DRAWING on 32 years experience, reproductive expert Professor Pat McCue from Colorado State University delivered three presentations on breeding abnormalities in mares to the 18th Irish Equine Veterinary Conference, held in November.
OVARIAN ABNORMALITIES
A problematic condition in mares is Anovulatory Follicles, carrying an ovulation failure rate of 4-8%Persistent Anovulatory Follicles, failure rate about 15%Hemorrhagic/luteinized anovulatory follicles are of unknown causeSwirling blood inside follicle means mare has not ovulated and won’t either. Wait nine/10 days and give prostaglandinsPersistent corpus luteum (PCL) is very common in mares. The mare fails to return to estrus (heat).EndometrititisEnlarged ovaries can be a tumour and 40% of these mares will exhibit stallion-like behaviourWith a granulosa cell tumour, it is more common for these mares not to show heat. The opposite ovary is small and inactive. The other is big and enlarged. Up to 95% of granulosa cell tumours can be diagnosed with Anti-Mullerian Hormone (AMH).UTERINE ABNORMALITIES
Persistent Mating-Induced Endometritis (PMIE) – up to 15% of thoroughbred mares develop itNot usual in maiden mares – usually affects older maresIncreased risk using frozen semenMost older mares will have an inflammatory event – could have a strep bacteria in uterusFungal endometritis – up to 5% of infections are associated with fungi. Common ones are Candida (58%), Aspergillus (25%), and Mucor (12%). Recurrence rate is high. Re-culture as needed.OVIDUCTAL AND CERVICAL
ABNORMALITIES
Common problem in oviductal is a Parovarian Cyst – embryological in origin. Hard to diagnose and can be confused with follicle on ultrasound.Less common is tumours/masses/adhesionsBlockage, usually consisting of mucus, collagen and degenerated cells, can occlude (block) the oviductMay prevent embryo transport – these are problem mares with infertility of unknown causeTry at least two different sires first before trying to diagnose this problemCervix – failure of cervical relaxation is common in older maiden mares over 15 years or mares used extensively for embryo transfer. These can have ET burnout. Allow an ET mare to carry a foal to term every three to five years. Mares should have a foal by eight to 10 years ideally.FOALING PROBLEMS
ITALIAN veterinary surgeon Matteo Mereu, Equine Surgery Resident at the Curragh’s Anglesey Lodge Equine Clinic, delivered a presentation on Dealing with Dystocias.
Dystocia (difficult births) occurs in about 10% of foaling maresMaternal factors can include uterine torsion (twist), fracture injury, inadequate pelvic sizeThe most common cause of a foaling problem is malposture of the foalThere is three stages to foaling. Stage 1 can take about one hour and the mare will exhibit signs similar to colic. Stage 2 is short and explosive during which the foal is delivered. Stage 3 is the passing of the afterbirth membranes.Most mares will foal by themselves without any human aidPresentation, Position and Posture – the Three Ps – are most importantRecord-keeping should be done and should include age of mare; due date; is she a maiden mare; has she had a live foal to date?Warning signs of a possible problem if there is no progression of the delivery of the foal’s amniotic sac within 10 minutes of the mare breaking her watersFast veterinary intervention can make all the difference in these cases. Have your vet or clinic’s number to hand. If the mare is expected to have a problem, make arrangements to get her into the veterinary clinic ahead of her foaling date.Wrap the tail to keep it out of the way and to aid visualisation of what’s happening. Is there blood? Is there mucus or dry?In C-section cases, up to 91% of mares and 35% of foals survive it if there is fast intervention in a clinic settingThe most common cause of death in foaling mares is haemorrhageMares should be observed closely after foaling, even if there was no problems, as haemorrhage can occur in the days after foaling as well. Fast veterinary intervention is crucial in these cases.