that the horse recovered well!! I’d definitely be interested in seeing the photos in a PM if you wouldn’t mind sending; that would be really helpful to just have a sense of what this might look like.

The growths causing eventual inability to defecate is one of my major, major concerns with her, but I’m also super anxious about putting her through something painful and protracted if there’s no “need.” (I wish I just knew how fast the darn things would grow! I’m a bit of an over thinker!!)

Really good to know about the laser, too. I’ll have to Cornell about that – she actually hasn’t even been viewed by the veterinarians there yet (this is all just virtual consult at the moment) but I’ll definitely bring it up. I think that my plan will be to trailer her there for an examination/consultation just so I can make a more informed decision about her particular situation, either way.

Re: the Oncept at Cornell: my primary veterinarian said that the vaccine would need to be administered in clinic, which I assumed meant Cornell. But, now that you ask that, I think I just made a leap of logic in my mind! We do have other clinics/hospitals closer to us than Cornell, but those equine clinics do not have boarded oncologists there–but perhaps we don’t need one? At any rate, thanks to this comment and @RosebudLaVie’s comment, you’ve given me the push I need to look for other options about having it down on farm or at the very least more locally; I really don’t want to be hauling to Ithaca and back across the state in the middle off winter if I don’t have to, and I’d like to spare her the stress.

[Simkie]

@MaiTai

It’s also really good to know that small animal vets may be willing to travel. I’m really hoping to avoid having to trailer her that far. Do you know in NY if the veterinarian administering the concept needs to be a boarded oncologist or internal medicine specialist, or could a primary (small animal or equine) veterinarian do it?

I’m in CT, and had zero issues with oncept being administered by my regular large animal veterinarian on the farm. I didn’t have to haul in, it didn’t need to be administered by a boarded oncologist, or by a small animal vet.

My large animal vet sourced it from the local VCA.

[gradytb]

I’ve had 2 greys and probably wouldn’t get another one, other things being equal between two horses. Which they never are! Lots of good advice here and hopefully it can be treated well enough to keep her another year or so.

[vxf111]

It was so sad, he was an absolute doll

[MaiTai]

This is really good to know, and something I’m going to bring up to my primary vet. I read that there’s some particular type of injector that they have to use? I would even be happy to buy that, etc. for the vet if she’d be willing to do it – I just really want to avoid having to travel that often (especially since I don’t have my own trailer right now).

[Simkie]

Yep, there is a special injector. It’s also important that the injector be kept against the skin after the click for a couple seconds. Helpful to discuss with the vet at the appointment, just to confirm everyone is on the same page (and so you don’t spend a grand dosing the air.)

Have your vet call Fairfield Equine in Newtown, CT with questions. I would also expect Rhinebeck Equine to do this, if you’re in their range.