This is an archived Horseadvice.com Discussion. The parent article and menus are available on the navigation menu below:
HorseAdvice.com » Treatments and Medications for Horses » Reproductive Drugs » Regumate® & Progesterone »
  Discussion on Regumate - UK member question
Author Message
New Member:
Saswain

Posted on Thursday, Feb 13, 2003 - 6:24 am:

My 5 yr old mare started mounting the other mares in her field in December last year. She corned one horse and mounted her over and over again until they were separated. The ovaries were normal or examination and on the ultrasound in December. Hormone tests (progesterone and testosterone)in December and end of January normal. Started on Regumate in January. I have turned her out with the same horse for one week and there have been no problems. My vet is suggesting that I leave her on Regumate until October and have her re-scanned then. My horse is kept on a big livery yard so it is a very difficult situation re: other liveries not being happy with my horse turned out with their horses. My questions are:

1) What are the side effects of long-term use of Regumate?
2) When would be a sensible time to re-examine her? I assume she could still have a GCT from reading your articles (which are excellent)
3) When would be the best time to try taking her off of the Regumate i.e., Spring, Summer?
4)Would you recommend testing inhibin levels? (Not sure if it is available in the UK)
Member:
Tonijo

Posted on Thursday, Feb 13, 2003 - 8:00 pm:

I just emailed you and forgot to ask........whats regumate? How does it work? Please be careful she doesnt continue mounting as my mare did the same and now has a medial collateral tear and torn meniscus in her hind limb(stifle area) from falling back a few too many times. I dont believe its a good prognosis and Im holding on to every last hope that shell beable to be ridden again(for pleasure).
Moderator:
DrO

Posted on Friday, Feb 14, 2003 - 6:39 am:

Hello DrS,
1) Surprisingly there are no published studies of long term use of Regumate (altrenogest). However we have several members who have reported using the drug over a whole reproductive season and through out a whole pregnancy without ill effects. Some have conjectured that this may promote an increase incidence of metritis, but there are no such reports.

2) I would reexamine sooner than has been recommended. These tumors appear to be somewhat FSH/LH responsive so some become larger in the reproductive season. I would check her in the middle of the season and check her several times over a month.

3) The problem with Regumate is it might make determination of which ovary is abnormal more difficult and the results of hormonal assays a little less certain. It is a variable that is not controlled for in what we know about diagnosing this disease. It has been my experience that GCT are not frequently Regumate responsive.

4) Yes I would. It continues to be the most reliable indicator. There has been some research into inhibin at both Edinburgh and Oxford so possible contacting them will help:
Equine Vet J 2002 Mar;34(2):203-6
Detection of high circulating concentrations of inhibin pro- and -alphaC immunoreactivity in mares with granulosa-theca cell tumours.
Watson ED, Heald M, Leask R, Groome NP, Riley SC.
Department of Veterinary Clinical Studies, University of Edinburgh and School of Biological and Molecular Sciences, Oxford Brookes University, Oxford, UK.

Recently it has suggested that determination of alpha-inhibin using RIA appeared to be a more reliable indicator of the presence of a GCT than specific measurement of alphabetaA-inhibin using IRMA:

Theriogenology 2002 Apr 15;57(7):1885-95
Inhibin concentrations in mares with granulosa cell tumors.

Bailey MT, Troedsson MH, Wheato JE.

Department of Bioengineering, Clemson University, SC 29634, USA.

The hormone-producing equine granulosa cell tumor (GCT) may secrete high levels of inhibin. Measurement of inhibin concentrations may be useful in the diagnosis and conformation of mares with GCT. Inhibin may be measured using RIA, which recognizes dimeric alphabetaA-inhibin as well as the monomeric (free) inhibin alpha-subunit, or using a two-site immunoradiometric assay (IRMA) specific for alphabetaA-inhibin. The objective of this study was to examine concurrent relationships among alpha-inhibin (as measured using RIA), alphabetaA-inhibin (as measured using IRMA), and other hormones (testosterone, estradiol, LH, FSH) in mares with GCT. Hormone concentrations were measured in single serum or plasma samples obtained from 22 mares with GCT and from 31 normal cycling mares. One GCT mare had blood samples collected at 12-h intervals for 21 days, and at 15-min intervals for two 6-h periods during that time. Results showed that in GCT mares alpha-inhibin was increased to a greater extent, was more uniformly elevated, and had a less variable secretory pattern than did alphabetaA-inhibin. Concentrations of alpha-inhibin and tumor mass were positively correlated (P < 0.01). Concentrations of LH were higher (P < 0.02) in GCT mares than control mares and were positively associated with testosterone concentrations (P = 0.05). Concentrations of FSH tended to be lower in GCT than control mares and were inversely related with alphabetaA-inhibin in GCT mares. Testosterone and estradiol concentrations were variable. It was concluded that immunoreactive alpha-inhibin reflected detection of both alphabetaA-inhibin and free a-subunit. Free alpha-subunit was evidently secreted at a relatively steady rate dependent upon mass of the GCT, whereas secretion of alphabetaA-inhibin was more responsive to FSH regulation. Determination of alpha-inhibin using RIA appeared to be a more reliable indicator of the presence of a GCT than specific measurement of alphabetaA-inhibin using IRMA.

Toni for more information on Regumate see the article associated with this forum. Just click on the link Progesterone and Regumate in the navigation bar at the top of this page.
DrO
Member:
Saswain

Posted on Friday, Feb 14, 2003 - 9:40 am:

Thank you very much for the information. I have spoke to my vet who recommends that we take her off of the Regumate in a few months time, plus have regular check-ups.

At the same time as the behavioural problems in the field started my horse also lost some the sight in one eye (delay blink response on menace test, pupillary response significantly slower etc) so we are both keeping our options open with respect to whether the problem may be neurological in origin. (All haematology/ biochemistry normal and no evidence of uveitis etc).

Thank you again for your excellent service
Member:
Cara2

Posted on Friday, Feb 14, 2003 - 12:00 pm:

Hi Sharon,

I'm sorry to hear that you are having these problems with your young mare. I do hope it doesn't turn out to be neurological but there is certainly something going on if her eye is being affected. How did she do with coordination tests if you did them? This is just an observation but my mare's paddock friend was recently diagnosed with Cushings and I've noticed that she has shown behaviour more like a stallion than previously around my mare - she hasn't mounted her but they haven't been out together as mine has been on box rest lately, but she does grunt and squeal like a stallion around an in-season mare when I bring mine over. I read recently that cortisol is a male hormone (have I got that right Dr O ?)and this is probably the reason.

By the way, did you know you can use pig Regumate safely with horses? It costs a fraction of the price so not many vets tell us about it!!

Good luck

Helen
Member:
Saswain

Posted on Monday, Feb 17, 2003 - 5:02 am:

Thank Helen for your post. My horse was tested for Cushing's and it was negative (she is only 5 so it was/is unlikely). I am using Pig Regumate but it is still £60 for 5/ 6 weeks. I did wonder if a pig farmer pays that much, but the vet I spoke to was a bit defensive when I mentioned it.
Home Page | Top of Page | Join Us!
Horseadvice.com is a BBB Accredited Business. Click for the BBB Business Review of this Horse Training in Stokesdale NC