Regmate not working - ideas?

[leheath]

Last year my 6yo mare was demonstrating some serious behavioral changes.They seemed cyclical so vet suggested oral Regumate trial. Worked beautiful and my mare returned to her happy self. I took her off Regumate for the winter as recommended by the vet.

This spring, she showed the same behavioral changes, so I put her back on Regumate and it worked very nicely for a few months. Then I started seeing occasional glimpses of the troublesome behavior reappearing. Discovered she wasn’t getting the full Regumate dose. Fixed that problem, but still saw troublesome behavior. Increased the dose from 10ml to 11ml/day about a month ago, but that produced no obvious effects.

Last weekend the dangerous behavior fully resurfaced so I called the vet. He performed a repro exam and ultrasound. Thankfully no tumors, but that was the good news. The “bad” news is that both ovaries are very active. They had over a dozen follicles >20mm in diameter on them and the largest was 48mm in diameter. Obviously, this is not expected for a mare on Regumate!

So, has anyone had a mare with this issue? Do you give more Regumate? Something else? Ideas on the cause of this problem?

[Simkie]

This was posted recently. Some mares just need more?

[leheath]

Thanks Simkie! Wow, that would sure get expensive quickly! I am wondering what causes basically over active ovaries? Can they have too much FSH and, if so, what causes that? Or perhaps I just got a “bad” bottle of Regumate?

[bugsynskeeter]

Chances are that the 10 cc dose was underdosing her. She might need 12-15 cc depending on weight.

[Critter]

Had similar issues with my mare…had a consult at the university. The repro specialist told me that the Regumate will only help to prevent the teasing/hussy mare behavior, but it won’t actually prevent them from forming follicles. My mare was getting multiple follicles of 40+ even on a fairly high dose. They considered it normal as the regumate suppresses them from going into heat, but doesn’t always stop follicle development.

[leheath]

@Critter well that’s interesting and definitely not my vet’s experience! He said you may occasionally see a follicle in a mare who is pregnant and expects likewise for mares on Regumate as it is supposed to mimic pregnancy. He would not expect multiple follicle >20mm in size.

My mare never displayed teasing or hussy behavior. Her issue was definitely behavior caused by pain related to her cycles and it definitely was clearly resolved by regumate for the last year until the last 2 months.

[TheHunterKid90]

Since I really hate even being in the same room as Regumate, mine are on injectable altrenogest. About 10cc every 6 days keeps mine from growing large follicles and ovulating.
it’s best started right after ovulation so I will either tease the mare or ultrasound and take note of the size and firmness of the follicles…you can give chorionic to induce ovulation and can combine if with factrol to soften a very firm follicle so it is able to ovulate. Once they ovulate you can start the altrenogest…its the same regime the broodmares are on that don’t produce high enough progesterone levels to maintain pregnancy on their own.

my vet has also done the synovex implants in their chests that slowly release hormone over a long period of time. They were made for cattle but also work very well in horses…although one implant procedure last several months, you also don’t know when it will stop working so you either need to keep up and do more before it “runs out” or just wait til mareish behavior comes back and then redo the implants.

[leheath]

I have no problem safely handling the Regument but, in contrast, I am needle phobic so the injectable version would not work for me! I am also surprised you don’t have injection site soreness from having to do them every 6 days. How do you find the cost compared to the liquid format?

[TheHunterKid90]

It is about $100 for a ten week bottle. And they never get sore because I would never inject in the same spot twice you can do neck on both sides and also the butt on either side of the tail

[S1969]

@leheath

This spring, she showed the same behavioral changes, so I put her back on Regumate and it worked very nicely for a few months. Then I started seeing occasional glimpses of the troublesome behavior reappearing. Discovered she wasn’t getting the full Regumate dose. Fixed that problem, but still saw troublesome behavior. Increased the dose from 10ml to 11ml/day about a month ago, but that produced no obvious effects.

Last weekend the dangerous behavior fully resurfaced so I called the vet. He performed a repro exam and ultrasound. Thankfully no tumors, but that was the good news. The “bad” news is that both ovaries are very active. They had over a dozen follicles >20mm in diameter on them and the largest was 48mm in diameter. Obviously, this is not expected for a mare on Regumate!

My novice guess from my own fertility journey is that this issue was caused by the underdosing - that there was still enough hormone in her system to start follicles growing but because of the Regumate she probably did not ovulate normally so now there are retained follicles (basically cysts). Because she’s still on drugs they can’t rupture because she’s not ovulating, but probably there is no way to make them just disappear either.

What did your vet recommend?

In theory it might work to take her off Regumate and let her get a normal cycle, and then put her back on - but not sure if it would work if you weren’t monitoring to see that the follicles actually rupture.

[leheath]

The underdosing was fixed long enough ago that it shouldn’t be still causing these issues (unless the bottle of Regumate, which was new at the time, was defective in some way). Vet is still contemplating the best “next step” but we have taken her off Regumate for at least 10 days (since it obviously isn’t doing what it’s supposed to). He drew blood at the same time as the ultrasound, but hadn’t decided what to test it for when he left (he is now out of town until Monday so hope to have more info then).

I agree, that it would be hard to tell what’s working and when if we don’t do another ultrasound to see if these follicles disappear and/or if more appear. If one is breeding, then you want a >48mm follicle, which should only last a day or so, so she was at the perfect breeding moment the day we did the ultrasound…unfortunately, that’s not my current goal!

[Simkie]

I am admittedly not terribly familiar, but is it possible that once the train gets going, so to speak, it takes a lot more hormone to stop it? So she was short shrifted early in the season, started cycling, and is now resistant to a “normal” dose?

It makes sense in my head, no idea if that’s the way it works IRL

But wisdom from Jurassic Park…life will find a way! :lol:

[Pico_Banana]

@Simkie

I am admittedly not terribly familiar, but is it possible that once the train gets going, so to speak, it takes a lot more hormone to stop it? So she was short shrifted early in the season, started cycling, and is now resistant to a “normal” dose?

It makes sense in my head, no idea if that’s the way it works IRL

But wisdom from Jurassic Park…life will find a way! :lol:

There’s some merit to this, I think. I recently started my mare on the 30 day injectable and my vet advised to wait until she was clearly out of heat to give the injection because otherwise there were so many hormones active that the Regumate simply would not be able to overcome it.

She’s only on her first dose but I am very happy so far. I gave it in her pectoral and plan to switch sides each month.

[TheHunterKid90]

@leheath

The underdosing was fixed long enough ago that it shouldn’t be still causing these issues (unless the bottle of Regumate, which was new at the time, was defective in some way). Vet is still contemplating the best “next step” but we have taken her off Regumate for at least 10 days (since it obviously isn’t doing what it’s supposed to). He drew blood at the same time as the ultrasound, but hadn’t decided what to test it for when he left (he is now out of town until Monday so hope to have more info then).

I agree, that it would be hard to tell what’s working and when if we don’t do another ultrasound to see if these follicles disappear and/or if more appear. If one is breeding, then you want a >48mm follicle, which should only last a day or so, so she was at the perfect breeding moment the day we did the ultrasound…unfortunately, that’s not my current goal!

Remember, if you’re ultrasounding your mare to make sure she has ovulated to start back on regumate, the follicle size is not near as important as texture…i have a few mares that ovulate 34’s and others that hold onto them til they are 60’s…you need to keep track of when the follicle softens and then you’ll know she will ovulate soon. Then note the size of the follicle when she is soft and you think she will ovulate so you know in the future about what size she ovulates off of and can compare it with texture

[leheath]

@Simkie

I am admittedly not terribly familiar, but is it possible that once the train gets going, so to speak, it takes a lot more hormone to stop it? So she was short shrifted early in the season, started cycling, and is now resistant to a “normal” dose?

It makes sense in my head, no idea if that’s the way it works IRL

But wisdom from Jurassic Park…life will find a way! :lol:

LOL, love the Jurassic Park reference! I think there might be something in your thought process. I will ask my vet about it. It might actually be why he suggested taking her off Regumate for 10 days, then we will consider trying again with a higher dose, or maybe just a new bottle.

[leheath]

After careful consideration and discussion with my vet, coaches, and the nearby teaching hospital, I will be spaying my mare next week. I have read mostly positive reviews if there are realistic expectations and the problems are specifically ovary-related (not just hormones), which I am pretty confident is the case with my horse. Positive, healing vibes/thoughts appreciated.