This is a little different from the mare not coming in after foaling her 1st This mare had a foal on her side last year when hse was bred-showed heat awesome took to the stud etc. Now this year-foaled April 18-had her foal heat-and nothing. She has been at the stallion owners for 2 weeks and nothing. On Thursday I picked up 2 shots of lutalyse-to be given 24 hours apart-as he said the lutalyse did not seem as effective this year. The first shot warmed her up-the 2nd had her sweating-butt tucking etc. Now 2 days later...nothing. My other mare also received a shot on Thursday-in heat Friday night and was bred today-no problem. The only thing I suspect as being a contributing factor is that she is the alpha mare-has been shipped off the farm-is being kept by herself. Anyone with any ideas? She is coming home tomorrow and being switched with another mare who HAS been cycling regularely.
Lactational anestrus may cause mares to be cycling but not display to the stallion, or to shut down completely until after the foal is weaned.
If the first, then prostaglandin (Lutalyse) may cause the mare to come in to estrus if there is a functional CL present, but if there is not - as a result of her just having ovulated - then it will not work. In any event, it will not impact the mare's desire to display to the stallion and she may still be a silent estrus mare. Likewise, if the second option (shut down), there will not be a CL present and you can give her all of the prostaglandin you want, and she won't cycle! Take a look at the article about why prostaglandin may not work for more information.
Incidentally, there is no reason why Lutalyse would "not be as effective this year". It is not subject to annual variations.
Another point to be aware of is that there is no need to cause a mare to sweat following prostaglandin treatment - and if they do or don't means absolutely nothing as to the efficacy of the drug. The sweating is simply an unpleasant side effect that could be seen in a gelding if it were given prostaglandin. This unpleasant side effect can be avoided by giving a mare prostaglandin at a one-tenth dosage for two consecutive days. The return to estrus rate will be the same, but without side effects.
With respect to what to do to the mare now, I would encourage you to have a reproductive work-up performed by a veterinarian experienced in equine reproduction, and that should include an ultrasound evaluation of the ovaries and reproductive tract, and possibly a blood-progesterone assay to determine if she is in fact cycling or not.
It just seems weird that she would do it this year-she was bred on 2nd heat last year with foal at side and has been bred simularely for 2 years prior. And when she is in heat-it is strong normally. As it stands-she is being given the year off-put back under saddle and will be doing club shows with my son.
One can see variations in estrual responses from cycle to cycle and from stimulus to stimulus, never mind from year to year, so I don't consider it particularly surprising. Sometimes we see a tendency to the opposite of anthropomorphisation, with humans thinking that as we are dealing with animals, they will all display a uniform behaviour pattern, but that is far from the truth and external stimuli (or lack thereof) are certainly a factor that comes to bear, as well as personal attitudes.
One can take a mare that is in strong estrus, and tease her with one stallion and see no response, and yet move to a different stallion and have her raise her tail over her ears and "display" to the nth degree!
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