152
46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
(v)
Abortion predicted increased effort and month of breeding to establish
pregnancy, but not becoming pregnant or foaling.
EED was shown to predict all outcomes. Interestingly, EHV-1 infection in the
previous season was not detrimental to any of the measured reproductive
outcomes, such as cumulative pregnancies and the percentage of live foals born the
following season.
It revealed some interesting observations that reflected the complexity of the
interactions that probably occur between multiple risk factors that underlie the
establishment of pregnancy and subsequently pregnancy loss. For example, using our
model, a five year-old maiden mare that had suffered just one EED incident had a
significantly lower predicted probability of successfully foaling when she was
compared with a 15-year-old foaling mare that did not suffer EED. This example
showed how other factors, such as EED, can modify the likelihood of a mare
producing a viable foal.
Conclusions
In conclusion, development of a predictive model for important outcomes enhanced
the understanding of complex interactions and relative influences of various
reproductive variables.
Risk factors will help us to identify individual animals with a higher probability of not
producing a foal each year and additionally, in late pregnancy progress has been made
over recent years both in identifying mares that suffer from placentitis and
furthermore instigating treatment to support the delivery of a viable foal.
Identifying the causes of EED is a great challenge and we can speculate that a
significant proportion of cases of EED probably arise due to gross chromosomal
defects of the conceptus, however we have limited knowledge on their frequency.
Irrespective of the underlying cause, treatment for EED routinely used in practice is
progestin supplementation. This strategy however remains undefined as although a
low incidence of luteal insufficiency in early pregnancy has been reported, recently
altrenogest was reported to have a positive influence retarded conceptus
development in older (but not younger) mares with normal luteal function. Two
important questions remain: first, what are the major causes of pregnancy failure in
the well-managed Thoroughbred mare; and secondly, can failing pregnancies be
successfully rescued with therapeutic methods?
References
1. Allen, WR, Brown, L, Wright, M and Wilsher, S (2007) Reproductive efficiency of
Flatrace and National Hunt Thoroughbred mares and stallions in England. Equine
Veterinary Journal 39, 438-445
2. Bosh, KA, Powell, D, Neibergs, JS, Shelton, B and Zent, W (2009) Impact of
reproductive efficiency over time and mare financial value on economic returns
among Thoroughbred mares in central Kentucky. Equine Veterinary Journal 41,
889-894
3. De Mestre, A (2013) Reproductive failure in horses: identifying the problem.
Veterinary Record 172(2): 42-43
152