Page 444 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.1 The female reproductive tr act 419

VetBooks.ir The endoscope needs to be capable of sufficient 2.21
insufflation and washing to allow the technique to
be carried out effectively. It is introduced into the
uterus using the same technique as for endome-
trial biopsy and the uterus is insufflated with about
1–2 litres of air or saline (Fig. 2.21). This technique
is useful in assessing and detecting endometrial cysts,
polyps, intraluminal adhesions, endometrial damage
and haemorrhagic foci as well as guiding specific site
endometrial biopsies. A complete examination of the
reproductive tract should be carried out before the
endoscopy, as the latter does cause some endometrial
damage. Fibreoptic examination is best carried out
in dioestrus due to difficulties in maintaining air
within the uterus during oestrus, when the cervix
is relaxed. Fig. 2.21 Hysteroscopic view of the uterine body
and separation into two horns of a normal mare.
Blood endocrine assays (Photo courtesy Tracey Chenier)
Blood samples for the measurement of hormone con-
centrations are a routine part of broodmare manage-
ment. Progesterone assays are helpful in detecting blood increase from day 35 of pregnancy and are
whether functional luteal tissue is present within the predominately secreted by the fetus and fetal mem-
ovary. They can aid in assessing mares during the branes. They are therefore often used as an indicator
transitional period for the first ovulation rather than of fetal viability in the mid-late term pregnant mare
repeatedly examining the mare by rectal ultrasound, (see p. 431).
and also guide when luteolytic drugs can be used.
Progesterone measurement during early pregnancy Karotyping
is useful to decide when endogenous progestagens Karyotype examinations can be performed on ani-
are insufficient (<12.7–15.9 nmol/l [4–5 ng/ml]) and mals suspected of having a chromosomal abnormal-
the need for supplementing with exogenous proge- ity. Heparinised blood samples are used to harvest
stagens (e.g. altrenogest). Testosterone and inhibin lymphocytes, on which chromosomal analysis is
blood levels can be assayed and they may be raised carried out. It is particularly indicated in mares that
in ovarian granulosa (thecal) cell tumours (GCTs) have never cycled, have infantile reproductive tracts
(see p. 482). Oestrone sulphate levels in the mare’s or fail to maintain a pregnancy.

MANIPULATION OF THE FEMALE REPRODUCTIVE CYCLE

ADVANCING THE ONSET OF (northern hemisphere) or 1st August (southern
SPRING TRANSITION hemisphere). Breeders will therefore strive for
early-in-the-year foals. Early seasonal cyclic abnor-
The transition of the mare from winter anoestrus mality wastes time, increases the workload of the
into the normal cyclicity of the breeding season stallion, especially later in the breeding season, and
usually occurs in early spring. This can present increases veterinary involvement and expenditure.
problems to the owner of the mare if it belongs to Breeders therefore request techniques that can
one of the breeds (i.e. Thoroughbred) that have advance the earliest date of mating in barren and
an artificial birthday for all foals of 1st January maiden mares.