Gynaecological Examination of the Subfertile
Mare
T.A.E. Stout
Utrecht University, Department of Equine Sciences, Yalelaan 112,
3584 CM Utrecht.
Identification of the problem mare
Although there is no rigid division between the ‘normal’ and the ‘problem’
mare, mares that are likely to be difficult to get pregnant are not that common
(<15% of the total population) and often identifiable from their history.
Therefore, obtaining a systematic history of both the mare’s general health
and her past reproductive performance, and recording the details
appropriately, is of paramount importance. For example, age and status
(foaling, barren or maiden) both have highly significant effects on the
likelihood that a mare will become and remain pregnant. Mares that are
barren despite attempts to get them in foal during the previous season are
likely to prove difficult again and, in general, beyond 14 years of age the
reproductive system (especially the endometrium and oocytes) of a mare
begins to show signs of degeneration which makes it increasingly less likely
that they will successfully conceive and carry a foal to term. In addition, aged
maiden mares often have an elongated, fibrosed cervix that inhibits the
evacuation of fluid after mating and thus predisposes to post-mating
endometritis. Dystocia or retention of the placenta at the last foaling would be
good reasons to suspect inadequate uterine involution and to avoid breeding
at the foal heat, while a history of problems such as intra-uterine fluid
accumulation or treatment (especially repeated treatment) for specific uterine
pathogens identifies a mare as a potential problem. A mare should also be
regarded as ‘difficult’ if she fails to become pregnant after insemination (or
mating) with good semen at 3 normal oestrous cycles or if she shows an
irregular pattern of oestrous cyclicity. Such animals are candidates for further
investigation and more intensive monitoring and management at the time of
insemination.
General Physical Examination
In theory, a general physical examination should be performed on each
animal at its first presentation and, for example, fertility is likely to be lower in
mares that are emaciated, in poor general condition or suffering from
concurrent disease. Abnormality of the hair coat (e.g. long curly coat) may
also be an indication of pituitary pars intermedia dysfunction (PPID), which
can influence both cyclicity and resistance to infection; if PPID is suspected,
e.g. in an older mare that shows abnormally slow follicle development,
elevated basal ACTH evaluation is a fairly reliable first indicator of a problem
that may require further examination or treatment.
In general, to maximize the chances of establishing the cause of any
problems and to optimize the time for insemination in difficult mares it is
advisable to combine information from as many means of examination as
15-‐18
February
2016
East
London
Convention
Centre,
East
London,
South
Africa
87