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64 Cards in this Set
- Front
- Back
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Breeding season
-define |
-period of sexual competence
-time from the first to the last ovulation of the year |
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Equine
-natural breeding season |
April -October/December
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Natural Breeding season
-influence |
-photoperiod
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Artificial Breeding Season
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February-June
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Reason to hasten ovulation in equine
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-January 1st is the official birth date
-Early foals are more mature at sales or shows |
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When is normal anestrus?
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winter
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When manipulating the equine estrus cycle, why do you need to be ready to breed?
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-fall transition is moving forward
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Artificial lighting
-from when to when |
-December 1st until spring
*do not start later than Dec. 21st |
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Artificial lighting
-important components to successful program |
-14.5-16 hrs of light per day
-add light at the end of the day -100 lux per 12x12 stall (100 W incadescent or 40 W fluorescent) |
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Why does artificial lighting before Dec. 1st not provide an advantage?
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-need to be exposed to some short days in order for the long days to have an effect
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Why is it not beneficial to begin artificial lighting after Dec. 21st?
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-day is becoming longer anyway
-need about 2 months for the mare to begin cycling |
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Artificial lighting
-how long until ovulation |
-70 days from beginning of treatment
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Dopamine D2 Antagonists
-effect on alteration of equine pregnancy |
-increase prolactin secretion ---> inc. number of gonadotropin receptors in follicle --> follicles more responsive to LH and FSH
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Dopamine D2 Antagonist
-Drugs |
-Domperidone
****-Sulpiride |
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Dopamine D2 Antagonists
-how to administer |
-keep mares under 3 weeks before beginning treatment ---> give daily ----> transitional mares ovulate 39 days from the beginning of photostimulation
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Dopamine D2 Antagonists
-mares take how long to ovulate under natural photoperiod |
-15-85 days
*depends on ovarian activity and temperature |
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Dopamine antagonist
-indication for use |
-when light treatment is not initiated until January
*will induce ovulation by mid February |
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Progestagens
-requirements for use |
-late transition
-multiple follicles of >20 mm -estrous behavior for > 10 days |
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Progestagen
-labeled product |
-altrenogest
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Altrenogest
-administration |
-oral for 12-15 days
-ovulation 12-15 days after end of treatment |
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Progesterone-releasing intravaginal device
-administration |
-treatment for 10 days
-ovulation in 4-8 days after removal |
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A client calls on January 1st to start breeding in February. On ultrasound, most mares have follicles < 15 mm in diameter. How can this be accomplished?
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-Dopamine antagonists combined with artificial lighting
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Response to advancing the breeding season depends on
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-time of year
-ovarian activity |
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A mare presents in May for artificial insemination with a 38-mm ovarian follicle. Would you inseminate today, or wait until the follicle grows larger?
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-No correct answer
-if inseminated today and follicle ovulates --> cheapest cost to client -if inseminate today but ovulates 4 days later ---> cost to reinseminate (double) -if don't inseminate and ovulates 4 days later ---> cheapest cost to client -if don't inseminate but ovulates that night --> cost to re-cycle |
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Induction of ovulation
-indication |
-synchronize mating with ovulation
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Induction of ovulation
-important for |
-inseminating mares with cool/cold semen
-breeding mares susceptible to post-breeding endometritis -breeding mares to a heavily booked stallion |
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Needed to induce ovulation
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-exogenous or endogenous LH (spike)
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Size of follicle to be affected by LH
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> 35 mm
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hCG
-function -produced where |
-function = LH-like activity
produced by the human placenta and purified from pregnant lady urine |
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hCG
-ovulation how long after injection |
-36 hrs (80% of mares)
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hCG
-negative to use |
Refractoriness
-mares may become refractory after repeat injections due to the production of anti-hCG antibodies -old mares are more likely to become refractory |
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Approved drug for LH increase/ovulation induction
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-Deslorelin
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Deslorelin
-function |
-GnRH analogue
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Deslorelin
-ovulation occurs when |
-40 hrs after injection
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Deslorelin
-positive |
-no refractoriness
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Deslorelin
-negative |
-$$$$
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Inducing luteolysis
-purpose |
-shorten diestrus
-"Short cycle" |
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Induction of luteolysis
-indications |
-save time after missed ovulations
-accomodate mares to the stallions book -synchronize estrus -treat prolonged diestrus -induce pregnancy loss |
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Inducing luteolysis
-hormone |
-PGF2a
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PGF2a
-approved drug |
-Dinoprost (natural PGF2a)
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Dinoprost
-side effects |
-transient sweating
-colic |
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Dinoprost
-how to minimize side effects |
-microdose
-10x less drug administered in 2 doses 24 hrs apart |
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PGF2a with fewer side effects than Dinopros
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-Cloprostenol
*not labeled for horses |
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Conditions necessary to shorten diestrus
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-CL
-CL > 5 days |
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Inducing luteolysis with PGF2a (Dinoprost)
-how long until return to estrus and ovulation |
-estrus: 2-5 days
-ovulation: 7-10 days |
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When should PGF2a be given to cause luteolysis?
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-when the follicle is small/medium (> 30 mm)
-if a large follicle, the follicle may regress and a new follicular wave has to emerge before the mare will return to estrus -up to 15 days |
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PGF2a
-possible anti-luteogenic effect |
-multiple injections of PGF2a starting at ovulation, may prevent formation of a functional CL and shorten the time to the next ovulation
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Estrus synchronization
-why attempt |
-sync estrous with stallion availability
-breed a group of mares -sync embryo or oocyte recipients and donors |
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Ways to synchronize estrus
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-shorten luteal phase with PGF2a
-Prolongation of luteal phase with exogenous progestagens -Induce emergence of a follicular wave with follicular ablation (research setting) |
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PGF2a
-# of injections to sync 1 mare with breeding |
-1 injection
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PGF2a
-# of injections to sync groups of mares |
-2 injections 14 days apart
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PGF2a
-how to administer to synchronize a group of mares |
-2 injections 14 days aprat
after 1st injection most should be in estrus 2-4 days later -ovulate in 7-14 days *Wide range |
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Progestagens
-reason to use for synching |
-tighter synchrony of animals
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Progestagen
-function |
-suppresses LH but not FSH
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Progestagen
-administration |
-treat for 8-12 days
-administer PGF2a to lyse any CLs -estrus in 2-5 days -ovulation in 6-9 days |
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Indications for use of progestagens
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-estrus suppression
-preg maintenance |
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Ideal method for synchrony of ovulations
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-progesteron in oil + beta-estradiol
***Coumpeded drugs are illegal |
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Estrus suppression
-indicated in what animals |
-pain or colic associated with estrus
-estrus related behavior and performance problems (pissy mare syndrome) |
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Estrus suppression
-rule outs |
-urogenital discomfort
-submissive behavior -stallion-like behavior |
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Estrus suppression
-drug -effects |
Altrenogest
-suppressed for as long as administers -3 days to suppress -not always allowed |
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Prolonging Luteal Function
-methods |
Intrauterine marbles
-suppression for 90 days35 mm glass marble |
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Prolonging Uterine function
-oxytocin |
7-14 post ovulation
-suppressed estrus for 50 days |
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Immunocontraception
-meant for |
-wildlife
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Ovariectomy
-why may a mare still show signs of estrus |
-remove progesterone
-more sensitive to low estrogen conc. -examine behavior during winter estrus |
