Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. II

THE EMBRYONIC MORTALITY IN THE MARE

R .HOPPE
Dpt. of Obstetrics a. Pathology of Reproduction,
Faculty of Veterinary Medicine, Warsaw, Poland

The embryonic mortality appears in mares often; for
lack of experimental works only the clinical observa-
tions in breeding animals bring some information about
this subject. It was known since a long time, that in-
fections of the genital tract, especially by beta-hemo-
lytic streptococeci, can cause the death of the embryo
in the mare. Also the hereditary predisposition comes
into a count. As the e.m. appears mostly in nursing
mares, chlefly in these, which conceived during foal
heat, some authors suggest, that lactation might favour
embryonic resorption in mares /2/. The periodical in-
hibition of oestrus cycles after mating alone is not a
sufficient evidence of e.m.; it appears often in nur-
sing mares unmated in foal heat and in young mares,
mated for the first time. The repeated examination du-
ring the first 2-3 months of pregnancy gives the most
complete clinical picture, but the single examination
in this period permits also to reveal the ®mbryonic
death, 1f the state of genital tract will characterise
a much earlier pregnancy, than the date of the mating
indicates.

MATERIALS AND METHCDS . During the years 1948-1968, in
the course of about 3000 examinations for early pre-
gnancy in mares, two different clinical pictures, cha-
racteristic for the e.d. were found. The systematic
observations were made during 7 years in a Thoroughbred
stud of 45 mares, in which the service period begun in
the middle of February. All served mares were examined
rectally in the first days of April and of May as well
as 1in September. In the spring some additional examina=-
tions were performed. If the unsufficlent closing of the
vulva was suspected, the vaginoscopy was performed and
the cervical mucus samples were taken. If the death of
embryo was out of question, the uterus was washed out
with warm physiological solution.

RESULTS. As known, after the period of 3 weeks of pre=
gnancy 1n the mare a characteristic state of tension of
the uterus appears. The uterus horns, in consequence of
the contraction of the muscular layer, get more narrow
and sharp towards their ends, begin nearly in the trans-
verse diameter; their walls are thick and more compact.
This state lasts to the end of the second month of

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