Our 17 year old Talisman Bey granddaughter had never been bred. On the first try, she slipped the pregnancy early when her progesterone level crashed (or vice versa...) . On the second try, with regumate, she has done fine and maintained her pregnancy for 5 months. The stallion is a hero, by the way, AI took both times.
My vet and info on the internet says to keep giving it until "either 5 months or 7 months". My question is - which? I cannot afford to learn the hard way again - but I don't want to give her the regumate just to make myself feel better.

This is our first experience with breeding a horse. I had not even HEARD of regumate until we lost the first pregnancy. I promise I will not mistake your advice for advice from my vet, but I want your input.

What do experienced breeders do? Do you vary it from horse to horse? Is 5 months typical? Thanks!!!
Sandra J in Virginia

You need to speak with your vet. Have him/her pull her progesterone levels to see if it is safe to take her off. Some mares need to stay on Regumate until the day they foal.

Same as above. I have a mare that stayed on Regumate until close to delivery.. 30 days I think. SHe was followed by the vet and progesterone levels followed. She slipped a baby the year before. Will do the same this year !! Always check with the vet !

YEP...talk to your vet

I would of course talk to your vet. Most of the time we leave them on till they foal or wean them off to around their due date.

Circulating progesterone levels drop after the secondary CL's regress, so blood progesterone level tests will not tell you anything. They are supposed to have low progesteron levels later on in pregnancy.

The general rule of thumb for Regumate is 120 days. That is the threshold after which the placenta maintains the pregnancy and progesterone plays less of a role.

That said, if I have a valuable pregnancy in a mare with either a bad history or one that is older than dirt (like my Sasaki daughter) I leave them on it til they foal. Anecdotal, probably, but it makes me feel better. :0)

ValleyVet.com typically has a good price; anyone else found a cheap source? My local vet supply store has proven to be hard to beat on prices, so I'm lucky there but Valley Vet has been good in the past.

Edited to add: It does depend somewhat why the mare is on regumate in the first place. The pregnancy initially depends on progesterone produced by the CL on the ovary. At around 35 days, endometrial cups form betweent the placenta and the uterus that produce progesterone and maintain pregnancy. So if the mare has slipped prior to 35 days in the past but otherwise biopsies normally and is clinically normal, Regumate to 35 days is probably all that is necessary. If the mare has lost the pregnancy later in gestation, it is likely due to placental failure (cups or fibrosis, endometritis, etc.) and she could benefit from being on Regumate longer. Old mares that have lost muscle tone (don't forget the uterus is a muscle, too) and might have cervical issues can certainly benefit from being on Regumate the duration of their pregnancy.

My equine vet says usually 45 days if the fetus looks good, and from other vets I have been told around 100 days. Depends on the mare, and what your vet says.

I got mine from Allivet Animal Health
www.allivet.com
(877) 500-9944
(877) 500-9950 Fax
I just looked up the prices, Allivet is $239, and Valleyvet is $244.95

Go with whatever your vet says, but if it were me with a 17 yo maiden, I think I'd spend the money to keep her on it the whole time, I've had two over the years that slipped at 7 months and it was heartbreaking. Giving her Regumate the whole time isn't going to hurt her at all and a lot of people do just that as an 'insurance policy' to make themselves feel better. It's a big investment of time and money, whatever increases your odds. With the ones who've slipped early previously, we draw progesterone levels at about 4 months and see where they're at and then decide. OTOH, my older TB gets it the whole time, regardless. BTW Regumate is a synthetic and the test only measures what the mare is making on her own, so it doesn't interfere. I think we send ours down to UC Davis and it's about $25, but I've heard of people being charged 3 or 4x that, you might want to check what lab your vet uses.

Thanks for this thread. It is a topic I have had some curiosity about myself....