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ANOVULATORY MARE PROTOCOLS:
INDUCTION OF OVULATION:
The most common cause of prolonged anovulation (greater than
six months) in mares is Cushing’s Syndrome. A Cushing’s Screen
(see BET Protocol) should be performed in these mares. If they
are positive, they will not respond to the following protocols
unless treated for Cushing.
Anovulatory mares have serum concentrations of progestagens that
are less than 1.0 ng/mL. A progestagens assay should be performed
before starting any protocol. Additional progestagen assays should be
performed following completion of the protocol to detect ovulations,
which may have occurred even though the mare did not show estrus.
These mares will respond to prostaglandin injections and exhibit normal
estrous cycle if TT4 levels are sufficient (i.e. greater than 12.0 ng/mL).
A Total T4 assay should be performed in all anovulatory mares or any
mare not exhibiting normal estrous cycles or ovarian follicular development.
Mares with TT4 concentrations below 12.0 ng/mL will not respond adequately
to the anovulatory protocols. Response will be significantly improved when
sufficient thyroxine is given orally to elevate TT4 concentrations between 14
and 20 ng/mL. The dosage should be titrated so that these concentrations are
present 24 hours following the dosage of thyroxine. This simply means that the
blood sample should be taken before the oral dose of thyroxine is administered
and not afterwards. Thyroxine need only be given once per day. Thyroxine
should be continued at least until 45-50 days of pregnancy. It is imperative to
monitor TT4 concentrations to insure that the proper amount of thyroxine is
being administered. Too much will cause weight loss and hyperexcitability, and
too little will be ineffective.
ANOVULATORY PROTOCOLS IN POST-FOALING OR TRANSITIONAL MARES
A. DEEP ANESTROUS MARES with FOLLICLES LESS THAN 10 mm
BioRelease™ Deslorelin + BioRelease™ P4 LA, for 10 days
Prescribe BioRelease™ Deslorelin 0.14 mg/mL + BioRelease™
P4 LA 182 mg/mL, 1 mL daily, IM, SID or BID. More rapid results may be
obtained with the BID administration although not critically studied as of yet.
Treat for 10 days only. Ovulation usually occurs by day 21 after the first injection.
Use BioRelease™ Deslorelin 1.5 mg and 2500 I.U. hCG when
follicle is 35 mm or greater.
B. LACTATIONAL ANESTROUS MARES with FOLLICLES 10 mm TO 25 mm
OR GREATER
Option 1:
BioRelease™ Deslorelin + BioRelease™ P4 LA for 10 days
Prescribe BioRelease™ Deslorelin 0.14 mg/mL + BioRelease™
P4 LA 182 mg/mL, 1 mL daily, SID or BID.
Option 2:
Combination of BioRelease™ Deslorelin and Regumate or
BioRelease™Altrenogest LA or BioRelease™ P4 LA (see below):
>>>>>>>>>>>>>>>>>>>>>>>OR
10 mL BioRelease™ P4 LA 150, IM, on day 5 only
>>>>>>>>>>>>>>>>>>>>>>>OR
1.5 mL BioRelease™ Altrenogest LA 150, IM, on day 5 only
C. LACTATIONAL ANESTROUS MARES with FOLLICLES EQUAL TO
or GREATER THAN 25 mm
BioRelease™ P4 LA 150, 750 mg (5 mL), IM, as a single injection
>>>>>>>>>>>>>>>>>>>>>>>OR
BioRelease™ P4 LA 300, 600 mg (2 mL), IM, as a single injection
>>>>>>>>>>>>>>>>>>>>>>>OR
BioRelease™ Altrenogest LA 150, 225 mg (1.5 mL), IM, as a single injection
D. TRANSITIONAL MARES with FOLLICLES GREATER OR EQUAL TO
15 mm (must have been under lights for 60 days)
BioRelease™ P4 LA 150, 750 mg (5 mL), IM, as a single injection
>>>>>>>>>>>>>>>>>>>>>>>OR
BioRelease™ P4 LA 300, 600 mg (2 mL), IM, as a single injection
>>>>>>>>>>>>>>>>>>>>>>>OR
BioRelease™ Altrenogest LA 150, 225 mg (1.5 mL), IM, as a single injection
>>>>>>>>>>>>>>>>>>>>>>>OR
BioRelease™ Deslorelin, 125μg (1 mL), IM, BID, until mare ovulates
GnRH + PROGESTERONE PROTOCOL FOR ANOVULATORY MARES
Total T4 (serum thyroxine) must be above 12 ng/mL and progesterone less
than 1.0 ng/mL for this protocol to work.
DAY 1
1 mg GnRH a.m., IM
1 mg GnRH p.m., IM |
DAYS 5 THROUGH 16,
administer 200 mg of
Progesterone/day, IM
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DAY 5
1 mg GnRH a.m., IM
1 mg GnRH p.m., IM |
DAY 11
1 mg GnRH a.m., IM
1 mg GnRH p.m., IM |
DAY 16
Last day of Progesterone Treatment |
Mares should be in heat by day 22. If not in heat by day 24, pull blood
for Progestagens assay. If Progestagens are greater than 1.0 ng/mL
give Prostaglandin.
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