Page 435 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

410 CHAPTER 2

VetBooks.ir 2.2

Fig. 2.2 Teasing of a
Thoroughbred mare by a
stallion prior to natural
covering. Note the
restrained mare with a nose
twitch and padded boots on
the hind feet. The stallion is
presented to the mare from
the side to minimise the
chances of being kicked.

The expression of teasing behaviour can be vari- Transrectal ultrasonographic
able and some mares may need to be ‘broken down’ examination
by the stallion, which involves the stallion stimu- Ultrasound can provide the following information:
lating the mare by, for example, nuzzling. Maiden
mares and mares with a foal at foot will often tease • Presence or absence of a CL (Figs. 2.3–2.5).
poorly due to fear and uncertainty. • Follicle size, shape and echogenicity.
Teasing is a major management method for • Presence of endometrial oedema (Fig. 2.6).
identifying mares in heat. It is important to note • Pathology such as uterine fluid (Fig. 2.7),
that teasing is a poor predictor of ovulation, but is endometrial cysts.
very useful in differentiating oestrus from dioes-
trus. Inadequate teasing can affect reproductive A follicle of around 20–30 mm in diameter usu-
performance on broodmare farms. The use of an ally accompanies early oestrus. There may also be
effective teasing programme allows mares to be uterine oedema present. Progressive enlargement of
presented to the veterinary surgeon for ultrasound the follicle to 40 mm or greater is associated with
examination at the appropriate time, and this min- impending ovulation.
imises veterinary fees and unnecessary handling
of the mares. Vaginoscopy
A speculum is passed into the vagina and a visual
Rectal palpation inspection of the anterior vagina and external cervi-
Transrectal palpation is commonly used to deter- cal os is made (Fig. 2.8). The vulva should be thor-
mine the stage of the cycle in the mare. Cervical oughly cleaned with a paper towel and water and
and uterine tone and follicular size and firmness are dried prior to introduction of the speculum. A pen
assessed. Uterine tone is prominent and the cervix is torch is necessary to visualise the cervix. During
closed (cigar-like) when there are high levels of cir- oestrus the cervix becomes increasingly hyperaemic,
culating progesterone. Uterine tone is soft and the oedematous and relaxed (pink to red, moist, swol-
cervix open and relaxed when there are high levels len and lying on the vaginal floor). In dioestrus the
of circulating oestrogen and low levels of proges- cervix becomes paler, dry, tightly closed and elevated
terone. The ovary will be enlarged with follicular off the vaginal floor. Manual examination of the cer-
development. vix can also be performed and the changes described
appreciated by careful palpation.