+ : interest in the stallion, ears pricked forward, lifting tail
++: stationary winking
+++: passive urination (full stream or small amounts in spurts)
++++: posture or leaning of the mare into the stallion, not always expressed around
ovulation time.
All non-receptive signs of oestrus behaviour include: tail switching, moving around,
squealing, holding ears back, kicking, attacking the stallion etc.
TEASING MARES IS AN ART AND A LEARNING PROCESS FOR THE MARES!!
Although not well documented in the literature, it is possible that changing levels of
oestrogen and progesterone throughout the oestrous cycle may influence nonreproductive body systems, such as the musculoskeletal system, since such effects
have been observed in women throughout the menstrual cycle. (12) If oestrogen and
progesterone have different effects on the musculoskeletal system in mares, it is
plausible that a subtle lameness could be exacerbated at specific times during the
oestrous cycle. A team approach between veterinary specialists to examine these
problem mares could be very enriching. (13) Some mares show temporary
symptoms of irritability or pain during the periovulatory period such as:
1. Change of temperament and willingness when ridden
2. Sensitivity to weight and/or manipulation of the back by the saddle etc.
3. Clear colic-like symptoms of pain with increased sensitivity during trans
rectal palpation of the ovary. (12)
These mares can be helped by inducing ovulation with agents such as LH or GnRH
products to reduce the times of discomfort,
Methods to suppress oestrus in the mare.
Several methods are available today to suppress oestrus in the mare and can be
categorized in:
A. The administration of exogenous progesterone
B. Extending the duration of corpora luteal function
C. Suppressing of the ovarian follicul ar activity
D. Bilateral ovariectomy.
Each method has its advantages and disadvantages.
A.The administration of (exogenous) progesterone:
Its effect is expressed in extending the duration of corpora lutea function therefore
suppressing ovarian follicular activity. We could inseminate problem mares and let
them carry their pregnancy, but according to the ‘FEI code of conduct for the welfare
of the horse’, pregnant mares must not compete after their fourth month of
pregnancy. According to the Jockey Club rules there are no restrictions. In the US it
is up to the jurisdiction of each State.
• Progesterone
Daily IM administration of 100 mg progesterone in oil (0.2mg/kg) effectively
suppresses signs of oestrus in mares, but due to the inconvenience of daily dosing,
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
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