Not in Foal?

– What Now?

By Jamie Anderson, MA Physiol (Oxon)

Mare and FoalSo you’ve tried and failed to get your mare in foal this year. You’ve had repeated cycles, and for whatever reason she’s not in foal. Don’t get too downhearted! Read the following points and check if you have covered all these areas – if not, then you’ve probably got a good chance of getting her in foal next season; but you’ll have to make some changes!

Get a reproductive soundness examination

Has your mare been properly assessed for her breeding soundness? If not (or if any of the examinations listed below have not been performed), then we would recommend that you get a full soundness examination done before you start next breeding season. It really is a false economy not to.

Conformation – perineal conformation, to make sure the mare’s vulva forms a tight seal, and does not allow air inside (pneumovagina), and does not become contaminated with faecal matter; these mares will probably need to be stitched up after breeding (Caslick’s procedure).

Vaginal inspection – to check for abnormalities, and to visually and digitally inspect the cervix

Ultrasound – cysts, and any other abnormalities of the uterus should be mapped before breeding, as well as a general examination of the ovaries, and any follicular activity

Cytology & Culture – to check for infection (bacterial or fungal). Many AI centres, vets and studs offer a culture service, but do not perform cytology. One without the other is virtually worthless, as contamination of the culture swab can give a false positive, or infection can be missed by culture alone.

Biopsy – the biopsy consists of taking a small amount of tissue from the uterus (which is entirely painless for the mare), and having it assessed for signs of infection, damage, and/or age related changes. The biopsy will be graded I, IIa, IIb or III – with I being the healthiest, and III showing the mare has less than a 10% chance of carrying a pregnancy to term. There are plenty of treatment options for grades IIb & III.

How old is she?

If your mare is over 12 years old, did she have any problems with fluid in the uterus after covering? Was she treated correctly? Mares with “delayed uterine clearance” (DUC) require aggressive treatment with ecbolics (which make the uterus contract, to help expel fluid) like oxytocin or cabetocin. Injections every 6-12 hours are required in many instances (and even more regularly with some mares). Even if your mare has no known history of DUC, then she should probably be given precautionary oxytocin therapy.
Old maiden mares need additional treatment.

Is the stallion you are using fertile?

Does the stallion have proven fertility using fresh, chilled and/or frozen semen? Look for “per cycle” pregnancy rates, which will give you an indicator of how fertile the stallion is. Average for fresh should be 70-90% per cycle, for chilled should be 50-65% per cycle, and for frozen 30-60% per cycle. If the pregnancy rates are quoted overall for the season, ask the stud how many cycles it has taken each mare to get pregnant. If the stallion has poor fertility, or the staff sending out chilled or frozen semen are inexperienced, then your chances of success are greatly reduced! Make sure the semen is checked thoroughly prior to insemination.

Is the vet, stud or AI centre doing a good enough job?

Poor timing, poor preparation, poor insemination, and poor post-breeding management can all be causes of a failed pregnancy. Make sure you’ve done your research, and are using an experienced vet, stud or AI centre. Get personal recommendations, or go by experience. Don’t just go by the fact that they are self-proclaimed specialists, or have a certificate on the wall. Published pregnancy rates are also a useful indicator, but again look for “per cycle” pregnancy rates, not “overall” percentages – “99% pregnancy rate” is absolutely meaningless!

If you’re performing the procedure yourself, make sure you brush up on your techniques. Simple errors can cause drastic reductions in pregnancy rates.

Consider all the potential issues, including stallion-mare incompatibility

It is possible that there is some underlying problem which has been missed.

Repeated failures could be due to:

– Anestrus (lactational/true/behavioural)
– Chromosomal abnormalities
– Nymphomania
– Delayed uterine clearance
– Endometritis (infectious/non-infectious)
– Urovagina
– Pneumouterus
– Cervical abnormalities
– Ovarian tumours
– Uterine fibrosis
– Endometrial cysts
– Uterine sacculations
– Blocked oviducts
– Hormonal issues
– Reduced immune response
– Stallion-mare incompatibility

Many of these can be checked out for during a breeding soundness examination.

There is currently no known test for stallion-mare incompatibility. Essentially, it is believed that some mares have anti-sperm antibodies which are specific to a particular stallion (or group of stallions), and that they are therefore unable to conceive when inseminated with semen from particular stallions. It is very rare, and people often jump to this conclusion when they have not explored the other options. However, if you’ve ruled out everything else, and change stallions and the mare suddenly gets pregnant, then you can be fairly sure that stallion-mare incompatibility is the cause of repeated failures.

If you’ve had a bad season this year, don’t feel too downhearted. There are plenty of reasons why the mare might not have become pregnant, and hopefully if you follow this brief guide, you will have a more successful season next year!

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