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  Discussion on Mare behaving like a stallion.
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Member:
Banthony

Posted on Thursday, May 18, 2006 - 12:05 pm:

Dr. Oglesby and anyone else -I would like to know if you have ever run into this before.

We have a client mare who is a 10yr old thoroughbred. She had a foal last year and stopped teasing in even though she was developing follicles. We did manage to get her bred twice, but she didn't settle.

We put her under lights in January this year and she cycled once and then did not come back in. We gave her prostin, she cycled normally, we got one cover, and she got in foal.

She had twins pinched at 16 days and was started on Regumate. Shortly after being checked 30 days in foal she started getting stallion - like behavior. This has gotten progressively worse. I of course was thinking GCT.

She was ultrasounded at 55 days. The pregnancy was normal and both ovaries appeared normal.

She now aggressively teases the mares and even smells manure in the pasture. She has gotten a lot of kicks from aggressively approaching mares.

We had her checked again 2 days ago. The ultrasound for the ovaries was normal. Blood was drawn and sent to a specialty lab in KY. The results came back today - everything absolutely normal. Our vet says the embryo is secreting testosterone and that is causing the behavior.

This usually very sweet mare is getting so beaten up. We don't have a way to put her by herself. All our pastures are segregated and we only have one mare pasture.

Will this resolve at some point or will she be like this until she foals?

Help!
Member:
Christos

Posted on Thursday, May 18, 2006 - 4:36 pm:

Yes, Linda, I have seen this once whith a generally very troublesome mare (a hormonal mess is what I think she was). This behaviour started by the second month of pregnancy and lasted for two months or so.
It was not such a problem as the other horses simply run away from her. She was already the boss, so no conflict there.
I do not know what caused this behaviour. It seems that a hormone related attitude problem was running in that family.
Moderator:
DrO

Posted on Friday, May 19, 2006 - 8:18 am:

I think the key here is you need to find a safe situation for his mare right now. If you have no place to put her on your farm she needs moving somewhere that she and her pasture mates are not at risk.

Unfortunately there are no tests that are 100% for diagnosing GCT so this remains a possibility. I am interested in what tests where run and what the results were including the normals for the lab. I have heard the foal's hormones theory before but I don't know of any proof of this. Without a firm diagnosis you are in uncharted waters so you must manage this day to day making adjustments based on what you see. Please keep us informed as to how this plays out.
DrO
Member:
Banthony

Posted on Friday, May 19, 2006 - 11:05 am:

Thanks to you both for replying. I hope that the behavior stops at some point.

You are right, Dr. Oglesby, we will have to get her out of the mare pasture. Her pasture mates are unscathed, but she is getting beat up through no fault of her own.

I can try her with my old gelding or we may have to block off an area between pastures and put her by herself. She is a long time resident and we are quite attached to her so we will do what ever we need to do.

Here are the blood results:
Member:
Banthony

Posted on Friday, May 19, 2006 - 11:37 am:

I can't seem to attach the results so I'll just type them.

Result Units Normal Range

T4 Basal 18.50 ng/ml 9.0-26
Prog Basal 15.60 ng/ml n/a
Moderator:
DrO

Posted on Monday, May 22, 2006 - 6:29 am:

Thanks Linda, certainly the progesterone level makes GCT unlikely.
DrO
Member:
Dreamsox

Posted on Monday, May 22, 2006 - 7:43 pm:

HI Linda, interestingly I have a mare very similar to yours. She is in foal now, the ultrasound showed twins( one was pinched) at 16 days, and she is very stallion like right now. Even to the point of being quite dangerous to handle( she is a successful event horse of mine, born her on the farm) Both she and her mother have shown this behavior a week before foaling, but never the entire pregnancy. Im a bit worried. Any advice DrO????
Moderator:
DrO

Posted on Tuesday, May 23, 2006 - 8:15 am:

Regumate might decrease the aggressive behavior but it is a bit of a long shot and would not be my first choice. I would give you the same advice I gave Linda above: find a safe situation for your mare and in this situation, you. If you feel she is dangerous to be around, you need to find someone to put her with that is more comfortable with the behavior.

You too might check your mare for unusual hormone levels like that seen with GCT but as you can see from the posts above this is a phase some pregnant mares go through.
DrO
Member:
Banthony

Posted on Tuesday, May 23, 2006 - 9:34 am:

Dr. O - Your comment about the progesterone level being normal. She is being supplemented with progesterone. She has been on Regumate since the twins were pinched at 16 days. We were going to wean her off but when the behavior started the vet recommended we keep her on it.

In the last couple of weeks her behavior hasn't gotten worse at least.
Member:
Banthony

Posted on Tuesday, May 23, 2006 - 4:07 pm:

Terrie, the coincidence of twins being pinched is very interesting. Did you put her on Regumate after the pinch?

What breed is your mare?
Member:
Dreamsox

Posted on Tuesday, May 23, 2006 - 10:07 pm:

Linda, My mare is a 9yr old Swedish/thor. This will be her third foal, she is due in the end of June and is huge.Im hoping there is really only one baby. I did not put her on Regumate(its risky for us humans)I find even with gloves on and trying to be really careful, its hard to keep it from getting on my skin.( I had her one it when she was horseshowing) Her behavior is good right now because she is pretty miserably pregnant. When is your mare due??
Member:
Banthony

Posted on Wednesday, May 24, 2006 - 9:33 am:

Terrie, This mare is 90 days in foal. I think we are going to start weaning her off the Regumate by 100 days.

I know what you mean about Regumate. I hate handling it too. The vets here put mares on it if there is even a hint of a problem. So it seems we always have someone on it. There is a type of cap that you can screw the syringe right to - and with gloves it doesn't get on you if you are REALLY careful. But when you are in a hurry to get a million other things done that doesn't happen all the time.

Good luck with your mare. Hopefully she just has a really big, nice foal in her.

This mare isn't as bad the last week. She seems kind of depressed and stays off by herself most of the time. The only time she is acting like a stallion now is when we first turn her out after feeding.
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