Exam #3: Repro Pt. 1 Flashcards
Structure and tubular tract of mare repro tract
- Two ovaries: bean shaped
- Tubular tract = paired oviducts, paired uterine horns, single uterine body, cervix (external os and fornix), vagina, vestibule, and vagina
What’s special about the equine ovary?
Inverted compared to other ovaries = inner cortex, outer medulla, ovulation fossa is internal (where ovulation occurs, includes surface germinal epithelium)
Where do we interrupt oocyte migration for oocyte transfer?
Infundibulum, before it enters the oviduct
Where does fertilization occur?
Ampulla of the oviduct
Where, in the female repro tract, is the sperm reservoir and deep insemination site?
Oviductal papilla, at the utero-tubal junction
Where is the more superficial and common insemination site?
Just past the cervix? - Go dorsal in the vagina (otherwise you’ll inseminate the bladder)
Extent of the vagina and vestibule, anatomically
Vagina = from external os of cervix to vestibulovaginal junction (up to the transverse fold, covering the urethral opening)
Vestibule = vestibulovaginal junction to vulva (includes urethral opening)
Clinical importance of clitoral sinuses and clitoral fossa
Sinuses = dorsal to clitoris Fossa = ventral to clitoris
*Places that can potentially harbor venereal pathogens
Three physical barriers protecting the uterus
1) Vulva
2) Vestibulovaginal junction
3) Cervix
Position of epididymal tail and testes in the stallion
Testes = inguinal position
Epid. tail = should be caudal (not caudal? May indicate torsion)
What tissue surrounds the urethra and forms the glans penis/corona glandis?
Corpus spongiosum penis
Accessory sex glands in the stallion
> Have all three = vesicular glands, prostate, and bulbourethral (difficult to palpate) glands
- Ductus deferens become the ampulla
What important structures are on the tip of the stallion penis?
- Urethral process = ventral
- Fossa glandis and urethral sinus = dorsal (where smegma can be impacting, harbor veneral disease)
Definition and clinical signs of puberty
> First achievement of the capability of successfully sexually reproduce
+ Maturation of genital organs
+ Development of secondary sex characteristics
+ Psychosocial interaction
Age of puberty of fillies and stallions
- Filly = 15 months (range 8-37)
- Stallions = 2.5-4.5 years (start producing sperm at 19 months)
Things that influence puberty (6)
- Breed = light weight horses come into puberty sooner than heavy draft breeds
- Season of birth (born late in year, have to wait another year to come into heat)
- Nutrition
- Management
- Systemic disease
- Parasites
When do we start breeding fillies?
2-3 years (ideal) time, depending on breed and purpose
Any earlier (< 2 yrs) = irregular cycles, higher abortion rates
Seasonality and cyclicity of mares? Four phases?
Long day seasonal breeders (majority have winter anestrus) - POLYESTROUS
1) Spring transition
2) Ovulatory seasons
3) Fall transition
4) Anestrus
What hormones play a role in the seasonality of the mare’s cycle?
Increasing light/photoperiod = seen by retina, decreased secretion of melatonin from pineal gland = signals hypothalamus to secrete GnRH and pituitary gland to secrete LH, FSH = follicular growth, and increasing estrogen
Main events of the spring transition
> After winters solstice
- Late winter = increasing FSH but inadequate LH to ovulate
- Increasing steroidogenesis (estradiol) and follicle development, secrete LH
- End of transition = sufficient LH to ovulate (first ovulation of the year)
Official birthday date program, and operational/physiologic breeding seasons
- Birthday date (official) = all born on Jan 1st
- Operational breeding = Feb 15th-July 15th
- Physiologic = May to October
Use of artificial lighting in the spring transition
> > 14-16 hours
- Minimum - 14.5 hours, 16 hrs is more common
- Increase light in 30 min increments
- Exposure in the evening»_space; more important than morning
- Start on Dec 1st, to ensure she’s cycling by Feb 15th (8-10 wks to first ovulation)
- GOAL = make the spring transition earlier
OTHER = 1-hr pulse of light, 18.5 hrs after onset of daylight or 9.5 hrs after onset of darkness
Role of P4 in manipulating the spring transition
> Suppress LH = increase LH reserve available
- 10-15 days of P4, then PGF –> estrus in 3-7 days
+/- Addition of estradiol = stronger gonadotropin suppression (suppresses FSH)
Role of GnRH in manipulating the spring transition
Increase FSH/LH ==> IMPRACTICAL to administer frequently enough
Role of dopamine (D2) receptor antagonists
Increase in prolactin = increase of estradiol production from follicles = advances first ovulation (works better with artificial lighting)
Estrous cycle length of mares
21 days (19-24 days)
Estrus duration
7 days
Diestrus duration
14 days
Hormonal indication of estrus
< 1 ng/mL of progesterone
Clinical signs of estrus in the mare
> Receptive to the stallion \+ Stands calmly \+ Squats \+ Winks vulva \+ Urinates \+ Flags tail
Soft uterus and cervix, edematous endometrial folds, open/moist/pink cervix, follicles on ovary, no CL
When does ovulation occur in regards to estrus?
In the last 48 hrs of estrus
Clinical signs of diestrus
> Non-receptivity to the stallion \+ Agitated in the presence of a stallion (false positive if with a foal) \+ Kicks \+ Squeals \+ Swishes tail \+ Ears back
Firm endometrium (no folds or edema), uniform endometrium echogenicity on U/S, long/narrow cervix, closed/dry/pale cervix, CL on ovary, varying sized follicles
Hormonal indication of diestrus
> 1 ng/mL of progesterone = active and present CL
How does natural luteolysis occur in the mare?
PGF-2-alpha = released from endometrium to GENERAL circulation (affects both ovaries)
Pituitary, uterine, and ovarian hormones during estrus
- Pituitary = FSH, LH (induce ovulation, lutenize into CL)
- Uterus = PGF2
- Ovary = estradiol (follicle), inhibin (from follicle), P4 (CL)
Major and minor follicular waves
> Depends on the size of the follicle
MAJOR = Largest follicle of the wave attains the diameter of the dominant follicle (> 28 mm)
MINOR = Largest follicle of the wave doesn’t become dominant, max diameter ~ 23 mm
Primary and secondary follicular waves
> Depends on whether ovulation occurs or not
Primary = wave emerge mid-cycle (day 10), dominant follicle evident ~7d before ovulation, ovulation DURING ESTRUS
Secondary = wave emerges in early diestrus, ovulation may occur during diestrus (other option = regress during estrus)
What is deviation in the follicular wave?
Point at which the largest follicle becomes the dominant follicle (grows at the same rate), and all other follicles regress (growth rate slows down)
*Thought to be due to the transition between FSH and LH
Dominant follicle produces estradiol and inhibin
Estrogen during the mares cycle
- Increases during estrus, peaking one day before ovulation
- Low during diestrus
LH during the mare’s cycle
- Increases during estrus, before ovulation, peaks just after ovulation
- Low during diestrus
P4 during the mare’s cycle
- Low during estrus
- High during diestrus
FSH during the mare’s cycle
- Larger peak at the end of diestrus = preparing for the primary wave
- Smaller peak at the end of estrus = may induce a secondary wave
PGF during the mare’s cycle
- Peaks at the end of diestrus
- LOW during estrus
Activity during the fall transition
- Longer in length than spring transition
- ABNORMAL CYCLES: prolonged/short diestrus, anovulatory follicles (increase in echogenicity), hemorrhagic follicles, silent heats
Activity of anestrus
> ANOUVLATORY season
- Follicles are < 15 mm
- No CL is present
- Poor uterine tone
Differences of seasonality in the stallion and the mare
Effects of season and day length are not as dramatic in stallions and mares
Affects = testicular size, semen production, libido, hormone concentrations (decrease light, increase in melatonin, decrease in GnRH)
Two main mating systems and management
1) Natural service/cover:
a- Pasture mating
b- Pen mating
c- In-hand mating
2) AI:
a- Fresh semen
b- Cooled semen
c- Frozen semen
How to pasture mate, Pros/cons
> Stallion on pasture with a group of mares (all in different parts of their cycle
- Requires experience stallions that know what they’re doing
- Examine mares are frequent intervals to see who’s pregnant
- Pros = save labor, achieve good conception rates
- Cons = high risk of breeding injuries (esp to young/inexperienced stallions), poor breeding records if not kept track of, transfer of venereal disease
How to pen mate, Pros/cons
> Mare in estrus in a pen with a stallion
*Not really used much
- Pros = more control, may allow you to train young stallions
- Cons = more labor, risk of breeding injuries
How to in-hand mate, Pros/cons
MOST COMMON form of natural mating = mare is restrained and the stallion is brought over
- Pros = good supervision and interaction (less injuries), controlled hygiene (less veneral disease), able to keep good records
- Cons = labor intensive, limited interaction between mare/stallion
What do you have to remember with stallions who only know how to in-hand mate?
Modifies their pre-copulatory behavior = won’t try and tease the mare, will just mount
Pros/cons of artificial insemination
- Pros = achieve genetic progress (more mares bred to stallions), ensure semen quality, safer, decreased disease transmission
- Cons = lower conception rates (cooled, frozen), high labor
What should you always do with any semen (fresh, cooled, frozen)?
Ensure quality (motility, morphology, etc).
Indications for performing a mare BSE (4)
1) Routine management
2) Diagnostic for subfertility
3) Pre-purchase exams
4) Embryo transfer recipient
Parts of the a mare BSE (5)
1) Signalment and history - age, breed, use of horse, past repro performance, prior dx tests or procedures
2) PE: TPR, BCS, coat, lameness, chronic condition, vax, parasite control, inspect udder/perineum
3) Rectal palpation
4) U/S
5) Libido = examine the mare before exposure to the stallion
+/- Endometrial cytology and culture
+/- Vaginoscopy, hysteroscopy, endometrial biopsy, endocrine teting
Ideal vulvar conformation
- Vertical (< 10% angle)
- More than 80% of vulva below the level of the ischial tuberosities (floor of the pelvis)
Causes for small/inactive ovaries in the summer (6)
1) Prepubertal
2) Anestrus - stress, poor health, post-partum, exogenous anabolics, chromosomal abnormalities
Two reasons for persistent CL on ovaries
1) Diestric ovulation = prolonged diestrus, ovulated to close to PGF release to undergo luteolysis
2) Failure of luteolysis = endometrial conditiosn
Reasons for hemorrhagic anovulatory follicles (4)
1) Fall transition
2) Stress
3) Metabolic problems
4) Ovulatory problems (luteinization or not)
Dx? Mare with abnormal behavior (anestrus or estrus w/o cause), stallion-like behavior
Granulosa cell tumor = slow growing and benign (won’t met)
DDx: anabolic steroid admin
Palpation and U/S findings of granulosa cell tumors
- Enlarged ovary unilateral (less frequent = bilateral)
- Multicystic or honeycombed on U/S (one large cyst = less frequent)
Hormonal changes you can test for with granulosa cell tumors
- Increase in steroid hormones = testosterone
- INCREASED INHIBIN = suppresses FSH, stops the mare from cycling = low P4 and estradiol
- Anti-mullerian hormone = specific to granulosa cell tumors, more sensitive?
Treatment of granulosa cell tumors
Surgical extraction of affected ovary, contralateral ovary should resolve in 6-8 months (depends on how long the tumor has been there before things resolve)
Problem with uterine cysts
- No problematic unless they become too numerous to too large in size
- RECORD IT = helps you differentiate between a uterine cyst and a pregnancy when you breed the mare
Diagnosis of endometritis
+ U/S = fluid in uterus
- Cytology = covered swab/cytobrush or low volume lavage (w/ centrifugation), put on slide and dye
- Culture
- Biopsy
*Examine at least 5 fields w/ 40x power to obtain an average # of neutrophils (1-2 = mild inflam, 3-4 = mod, >5 = severe)
What may you want to perform if you have a history of infertility, persistent uterine fluid, positive cytology (infection), genital discharge, or if the owner just plain requests it?
Endometrial culture - DO IT BEFORE CYTOLOGY
- Prep/rinse
- Guarded swab with glove and non-spermicidal lube, have transport media ready
- Collect
- Streak on plate and incubate for 3 days
- Follow-up = clitoral fossa/vaginal cultures, anaerobic cultures
Interpretation of positive culture and cytology
Uterine infection
*If it fits with clinical signs
Interpretation of positive cytology and negative culture
Uterine irritation/inflam
*If it fits with clinical signs
Interpretation of negative cytology and positive culture
Contamination of culture sample
*If it fits with clinical signs
True or false - sampling 1-3 locations in the distal body or proximal horn with endometrial biopsy will give you a sample that is representative of the whole uterus
True
Endometrial biopsy categories and general interpretation
As the categories increase = probability of conceiving and foaling decreases
Two main causes (etiologies) of endometritis
1) Post-breeding = “normal” uterine clearance of semen
2) Infectious = bacterial more commonly than fungal
- Etiologic = Strep zooepidemicus, E. coli, Pseudomonas, Klebsiella, Taylorella
What do these things pre-dispose a mare to: poor vulvar conformation, cervical incompetence, pendulous uterus (difficult to clear fluid), frequent natural breeding (no time to clear uterus), persistent hymen (doesn’t allow fluid to escape), endometriosis?
Endometritis
Treatment of endometritis
- Address any primary problems
- Uterine lavage - until the lavage fluid comes out clear
- Ecbolics (oxytocin, PGF) = increase uterine contractions, PGF lasts longer but is weaker (don’t use after breeding)
- Correct any predisposing factors
Is pyometra common in mares?
NO
