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306 Cards in this Set

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When during the estrus cycle does ovulation occur in the mare?
24-48 hours before end of estrus.
When is the ideal time to breed a mare in relation to her estrus cycle?
Right after the peak in estrogen, as evidenced by maximal uterine edema per ultrasound
What about the mare's LH release is unique in comparison to other species?
Broad based LH curve, rather than a spike like other species
What is unique about the anatomy of the equine ovary?
All ovulations through the ovulation fossa.
These structures stimulate formation of secondary CL's to help maintain pregnancy from day 40-120.
Endometrial cups
The equine pregnancy is CL dependent until what point in gestation? Why?
Around day 100 as the fetus begins secreting its own progestagens
What hormone is secreted by the endometrial cups? What does this hormone do?
eCG, stimulates production of secondary CL's to secrete additional progesterone.
This hormone rises in the pregnant mare from day 80, then gradually declines after day 200.
This hormone peaks just before parturition and falls right at time of delivery.
How long is the AVERAGE equine gestation?
343 days, or 11 months
Foal heat occurs this long after parturition.
7-14 days (average 9-10)
If a mare is bred on her foal heat, she will be more fertile this many days after parturition. Why?
Day 9... Gives uterus time to clean out.
The mare's breeding calendar may be advanced by one month each year if she is bred before...
Day 25 post-partum
List some signs of estrus in the mare.
Ears not back
Winking vulvar lips
Tail raised
If a mare doesn't breed on her foal heat, how can she be brought back into estrus in time to advance her next parturition by a month?
Short cycle with prostaglandins
List some ways in which exogenous progestins may be administered.
Progesterone in oil IM qd
Altrenogest po qd
Bio-Release P4 LA 150 every 10 days
Progesterone implants
DepoProvera (medroxyprogesterone acetate) IM every one to three monts
Why can't progesterone implants be counted on to maintain pregnancy?
Less reliable distribution b/c SQ
How would one manipulate lighting to start the transition cycle of the mare? Include time intervals.
Lights 16 hrs daily (100 watt bulb per 12X12 stall) for 60 days, adding 2-2.5 hours per night until maximum reached.

Or 1 hour pulse 9.5 to 10.5 hours after onset of darkness to reset the brain.
If you want a mare to go into a fertile estrus around February 15th, when would you begin putting her under artificial light?
Decemebr 15th.
This hormone suppresses production of GnRH in the mare.
What stimulates production of melatonin in the mare?
Increased darkness
For how long would altrenogest be given to shorten the transition period in the mare? Then what else is given?
9-14 days, then give prostaglandin to lyse CL
This dopamine antagonist has been used with mixed success to shorten the transition period in the mare to 14-21 days.
The size of an ovulatory follicle in a mare is roughly...
30-35 mm
List three compounds that are effective at maintaining an equine pregnancy.
Progesterone in oil IM qd
Regumate po qd
BioRelease P4 LA (IM at 10-14 day intervals)
How does progesterone aid in pregnancy maintenance?
Helps prevent CL lysis in event of prostaglandin release before 100 days
Increase in uterine gland secretion
Increases embryonic growth factors
Quiets myometrium, closes cervix
List some drugs that may be given to help halt an impending abortion in the mare
Altrenogest po qd X 2
Progesterone in oil IM qd
Banamine bid po/iv
Pentoxyphiline bid
Tocolytics to (-) smooth muscle contraction
How can ovulation be postponed pharmacologically?
Oral progesterone given for 3 days, delays LH peak by 1.5 days
What is the downside of using progesterones to delay ovulation?
Could increase incidence of anovulatory follicles
This hormone inhibits LH secretion.
Describe how progesterone and estradiol may be used together to reset the mare's estrus cycle for synchronization. When will ovulation occur with this system?
Progesterone and estrogen for 10 days, then give PGF on day to lyse CL. Ovulation on day 21.
Major form of estrogen in criculation, generated by fetus and placenta.
Estrone sulfate
Used as a hormonal marker of pregnancy after day 80 or so.
Estrone sulfate
What is the possible function of estrogens during gestation?
Luteotropic, responsible for maintaining secondary CL's.
What hormonal changes would indicate either impending parturition or abortion in the mare?
Progesterone spike
Drop in estrogen
When deslorelin is used to induce ovulation, how long before it occurs?
Ovulation in 38 +/- 2 hours
How is hCG used to stimulate ovulation in the mare if she is being bred by AI?
Give hCG, ovulation occurs 24-48 hours later.
Breed at 24 hrs and 40 hrs.
What are some concerns with use of hCG to ovulate an aged mare?
Less effective, maybe due to receptor issues or antibody effects.
What would be best to ovulate an older mare at the end of the season, and why: deslorelin or hCG?
Deslorelin: Tighter ovulation window, and hCG associated with less efficacy in older mares.
In the spring transition period, which gonadotropin is produced first by the pituitary?
When attempting to ovulate a mare in the transitional period, would deslorelin or hCG be more effective, and why?
hCG, because it operates at the ovarian level by increasing LH activity. Deslorelin acts on the pituitary to stimulate LH production; however, FSH is the predominant hormone being produced early on.
What undesirable pregnancy side effect is associated with hCG use?
Double ovulations and twinning
List the two physiologic responses to oxytocin.
Milk letdown
Uterine contraction
How can oxytocin be given to suppress estrus in the mare?
Dose bid on days 7-14 AFTER ovulation, and will maintain CL beyond 40 days
How can ocytocin be given to help prevent a post-partum metritis.
6 hrs apart on day 1
4 hours apart on day 3
The effects of prostaglandins
Contraction of smooth muscle
Lysis of CL
Which ecbolic will produce a more prolonged contraction of smooth muscle: oxytocin or prostaglandin?
Natural prostaglandin drug name and brand name
Dinoprost tromethomine, aka Lutalyse
Synthetic prostaglandin drug name and brand name.
Cloprostenol, aka. Estrumate
How can the dose level and administration timing of prostaglandins be modified to reduce side effects?
1/10 normal dose for 2 days in a row
If short cycling a mare with prostaglandins, how long after ovulation must you wait?
5-6 days
When is prostaglandin used to manipulate uterine tone for reduction of post-breeding metritis?
Use prior to ovulation
Why should PGF not be given to a mare after ovulation to prevent metritis?
Decreases progesterine concentration and reduces pregnancy rate.
When is prostaglandin used to manipulate uterine tone for reduction of post-breeding metritis?
Day of ovulation, to post-ovulation
What are some side effects of PGF administration in the mare?
Sweating, colic, inappetance, lasting 15-20 mins
How is isoxsuprine used to preserve a pregnancy? Low long does it last?
Tocolytic, stops uterine contractions, lasts 1-2 hours
Why should isoxsuprine not be used in a mare in near-term pregnancy?
SE to foal: Tachycardia, hypoglycemia, hypocalcemia, ileus, hypotension
Clenbuterol is used for this purpose in a pregnant mare.
Tocolytic, stops uterine contractions to halt impending abortion.
This tranquilizer decreases myometrial activity.
These two tranquilizers increase myometrial activity.
Why would dexamethosone or prednisolone be given around the time of breeding?
Decrease uterine fluid accumulation to improve fertility and reduce incidence of post-mating metritis.
What are some major effects of fescue toxicosis in the pregnant mare?
Prolonged gestation
Increaded placental weight
Retained placenta
Premature separation
Poor neonatal viability
How does fescue toxicosis affect progestogen concentrations in the mare?
Lower in affected mares
When should broodmares not be exposed to fescue?
During spring transition (delayed cyclicity)
First 30-60 days gestation
Last 30-60 days gestation
Once a mare is removed from fescue, how long will it take for her progestogen levels to increase?
3-5 days
Drug used to increase prolactin in the event of fescue toxicosis.
What is the therapeutic use of reserpine in the pregnant mare?
Calms mare and boosts milk production
Possible side effects of reserpine.
Neurologic effects
How does bromocriptine work? Why is it used?
Dopamine antagonist, used for treatment of Cushing's disease.
What is an undesirable effect of using bromocriptine in a cushingoid broodmare?
Decreased cyclicity, decreased milk production.
In a pregnant mare being treated for Cushing's disease with bromocriptine, when should the drug be stopped?
One month prepartum, +/- add domperidone
What is the "doubling rate" when evaluating stallion records?
Related to proportion of mares bred to that stallion more than once per cycle.
Is the pregnancy rate for a given stallion higher or lower early in the breeding season?
Higher--> Most females get bred in 1st 2 cycles, and the "problem" mares are the ones trying to get bred late in season.
Number of mares pregnant divided by total number of mares bred for the season.
Seasonal pregnancy rate
Number of cycles per season divided by number of pregnancies. Measure of the efficiency of the stallion at establishing pregnancy.
Pregnancy rate per cycle
What is the significance of the "doubling rate" for a stallion? Why does it matter?
Excessive covers or inseminations per cycle can result in overuse of a stallion and semen wastage.
Is the typical book size of a typical high-performing stallion increasing or decreasing over the years?
The average stallion has a book size of...mares per season.
How do you establish a stallion's DSO?
Collect him daily for 5-7 days to deplete extragonadal sperm reserves so that only one day's worth of semen is ejaculated.
What are some management factors that can affect stallion fertility?
Frequency of collection/breeding
Medications (steroids, progesterone, etc)
Housing (near mares, stallions, alone, etc)
Heat decreases sperm output
Why is exercise important for a breeding stallion?
Lack of exercise can result in behavior abnormalities
Strong legs, back, and good physical condition
Keep stalion alert, athletic, and content
This is the term for a stallion, often a shielded scrub pony, used to gauge mare receptivity.
Teaser stallion
Why are teaser stallions used?
Gauge receptivity of mares to minimize risk of injury to a more valuable breeding stallion
These barriers may be used when teasing a mare to determine estrus.
Mare in stall
Mare in stocks
Across teasing "wall"
Across phantom
What are some reasons that a mare may not be bred naturally?
Repro tract abnormality
Lameness, neurologic issue
Owner preference
Mare not receptive, even in estrus
Describe the testing protocol for EVA in a stallion.
Test stallion via serology
If negative--> vaccinate
If positive--> Culture semen
If semen positive--> Vaccinate mare
True or false: There is no risk of sexual transmission of EIA.
List the basic components of a mare BSE.
Physical exam and history
Conformation evaluation
Rectal palpation
Ultrasound evaluation
Vaginal speculum exam
Culture, cytology, biopsy
When in a mare's cycle should uterine culture be done?
Diestrus or early estrus
True or false: A fair number of mares can culture positive on uterine swab from contamination through the open cervix during estrus.
List three barriers to infection in the mare's repro tract.
Vestibulo-vaginal fold
During this stage of the mare's cycle, there is increased immunity in the uterus and decreased mechanical protection.
During this stage of the mare's cycle, there is decreased immunity in the uterus and increased mechanical protection.
Does a failure of immunologic or mechanical clearance tend to cause problems more commonly in the mare?
What concerns could there be with breeding a maiden 15 year old mare?
Nulliparous mares tend to have a decreased capacity for cervical dilation--> This leads to fluid accumulation in the uterus and predisposes the mare to post-mating metritis.
How long does it normally take a mare to eliminate uterine fluid following a challenge/mating?
Several hours
A normal mare should be able to clear bacteria from the uterus in...
36-48 hours
A mare is more susceptible to post breeding endometritis when she has one of the following factors:
Poor uterine defense mechanisms
Delayed uterine clearance
Poor uterine position
Unable to eliminate bacteria by 96 hours
Multiparous or older mared
How often should a "susceptible" mare be ultrasounded following breeding to ensure uterine clearance?
Intervals of 12-24 hours (Should be clear in 24 h)
True or false: Fluid in the uterus after breeding is a key sign of post-mating endometritis.
How long after breedig should the practitioner wait to do a uterine lavage, and why?
4 hours-- gives time for the oviductal epithelium to become saturated with sperm
How much fluid may be found in the mare's uterus after breeding before the DVM should be concerned?
Up to 2 cm
What are some downsides to doing a uterine lavage for cytology?
Time consuming
May cause inflammation
Requires sedimentation/centrifugation
This uterine swab has a single head for culture and a cap for collecting cytology samples.
Kalayjian swab
This uterine swab prevents accidental swab contamination by using outer and inner sleeves
McCullogh swab
Stain used to visualize vaginal cytology smears.
DiffQuik, aka Modified Wright's Stain
Normal biopsy grade, 80-90% exprected foaling rate
Grade I
Biopsy grade: Mild change, 50-80% expected foaling rate
Grade IIa
Biopsy grade: Moderate change, 10-50% expected foaling rate
Grade IIb
Biopsy grade: Severe change, Under 10% expected foaling rate
Grade III
Why is the distribution of uterine glands a good predictor of expected foaling rate?
Placenta interdigitates with endometrial glands, and so a loss of glands points to a loss of contact area and a potential for loss of pregnancy.
On what day of gestation does the embryo enter the utero-tubal papilla?
List some ways to determine oviductal patency.
Presence of embryo
Starch granule test
Fluorescent labeled beads (flow cytometry)
Flush oviduct surgically through the flank
List three reasons a mare may become infertile.
Failure to concieve
Embryonic loss
If a pregnancy is lost between days 40 and 120, why is the mare likely "lost" for the season?
Endometrial cups persist and stimulate progesterone production up through day 100-120 regardless of whether the mare is still pregnant.
List some reasons for a non-cyclic mare.
Not bred b/c not found in heat
Retained endomertial cups
Prolonged diestrus/pseudopregnancy
Gonadal dysgenesis
Out of season
Behavioral anestrus
Ovarian shutdown
Occurs when the CL lifespan is prolonged beyond 15 days.
Prolonged diestrus/pseudopregnancy
List some reasons for a prolonged diestrus or pseudopregnancy.
Diestral ovulation (immature CL not responsive to PGF when released)
EED after maternal recognition
Failure of PGF release due to uterine abnormality
Luteal cyst
How would prolonged diestrus due to a luteal issue be resolved?
Donoprost, exogenous PGF
A non-cycling mare is very small in size for her age, and has very small, form, smooth ovaries. Her uterus and cervix are thin and flaccid. What could be the problem?
Gonadal dysgenesis due to chromosomal abnormality
This pseudohermaphrodite is genetically female and has a penis where the clitoris would be. More common of the two types.
Male pseudohermaphrodite
This pseudohermaphrodite is genetically male, has ambiguous-to-male external genitalia, and ovaries.
Female pseudohermaphrodite
Most common type of ovarian tumor in the horse.
Granulosa-theca cell tumor
What hormonal tests would help to screen for a granulosa cell tumor?
Inhibin and testosterone
Why, in the event of a granulosa cell tumor, would the opposite ovary be very small?
Tumor secreting inhibin
What is the treatment for a granulosa cell tumor, and how long before the mare cycles normally?
Remove affected ovary and other one should resume cycling soon, based on the time in the season when Sx done. Average of 8 months.
What factors could drive a mare into behavioral anestrus?
Novel environment
Too familiar with stallion
Dislikes stallion
Maiden mare
Mare with foal
How can a mare in behavioral anestrus be brought around?
Careful teasing, frequent palpation, PGF to synchronize estrus, AI or restraint for breeding
This condition is similar to cystic ovarian disease in cattle, leading to increased progesterone production.
Anovulatory follicle
Mares tend to undergo reproductive senescence around age...
25 years
List some reasons for ovarian shutdown in the mare.
Anolvulatory follicle
Reproductive senescence
Negative energy balance
Anterior pituitary dysfunction
How can a luteal cyst be treated in the mare?
Dose with PGF
How can a follicular cyst be treated in the mare?
No Tx: Wait for it to luteinize (80% will) then give PGF.
Inflammation of the inner layer of the uterus
Why is post-mating endometritis such a cause for worry?
Associated inflammation after embryo in uterus may cause PGF release and luteolysis, or directly affect embryo.
Mucus in uterus is secreted by the...
How will uterine mucus production change with acute infection?
How will uterine mucus production change with chronic infection?
List some commonly used biofilm-mucus disruptors.
What kind of semes in most commonly associated with post-breeding endometritis?
Frozen semen
Why is frozen semen more frequently associated with an exaggerated inflammatory response than is fresh semen?
Seminal fluid seems to decrease inflammatory response
Why is seminal plasma often removed from frozen semes samples-- besides to save space?
Seminal fluid shortens sperm lifespan, activates sperm.
List two equine veneral diseases that may cause endometritis.
How is endometritis treated?
Augment uterine clearance with ecbolics
Local or systemic Abx as needed
Return to estrus QUICKLY to open cervix and (+) immune system
List three ways in which the mare's genital barriers may be made more effective.
Vulvoplasty (Caslick's)
Urethral extension
Cervical repair
True or false: Warm uterine lavage stimulates uterine contraction.
Would lactated RIgner's solution or normal saline be a better choice for uterine lavage, and why?
More physiologic pH, less irritating
This ecbolic may be administered as soon as 4 hours after mating to speed uterine clearance.
This ecbolic may not be given on or after the day of ovulation to speed uterine clearance.
Chronic degenerative endometritis due to wear and tear on uterus over time.
Endometrosis is more commonly seen in mares of this age
13-14 years or older
This degenerative reproductive disease is marked by fibrosis, lymphatic stasis, uterine sacculation, adhesions, diverticuli, and endometrial/lymphatic cysts.
How may endometrosis be treated?
No specific, reliable reversal.
Mechanical currettage, biopsy
Hypertonic saline
Magnesium sulfate
Hydrogen peroxide
What is the goal of endometrosis treatment?
Inducing superficial endometrial inflammation, necrosis, and loss of damaged tissues
List some of the benefits attributed to DMSO.
Activate complement
Aid PMN opsinization
Decrease inflammatory damage
Reduce endometrial fibrosis
When does metritis usually occur in the mare?
Massive contamination of the uterus with or without trauma
List a major cause of sustemic illness from metritis
Gram negative organisms--> Endotoxemia
How does metritis differ from endomertitis?
Metritis: Deeper uterine layers affected
Endometritis: Only endometrium inflammed.
True or false: Metritis is a medical emergency in the mare.
True or false: A mare with pyometra most often shows no clinical signs.
When signs of pyometra are noticed, they typically include:
Pain on performance from weight of uterus
Vulvar discharge
Pyometra is associated with which ovarian structure?
What is the prognosis for future fertility once a mare has has pyometra?
Poor due to endometrial damage and cervical pathology
How is pyometra treated in the mare?
PGF to lyse CL
Drain large volumes slowly
Uterine lavage with ecbolic
Systemic antibiotics
List some anatomical incompetencies that may cause infertility in the mare.
Cervical incompetence
Cervical adhesions
Rectovaginal fistula
Perineal body incompetence
List some factors that may affect oocyte quality.
Age of mare
Age of oocyte since ovulation (deteriorates after 8-12 hrs)
Nutritional status of mare
What does it mean for a mare to be subfertile?
She can conceive but cannot maintain a pregnancy due to EED.
Lack of uterine glands can decrease production of
Early embryonic death takes place before
Day 45
Abotrion occurs when the fetus is expelled between
Organogenesis (day 45) and survivability (day 300)
Foal born prior to 320 days gestation
Premature foal
Foal who has signs of prematurity, but was born after 320 days gestation
Immature foal
Immature foal associated with placentitis or ammonitis.
Dysmature foal
Foal born after 365 days gestation
Postmature foal
List some factors affecting embryonic loss in the mare.
Major stress
Seasonal and climatic factors
Maternal age
Lactation and foal-heat breeding
How would you go about trying to pinpoint the cause of an abortion?
Examine fetus internally/externally
Serum from mare
Examine placenta, especially near cervical star
Weigh placenta
TIssue samples from blood-filtering organs
List three routes of placental infection.
Previous intrauterine infection
How can you tell if abortion occurred as a result of transcervical infection?
Look at the cervical star to see if there is purulent material, scarring, etc.
Common bacterial cause of abortion.
Streptococcus zooepidemicus
If an abortion is due to bacterial infection, how will the placenta appear?
If an abortion is due to viral infection, how will the fetus appear?
List some non-infectious causes of abortion.
Twisted umbilical cord
Uterine body pregnancy
Endocrine dysfunction
Extensive uterine fibrosis
Endometrial cysts
Endometrial atrophy
List some ways in which abortion may be induced in the mare.
Prostaglandins (multiple injections, especially before day 90 but all through)
Manual cervical dilation with fingers
Nutrition (poor nutrition or fescue)
What kind of twins are more common in the equine: monozygotic or dizygotic?
Do most equine dizygotic twinning events result from synchronous or asynchronous ovulations?
Asynchronous (over 24 hours apart)
Why are asynchronous ovulations possible in the equine?
Broad-based LH curve
What feature of the equine embryo prevents pinching and monozygotic twinning?
Twinning is more frequent in these breeds of horse.
Thoroughbred and draft mares
Are twins more frequent in older mares (6-10) or younger mares (2-5)?
What is the most frequent outcome of a twin pregnancy?
Birth of a single foal
How frequently are both twins lost in the equine twin pregnancy?
31% of the time
How frequently are both twin foals born alive?
1% of the time
At what point in the pregnancy can a twin pregnancy be diagnosed per ultrasound?
Day 14-16
What event occurs at day 16 of the equine pregancy?
Fixation (embryo sticks to uterine wall)
Why should twin elimination occur ideally before fixation at day 16 of pregnancy?
It is difficult to crush only one embryo if both are fixed in close proximity.
How can natural reduction of a twin pregnancy occur after fixation?
Orientation of twin vesicles within uterine lumen--> Less placental contact and nutrient deprivation of one twin
Is natural reduction of a twin pregnancy more likely with a unilateral or bilateral fixation of embryos?
Describe the kind of twin placentation in which one fetus in in the horn and one fetus is in the body of the uterus. Twins are dissimilar in size.
Type A.
Describe the kind of twin placentation in which both fetuses are of equal size and both in the uterine body.
Type B
Describe the type of twin placentation in which one twin is undergoing mummification and one is alive.
Type C
Most common form of twin reduction.
Ultrasouns assisted crushing
When is ultrasound-assisted crushing of a twin vesicle best done?
Prior to day 16
Type of fetal reduction more commonly done after fixation.
What is the major risk associated with fetal aspiration?
Reduction of both embryos
What is the success rate of fetal cranio-cervical dislocation?
71% success, but 30% need to be repeated 10 days later
How long does it take for the fetal heartbeat to stop following cranio-cervical dislocation?
1-3 weeks
At what point in gestation is cranio-cervical dislocation done?
60-110 days gestation
Intra-cardiac perfusion with this drug is commonly done to reduce a twin.
Procaine penicillin
Before day 35 of gestation, how may a mare be aborted with drugs? How long before the mare may be expected to return to estrus?

Return to estrus in 5-7 days
After day 35 of gestation, how may a mare be aborted with drugs?
Prostaglandins, multiple shots over 3-5 days
Late natural reduction may occur up to this point in the equine pregnancy.
Day 60
A fetus that dies in the absence of bacterial infection and undergoes reabsorption of fluids and contraction of the uterus is said to have undergone...
Death of a fetus with bacterial contamination results in...
This condition is the result of an abnormal allantoic membrane, and causes the rapid accumulation of fluid over 10-14 days. Occurs late in gestation, after the 7th month.
Hydrops allantois
Clinical signs associated with hydrops allantois.
Reluctance to move, altered gait, and dyspnea
Rapid distension over 10-14 days
What is the treatment for hydrops allantois?
Induce abortion, manually dilating cervix and puncturing membranes
Give oxytocin and run IV fluids
Possible complications of hydrops allantois.
Hyopvolemic shock after delivery
Ruptured prepubic tendon, herniation, abdominal muscle rupture, uterine rupture
Slow accumulation of amniotic fluid over weeks to months.
Hydrops amnii.
Which condition occurs more frequently in the mare: hydrops allantois, or hydrops amnii?
Hydrops allantois
How is prepubic tendon rupture addressed in the mare? What is the prognosis?
Goal= save foal? Then support with sling or heavy canvas

Goal = save mare? Induce parturition

Most ruptured mares are destroyed. If a partial tear, mare may survive but should not rebreed
What anatomical feature makes uterine torsion rare in the horse?
Dorsal uterine attachment of broad ligament
When in gestation does uterine torsion occur?
Months 5-10
Clinical signs of uterine torsion in the mare.
None, to colic, restlessness, frequent urination
How is a diagnosis of uterine torsion made?
Rectal palpation
When correcting a uterine torsion, should the mare be twisted in the direction of the torsion or the opposite way?
Direction of the torsion
Cause of slight recurrent vaginal bleeding in older multiparous mares late in gestation.
Vaginal varicose veins.
How are vaginal varicose veins treated in the mare?
Ligation, cautery, or laser ablation if severe
Usually a result of mutation and fetotomy or violent intrapartum movements in the mare.
Uterine rupture
How is a diagnosis of uterine torsion made?
Rectal palpation
When correcting a uterine torsion, should the mare be twisted in the direction of the torsion or the opposite way?
Direction of the torsion
Cause of slight recurrent vaginal bleeding in older multiparous mares late in gestation.
Vaginal varicose veins.
How are vaginal varicose veins treated in the mare?
Ligation, cautery, or laser ablation if severe
Usually a result of mutation and fetotomy or violent intrapartum movements in the mare.
Uterine rupture
Major cause of prolonged gestation in the mare.
How does photoperiod affect equine gestation length?
10 days longer in early spring than in mid summer
At what point is an equine gestation considered prolonged?
After 360-380 days
True or false: The equine fetus may undergo developmental arrest in early pregnancy for several weeks.
What should be done about prolonged gestation in the mare?
Try to wait for normal parturition.
Rule out possible inciting causes
Low levels of this hormone result in agalactia.
Possible effects of fescue toxicosis in the mare include:
Decreased milk
Prolonged gestation or abortion
Weak or dead foals
Thickened placenta
Drug used to treat fescue agalactia.
Mares should be removed from fescue at what point in gestation?
30-45 days before due date
How long before parturition does a thickened placenta occur as a result of fescue toxicosis?
48 hours prepartum
Reasons a mare may be considered to have a high-risk pregnancy.
Previous gestational problems
Previous health problems with abdomen or pelvis
Owner preference
What kind of control does the equine fetus have over oxygen delivery to the uterus?
Initial fetal response to hypoxia.
Decreased CO, vasoconstriction, increased umbilical vein resisitance.
If fetal hypoxia persists, how will the fetus respond physiologically?
Tachycardia and loss of fetal activity

Then terminal bradycardia
This hormone causes the relaxation of the tail head ligaments.
What is the significance of a decrease in estrogen mid gestation?
Impending abortion/premature delivery
When would a transabdominal ultrasound be indicated in the high-risk pregnant mare?
Premature lactation or udder development
Vaginal discharge
History of stillbirth
Prolonged gestation
Recently corrected uterine torsion
Excessive absominal size
Apparent abdominal pain
Severe systemic illness
Owner request
How should amniotic fluid appear on ultrasound?
Anechoic, small amount of debris if fetus is motile
Five things to evaluate on a transabdominal ultrasound if there is a high-risk preganancy.
Character of fluid
Fetal movement
Fetal tone
Fetal breathing movement
Maximal amniotic/allantoic fluid pocket depths
How should the depth of the amniotic fluid compare to that of the allantoic fluid?
Amnion = 1/2 allantoic fluid
What should be done if a fetus is bradycardic on ultrasound?
Check back in 1-2 hours, correlate with fetal movement
Baseline fetal heart rate in late gestation
Which is more common in the fetus: bradycardia or tachycardia?
Bradycardia common, ominous if consistent
How does fetal heart rate change with gestational age?
Decreases as fetus matures
How thick may the uteroplacental unit fougly appear on ultrasound?
<2 cm
Is the placenta thicker per ultrasound in the fetal horn or non-fetal horn?
Non-fetal horn
List some ways in which fetal size may be evaluated per ultrasound
Biparietal diameter/ head width
Orbital diameter
If there is clotted blood in the umbilicus on ultrasound, what does this mean?
Dead fetus
What is CTUP?
Combined thickness of uterus and placenta (assumed to be measured transrectally)
Normal CTUP for days 301-330 gestation
Under 10 mm
Where should CTUP be measured?
At cervical star
Anatomical landmark for finding cervix on ultrasound
Middle uterine artery
Estrone sulfate level is high after this point in gestation.
60-90 days
What does a high estrone sulfate reading in an at-risk pregnant mare tell you?
Foal was alive at least a couple days ago
Hormone is consistently increased in mares with advanced placentitis
List some of the best predictors for readiness of birth.
Udder formation, presence of colostrum
Increase in milk calcium content
Relaxation of cervix
Gestational age of over 330 days
How soon before parturition does waxing tend to occur?
1-2 days prepartum
Consequences of an un-relaxed cervix
Longer time from induction to delivery
Possible increase in intra-parum asphyxia
Longer time to stand and nurse
Increased risk of placental separation and dystocia
Changes in milk composition close to parturition
Na+ and K+ inversion (use urinalysis panel)
Increase in calcium
How will Na+ and K+ in mild change close to parturition?
Na+ goes down,
K+ goes up
A foal-watch test kit reads a milk Ca++ of over 200 ppm. This indicates that parturition will likely occur within
24-72 hours
With Foal-Watch, assays may be run once daily until Ca++ reaches...then check twice daily.
125 ppm
Confounding variables with milk calcium testing.
Maiden mares may not have significant udder development or colostrum production
Precocius mammary development may occur with placental pathology
Stage of labor ending with rupture of chorioallantois.
Stage I
Stage of labor ending with delivery of the foal.
Stage II
Site where chorioallantois should rupture.
Cervical star
Stage of labor in which mare actively strains.
Stage II
Stage of labor ending with delivery of the placenta.
Stage III
Three signs of normal foal delivery.
White chorioallantois
Feet pointed downward
Nose emerges once cannon bones are out
What is the significance of a "red bag" during foaling?
Premature placental separation and hypoxia-- get foal out ASAP!
How is uterine prolapse treated in the mare? What may it be mistaken for?
Rinse/clean uterus
Push in with palm, extend horns with a bottle in a sterile sleeve
Four causes of placental separation
Fetal death
Severe uterine edema
Reasons to induce a mare to foal.
Gestational abnormalities
Mare with previous dystocia or Hx of planental separation
NOT convenience, ideally!
Possible side effects of induction in mare.
Premature placental separation
Fetal hypoxia
When in the equine pregnancy does fetal maturation occur prepartum?
24-48 hours before birth
Fetal cortisol stimulates production of this hormonal cascade in the mare.
Decrease progesterone/ Increase estradiol
Stimulation of PGF production, decreased oxytocin receptor threshold sensitivity
Why are steroids not usually indicated for induction of equine parturition?
Too unpredictable, require high doses over prolonged period of time
How long foes it take for prostaglandins to result in parturition in the horse?
1-6 hours (variable)
May be used as a pretreatment when inducting equine parturition.
Most common drug used to induce parturition in the mare. How long does it take to work?
Most foalings within 60 mins
Describe proceedure for preparing for an induced equine parturition.
Check repro records to ensure foal is near-term
Milk Ca test
Rectal palpation to check for cervical softening
Transrectal ultrasound to assess placenta
Transabdominal ultrasound to assess fetus
Wrap tail, wash perineum
After administering oxytocin IM to induce parturition, how long before intervention may be indicated? What should be done if no effect seen at this point>
30-45 mins, then repeat exam before administering more oxytocin
How many doses oxytocin maximum should be given to induce a mare on a given day?
If there is no response to the second oxytocin dose when inducing parturition, one should...
Discontinue proceedure, reassess later (tomorrow or later)
How should the umbilicus be treated after foaling?
Dip in 1:4 tincture of nolvasan or in tincture of iodine
After how long should a newborn foal stand and nurse? How long before placenta normally passed?
1 hr= stand
2 hr= nurse
3 hr= pass placenta
Normal number of tears in placenta as examined postpartum.
One, at cervical star
When feeling the placenta post-partum, will the fetal horn or non-fetal horn feel thicker?
Fetal horn
Signs of umbilical torsion include..
Line of demarcation on umbilicus where blood flow ceases
Bladder distension
Mineralization of chorioallantois
How common are lesions of the equine amnion?
Are lesions of the chorioallantois or lesions of the amnion more common in the horse?
Major cause of edematous placenta
Fescue toxicosis