Equine Breeding Management and AI Flashcards
Breeding systems
- pasture
- hand
- artificial insemination (not allowed for Thoroughbreds)
Types of mares
- wet: foal at her side
- barren: open for at least one year
- maiden: never been bred before
When to breed?
- male factors
- female factors
- history
- palpation findings
- US findings
- teasing
- when ovulation is eminent
Tools
- teasing
- rectal palpation
- vaginal speculum exam
- ultrasound
- hormone assays
Teasing
Expose a mare to a stallion to gauge mare’s willingness
- +/- to score mare’s response
- allow time to gauge response
- mare with foal may not react predictably
Recorded findings
- cervix
- RO (right ovary)
- LO (left ovary)
- uterus
- fluid
- cysts (endometrial cysts)
Findings in mare in estrus
Large ovary (30-60 mm) that may be soft
- uterus lacks tone
- cervix difficult to palpate b/c its flaccid, open
- pink and edematous cervix that is open on speculum exam
Ultrasound findings
Follicle of 30 mm or larger
- ovulation occurs between 35-55 mm
- follicles grow at rate of 2-4 mm per day
Edema in the uterus
Wagon wheel look
- increases then disappears before ovulation
Endometrial edema is due to ______
Rise in estrogen at onset of estrus
- score 0-3
- 0 = no edema
- 1 = slight
- 2 = moderate
- 3 = heavy (pathologic)
Edema will progress and then regress ________
24-36 hours prior to ovulation
- useful in predicting ovulation
- 0, 1, 2, 2, 1, ovulation —> days 1-6 of estrus
Impending ovulatino
Follicle softens
- hyperechoic rim around follicle
- becomes pear shaped
When to order semen
- follicle is 35 mm
- endometrial edema is present
- follicle softening
- mare displays estrus
For best results, breed mare _____
12 hrs prior to ovulation to 6 hours post ovulation
Evaluate semen motility after ______
Warming
- 30% motility min
Need to have at LEAST _____ progressively motile sperm
500 million
What are the 2 sites for breeding?
- uterine body
- deep horn insemination (with frozen semen)
Post breeding
Evaluate for fluid accumulation (4-24 hours)
- lavage and/or ecbolics if needed –> done w/ endometritis
- check for ovulation
- rebreed if mare fails to ovulate timely
Ecbolics increase ______
Contractility of the uterus
Frozen semen
Expect poorer results
- more intensive management
- lower per cycle preg rates (30-60%) –> extreme stallion variability
Hormone levels
Progesterone levels during estrus should be basal (0-0.5 ng/ml)
- use mare side tests for quick results
Manipulation of estrous cycles
- AI
- shortening duration of late transition
- induction of ovulation
- synchronization of estrus
- foal heat breedings
Drugs used to manipulate mares
- prostaglandins
- progestins/progesterone
- hCG (acts like LH)
- GnRH analogs (deslorelin)
Prostaglandins
CL is susceptible by day 6 of cycle
- 5 mg Lutalyse or 250 ug Cloprostenol (never give IV –> sweating, colic)
- will not shorten interovulatory interval much
- always palpate or US the mare prior to giving prostaglandins
Progestins
Artificially lengthen luteal phase
- regumate or altrenogest
- progesterone in oil
- CIDR’s - inserted vaginally where progesterone is absorbed
Progestin use
Administer for 10-14 days
- discontinue use and give PG, mare should then enter estrus
- variable interval to ovulation (4-12 days)
- progestins inhibit estrus but not necessarily ovulation
Progesterone and Estradiol
150 mg progesterone and 10 mg estradiol
- give IM daily for 10 days
- give PG on last day of treatment
- breed on day 19-20
P&E inhibits _____
Both estrus and ovulation
- normal cycle resumes after administration
- infections may cause muscle soreness
- ovulation occurs on smaller follicles (35 mm)
- most predictable protocol for mares*
hCG
Give when growing follicle is 35 mm or larger and there is good edema
- expect ovulation to occur within 48 hrs
- repeated doses w/n a season may diminish effectiveness
Deslorelin
GnRH analogue
- administer when growing follicle is 32 mm or larger and edema is present
- expect ovulation within 48 hrs
- effectiveness does not diminish w/ repeated doses
- sucromate is only FDA approved product
Foal heat
First post-partum estrus
- ovulation on day 8-11 after foaling
- fertile estrus
- only way to back a mare up
Foal heat breeding
Examine mares closely for uterine fluid
- don’t breed if she is going to ovulate prior to day 10
- prostaglandins to short cycle after foal heat
Expectations
Per cycle pregnancy rate of 65-70% is ideal when both mare and stallion are fertile
