Mare not in season

[No_Angel]

I took my mare to stud, she was covered and scanned not in foal, vet said there was a an egg about to be released and she would be in season soon.
She was given an injection before going to stud as she was late coming into season, a few weeks later she was given another injection to bring her in season ready for going to stud.
After she was scanned not in foal, she was left to come into season naturally so she could be covered again, but she did not come into season. She has shown no signs of being in season since coming home. I have been away for a week, but there are no signs she has been in season while I was away.
Could the injections have messed her season about? Or the weather?
She is usually very obvious when in season and it was unusual that she was late before going to stud.

[Rips]

Can't remember the name of it but its something that happens maiden mares after they've been covered that stops them showing signs that they are in season - it doesn't mean they aren't in season. Something to do with the Luteals or something, I'll see if I can find it again...

I don't know can the injections mess them around the same way, but last year one of YO's good breeding mares (who has always come into season and taken first time) had a late foal, so he decided to inject her to come in, it would have been around this time and she never took that year.

[Rips]

Oh its two different things I was reading about...

Persistent Luteal Activity in Non-Pregnant Mares

Persistence of luteal activity in the non-pregnant mare is a major cause of subfertility and is the main cause of anoestrus during the breeding season.� Traditionally, the term 'prolonged dioestrus' has been used to describe a condition where the function of the corpus luteum continues beyond its normal cyclical lifespan of 15/16 days, resulting in the maintenance of elevated circulating progesterone concentrations for longer than expected.

The term 'prolonged luteal activity' is now preferred.

Persistent luteal activity often arises from accessory ovulations that occur during the normal dioestrous period.� They occur in up to 20% of oestrous cycles in Thoroughbred mares (less frequently in ponies) and are not accompanied by oestrus; the cervix will remain pale in colour, dry and tightly closed.� If dioestrous ovulations occur late in the luteal phase they will be refractory (unaffected) to the effect of endogenous luteolysins, resulting in a persistent luteal phase.� These mares present great difficulty to the stud manager as they can be assumed incorrectly to be pregnant.


and


Absence of subsequent oestrous behaviour

The first is assessing the mare's behaviour by daily teasing from day 12 to 24 when pregnant mares should aggressively reject the male.� Teasing is a very important part of routine stud farm management and is an important asset to the veterinarian�s reproductive examinations.

����������� However, mares vary enormously in their display of signs of oestrus and to some extent this is influenced by the technique used to tease the mare.� Some mares will display oestrus signs readily, even to other mares or people.� Oestrus signs can be seen in some mares in dioestrus and late pregnancy occasionally even due to vulval irritation.� Other mares will not show oestrus signs at all.� In particular, mares that were bred for the first time (maiden mares) or mares with a foal at foot are likely candidates for failing to show oestrous behaviour.� Therefore, a significant number of mares either do not exhibit signs of oestrus, or are slow to show detectable signs using standard teasing methods despite the fact that they are in oestrus.� This is called silent oestrus.�

����������� The incidence of silent oestrus is thought to be approximately 6%; it is thought to have a higher incidence in maiden mares early in the breeding season and in mares with a young foal 'at foot'.� Other factors which affect oestrus behaviour include being at grass with very dominant mares, and stallion preferences.

����������� Mares that are in training and have been treated with anabolic steroids may be more likely to suffer from the condition due to 'androgenization'.

����������� Similarly, mares that are in a prolonged luteal phase will not show signs of oestrus.� The same is true for mares which undergo early embryonic death after day 15 and prolongation of the lifespan of the primary CL (pseudopregnancy type 1) or mares in which the foetus has died after establishment of the endometrial cups (approx. day 37; pseudopregnancy type 2).



They are a few causes in that last one, if you had her scanned late it could be possible that even the last one is the case?

Aw its a pity she didn't take for you :( Its quite late in the season now. I'd almost expect alot of mares to have stopped coming into season anyway. I also think the signs of season become less obvious as the summer somes to an end.

[Showjumper]

My friend sent her horse to stud back in April. She's just come back not in foal after many attempts and two scans. The vet thinks it's to do with the weather - she's an older mare and the vet doesn't think she wants to do the baby thing when she's not sure what to wear herself.