Pharmacological manipulation Flashcards
reasons to manipulate estrous cycle
- improve reproductive efficiency
- assisted/advanced reproductive techniques
- improve management convenience/efficiency
- management of undesirable behavior
basic approaches to manipulation (6)
- mimic CL by administering progesterone
- lyse CL by administering PGF2a
- induce ovulation of mature follicle by causing LH surge
- prevent cyclicity by suppressing hypothalamo-pituitary acis
- induce cyclicity in anestrus animal
- increase ovulation rate by administering FSH
mimic the CL in cattle
- menengesterol acetate (MGA): given to feedlot heifers to prevent pregnancy orally, fertility at first cycle after discontinuation usually poor
- synchro-mate b: ear implant and injection –> estradiol supposed to be luteolytic –> most in heat within 4 days of removal (give PGF2a on day of implant removal)
- CIDR-B: controlled internal drug release –> leave in, give prostaglandin on last day, estrus 1-3d after removal
- PRID: progesterone releasing intravaginal device
mimic the CL in sheep/goats
- MGA
- syncro-mate
- intravaginal devices (progesterone sponges, intravaginal plastic devices)
- feed additives and sponges are off-label in US
mimic the CL in horses
- regumate: progestagen given orally or on feed once a day –> widely used in breeding management and to keep performance mares from showing estrus
- injectable progesterone
mimic the CL in bitches
- pyometra is always a risk
- megesterol acetate: given orally in proestrus to stop entering heat or in anestrus to delay next heat
how to lyse the CL
- animal must be cycling, CL must be at responsive state of development
- PGF2a and its analogs
- 2 injections often given since only 60% respond to first
lyse the CL in cattle
- lutalyse or estrumate
- 2 doses
- inseminated at observation of estrus or after some number of hours multiple times
lyse the CL in sheep/goats
- lutalyse, estumate
- 2 doses
lyse the CL in horses
- lutalyse or estrumate
- mare will get colicky and sweat for an hour
- will see heat in 3-5d
- 2 doses
lyse the CL in sows
- CL isn’t sensitive until 12 post-ovulation
- only used in combination with something that lengthens luteal phase or provides an artificial CL
- lutalyse
how to induce ovulation
- supply GnRH or an analog
- use the animal’s own LH or use HCG that has long-lasting LH activity
induction of ovulation in cows
- cystorelin and factrel
- both gonadotropins
- also treat follicular cysts
induction of ovulation in horse
- HCG when in estrus
- commercial “natural” GnRH preparations aren’t reliable
- implants are off the market
- injectable products available
induction of ovulation in cat
-HCG on day 1 or 2 of estrus
GhRH super agonists
- used to stabilize cycles before attempting superovulation
- smooth out menopause
- down-regulate pituitary responses to GnRH but first get a surge of gonadotropin output and ovarian stimulation
- can cause anestrus after a surge of gonatropin output and ovarian stimulation
GnRH antagonists
- gradually replacing GnRH super agonists
- compete with GnRH for receptors at the pituitary
- no initial burst of activity
mibolerone drops
- bitches
- anabolic steroid –> supplies feedback inhibition of hypothalamus (suppresses GnRH)
induction of cyclicity in the queen
- GnRH until estrus
- FSH then HCG to cause ovulation
induction of cyclicity in the bitch
- dopamine agonists induce estrus, shorten diestrus
- GnRH super agonists induce fertile estrus before down-regulation
superovulation
- higher doses of FSH given
- started mid-diestrus, injections daily
- dose of prostaglandin given
- ovulate more rapidly than ones not super-ovulated
melatonin implants or in feed
induce out of season cyclicity in sheep/goats
vaccination against androstenedione
- fertagyl (sheep)
- decreases estradiol production, thus decrease inhibition of GnRH and gonadotropins
- increase ovulation rate
