I have a maiden mare that had one ovary removed in February (she had a tumour). I followed her cycles closely through this breeding season and she cycled quite normally for 3 cycles. Then on the 3rd cycle she haemorraged into the follicle rather than ovulating and now has not come back into season for over 3 months, despite 2 shots of PG. Does anyone have any experience with this problem? I have taken her home from the stud now empty and will hopefully try again next season. Is she likely do come back into season normally next spring or am I going to have problems with her forever?
Posted on Tuesday, February 06, 2001 - 12:27 pm:
What I believe you experienced was a not uncommon form of ovarian hematoma which is an anovulatory follicle, more commonly seen later in the breeding season, and therefore termed an "autumn follicle", although it's technical name is "hemorrhagic anovulatory follicle syndrome". In this situation, the forming follicle grows to a normal ovulatory diameter, but does not ovulate, but rather it fills with blood. Upon ultrasonic evaluation it will initially show a thickening of the wall suggestive of luteinization and impending ovulation. Subsequently it's size increases, often up to 10 cm, and initial u/s evaluation at that stage demonstrates free-floating echogenic spots in the otherwise anechoic fluid, that may swirl if the ovary is ballotted (tapped), indicating that it is still fluid. Once the growth of the follicle ceases, the "spots" will coalesce and apparently become fibrinous bands within the follicle, and gelatinous, no longer responding to ballottment, other than by a slight quiver. It is thought that this type of hemorrhagic follicle may be deficient in estrogen, and this could be partially to blame for it's inability to ovulate. These will usually regress and disappear over the next month or so, although some, as in your mare's case, will take a little longer.
The above would have taken place last fall. The subsequent period of anestrus that you have observed is also completely normal. Mares are "seasonally polyestrous" which means that they have regular estrous cycles for part of the year; and no estrous cycles at all for another portion of the year. This latter period occurs in winter and is nature's way of avoiding mares having foals arrive during bad weather. (Note that human intervention with barn lighting and feeding more than would occur in nature will interfere with this effect in some mares, who will then continue to show estrus year-round although those in winter may be anovulatory). As prostaglandin requires a functional Corpus Luteum (CL) to work; and as that CL is the product of an ovulation, if the mare is in winter anestrus and therefore not ovulating, the prostaglandin will not work.
I suspect that you will see your mare entering estrus within the next couple of months with no trouble.
Jos, What you described above is exactly what I am going through with an older mare now, except that it is now May, not the fall. She has been lutalysed twice and still shows no signs of cycling again. Ideas?
Posted on Tuesday, May 15, 2001 - 10:31 pm:
Generally "HAF" will resolve themselves. What did the ultrasound show? And did you have a progesterone assay performed? It might be worth doing both those things if you haven't done them already.
The u/s obviously will show ovarian structures, and the progesterone assay will identify the presence of an active CL - one that is responsive to PGF2a
We did the prog assay, and it showed zero, so no suprise that she did not respond. I am going to have a Cushings test done, just for peace of mind, although she shows no symptoms. I have the medicine to start a 21 day routine with GnRH and progesterone. I guess my confusion is, why did she shut down in the spring? The ultrasound showed her ovaries getting smaller, as if she things it is fall.
I just found this list via a search. I have a mare that has an ovarian hematoma, but it is causing extreme pain and colic (she also had a fever of 104 for a while). Is this normal (she is at New Bolton right now)?
Jos, I have a 5 yr TB mare who was identified with a 40cm hung (diastral sp) follicle after a series of testing to identify a pain issue. The lutalys shot was successful, she cycled regularly for 2 mos and then 3 months later the pain issue again and no cycle. This time two follicles over 40cm one on each ovary. Lutalyse solved the pain issue again for only 4 months. I gave a shot last week without an ultrasound based once again on behavior. She is much happier now but my horse chiropractor recommended breeding her to permanently solve the problem. If I do decide to breed her, what are the chances she will settle, and do you think it will solve the problem? Is there perhaps another solution?
Posted on Thursday, August 23, 2001 - 01:51 am:
A diestrus follicle is not uncommon in the mare - which is unique among mammals in that they can develop a follicle and ovulate during diestrus even in the face of high progesterone levels. More commonly though these mid-cycle follicles regress rather that ovulate.
I am surprised that Lutalyse (Prostaglandin) assists in resolving such a follicle as it acts upon the Corpus Luteum and not a follicle. Are you sure that what you are seeing is not ovarian pain associated with ovulation and that you are giving hCG to encourage earlier ovulation?
In either event I have to agree with your chiropractor in that breeding her is probably a sensible solution and in fact may result in a permanent change for the better. It is unlikely that anything that you are facing now in connection with large follicles will be a problem connected with her conceiving - in fact the presence of follicles is of course a good sign!
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