Page 439 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

414 CHAPTER 2

VetBooks.ir HISTORY vestibular sphincter temporarily relaxes to allow
entry of the stallion’s penis. Other mechanisms
It is essential to collect and record a full history of
the mare in general and specifically her reproductive (e.g. uterine contractions and immune-mediated
reactions) are thus also important in protecting the
performance. Details of the type of work the horse reproductive tract against infection.
has previously undertaken, or is undertaking if still It is very important to assess the vulval/ perineal
performing, should be noted along with any drugs conformation and to observe any vulval discharge
used or injuries incurred. Any history of abnormal (Figs. 2.13–2.15). Anatomical alignment of the
oestrous cycles while in training can be significant to perineal and pelvic conformation is important for
future breeding ability. The age of a mare may influ- breeding soundness and should be assessed from the
ence her breeding efficiency (i.e. young mares may back and side. Placing a finger horizontally on the
be sexually immature or abnormally cycling). Older posterior tip of the bony pelvic brim adjacent to
mares may have declining fertility from 12 years of the vulval lips allows the clinician to assess where
age onwards due to previous reproductive injuries or the dorsal vulval commissure is in relation to the
wear and tear. A detailed reproductive history should bony pelvic brim and also the angle of the vulval
include: the number of foals bred (live or dead); the commissure. The integrity of the vulval lips needs
incidence of dystocia, retained fetal membranes, to be assessed and any injuries noted. Defective
abortions, early embryonic death; breeding history vulval conformation (VC) is related to a sunken
with note of previous fertility or infertility, twins anus and atrophy of the perineal body. It is more
and history of endometritis; sexual behaviour, espe- common in older, pluriparous mares that have had
cially the mare’s oestrous cycle; treatment history repeated foalings and in mares in poor body con-
including drugs used and surgery performed; and dition. The vulva is best evaluated during oestrus,
laboratory results. when it is most relaxed:
Knowledge of the fertility of the sires previously
used, as well as the current stallion, plus the method • VC good. Vulval lips are vertical. Lips are
to be used for insemination are important factors to closely apposed, making a good seal. Dorsal
assess. commissure is either below the bony brim or up
The general physical condition of the mare should to 2.5 cm above.
be appraised as poor condition or obesity can affect • VC fair. Vulval lips inclined up to 30° off the
fertility. Systemic illness such as Cushing’s disease vertical. The lips are apposed, making a good or
may affect the ability to conceive, while other condi- reasonable seal.
tions such as chronic laminitis, chronic lower respi- • VC poor. Vulval lips are inclined more than 30°
ratory tract disease or ventral hernias may affect the off the vertical. Poor or ineffective seal. More
mare’s ability to carry a foal to term safely. Poor diet than half of the vulval commissure is above the
and other management factors (e.g. stress) can sig- bony brim, with a sunken anus.
nificantly affect fertility rates.
Poor conformation will commonly lead to pneu-
REPRODUCTIVE EXAMINATION movagina, urovagina, accumulation of intrauterine
fluid and endometritis. Foamy, frothy exudate may
External genitalia be detected in the vaginal cavity.
There are three main anatomical barriers that main- The lips of the vulva should be parted to deter-
tain the integrity of the caudal reproductive tract: mine the integrity of the vestibulovaginal sphincter
the vulva including its labia, constrictor muscles (no air should enter the cranial vagina) and assess the
and perineal body; the vestibular sphincter includ- colour and moisture of the lining of the vestibule.
ing the constrictor muscles of the vestibule; and the The integrity of the perineal body is assessed by
cervix. These barriers block the aspiration of air and placing one finger in the rectum and the thumb in
contaminants into the reproductive tract. During the vestibule. At least 3 cm of muscular tissue should
oestrus the cervix is relaxed and during coitus the be present between the two digits.