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306 Cards in this Set
- Front
- Back
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When during the estrus cycle does ovulation occur in the mare?
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24-48 hours before end of estrus.
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When is the ideal time to breed a mare in relation to her estrus cycle?
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Right after the peak in estrogen, as evidenced by maximal uterine edema per ultrasound
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What about the mare's LH release is unique in comparison to other species?
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Broad based LH curve, rather than a spike like other species
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What is unique about the anatomy of the equine ovary?
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All ovulations through the ovulation fossa.
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These structures stimulate formation of secondary CL's to help maintain pregnancy from day 40-120.
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Endometrial cups
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The equine pregnancy is CL dependent until what point in gestation? Why?
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Around day 100 as the fetus begins secreting its own progestagens
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What hormone is secreted by the endometrial cups? What does this hormone do?
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eCG, stimulates production of secondary CL's to secrete additional progesterone.
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This hormone rises in the pregnant mare from day 80, then gradually declines after day 200.
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Estrogen
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This hormone peaks just before parturition and falls right at time of delivery.
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Progesterone
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How long is the AVERAGE equine gestation?
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343 days, or 11 months
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Foal heat occurs this long after parturition.
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7-14 days (average 9-10)
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If a mare is bred on her foal heat, she will be more fertile this many days after parturition. Why?
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Day 9... Gives uterus time to clean out.
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The mare's breeding calendar may be advanced by one month each year if she is bred before...
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Day 25 post-partum
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List some signs of estrus in the mare.
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Urination
Ears not back Winking vulvar lips Posture Tail raised |
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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?
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Short cycle with prostaglandins
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List some ways in which exogenous progestins may be administered.
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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 |
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Why can't progesterone implants be counted on to maintain pregnancy?
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Less reliable distribution b/c SQ
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How would one manipulate lighting to start the transition cycle of the mare? Include time intervals.
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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. |
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If you want a mare to go into a fertile estrus around February 15th, when would you begin putting her under artificial light?
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Decemebr 15th.
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This hormone suppresses production of GnRH in the mare.
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Melatonin
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What stimulates production of melatonin in the mare?
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Increased darkness
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For how long would altrenogest be given to shorten the transition period in the mare? Then what else is given?
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9-14 days, then give prostaglandin to lyse CL
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This dopamine antagonist has been used with mixed success to shorten the transition period in the mare to 14-21 days.
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Domperidone
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The size of an ovulatory follicle in a mare is roughly...
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30-35 mm
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List three compounds that are effective at maintaining an equine pregnancy.
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Progesterone in oil IM qd
Regumate po qd BioRelease P4 LA (IM at 10-14 day intervals) |
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How does progesterone aid in pregnancy maintenance?
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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 |
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List some drugs that may be given to help halt an impending abortion in the mare
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Altrenogest po qd X 2
Progesterone in oil IM qd Banamine bid po/iv Pentoxyphiline bid Tocolytics to (-) smooth muscle contraction |
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How can ovulation be postponed pharmacologically?
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Oral progesterone given for 3 days, delays LH peak by 1.5 days
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What is the downside of using progesterones to delay ovulation?
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Could increase incidence of anovulatory follicles
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This hormone inhibits LH secretion.
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Progesterone
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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?
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Progesterone and estrogen for 10 days, then give PGF on day to lyse CL. Ovulation on day 21.
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Major form of estrogen in criculation, generated by fetus and placenta.
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Estrone sulfate
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Used as a hormonal marker of pregnancy after day 80 or so.
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Estrone sulfate
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What is the possible function of estrogens during gestation?
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Luteotropic, responsible for maintaining secondary CL's.
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What hormonal changes would indicate either impending parturition or abortion in the mare?
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Progesterone spike
Drop in estrogen |
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When deslorelin is used to induce ovulation, how long before it occurs?
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Ovulation in 38 +/- 2 hours
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How is hCG used to stimulate ovulation in the mare if she is being bred by AI?
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Give hCG, ovulation occurs 24-48 hours later.
Breed at 24 hrs and 40 hrs. |
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What are some concerns with use of hCG to ovulate an aged mare?
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Less effective, maybe due to receptor issues or antibody effects.
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What would be best to ovulate an older mare at the end of the season, and why: deslorelin or hCG?
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Deslorelin: Tighter ovulation window, and hCG associated with less efficacy in older mares.
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In the spring transition period, which gonadotropin is produced first by the pituitary?
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FSH
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When attempting to ovulate a mare in the transitional period, would deslorelin or hCG be more effective, and why?
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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.
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What undesirable pregnancy side effect is associated with hCG use?
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Double ovulations and twinning
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List the two physiologic responses to oxytocin.
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Milk letdown
Uterine contraction |
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How can oxytocin be given to suppress estrus in the mare?
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Dose bid on days 7-14 AFTER ovulation, and will maintain CL beyond 40 days
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How can ocytocin be given to help prevent a post-partum metritis.
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6 hrs apart on day 1
4 hours apart on day 3 |
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The effects of prostaglandins
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Contraction of smooth muscle
Lysis of CL |
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Which ecbolic will produce a more prolonged contraction of smooth muscle: oxytocin or prostaglandin?
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Prostaglandin
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Natural prostaglandin drug name and brand name
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Dinoprost tromethomine, aka Lutalyse
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Synthetic prostaglandin drug name and brand name.
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Cloprostenol, aka. Estrumate
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How can the dose level and administration timing of prostaglandins be modified to reduce side effects?
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1/10 normal dose for 2 days in a row
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If short cycling a mare with prostaglandins, how long after ovulation must you wait?
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5-6 days
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When is prostaglandin used to manipulate uterine tone for reduction of post-breeding metritis?
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Use prior to ovulation
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Why should PGF not be given to a mare after ovulation to prevent metritis?
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Decreases progesterine concentration and reduces pregnancy rate.
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When is prostaglandin used to manipulate uterine tone for reduction of post-breeding metritis?
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Day of ovulation, to post-ovulation
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What are some side effects of PGF administration in the mare?
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Sweating, colic, inappetance, lasting 15-20 mins
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How is isoxsuprine used to preserve a pregnancy? Low long does it last?
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Tocolytic, stops uterine contractions, lasts 1-2 hours
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Why should isoxsuprine not be used in a mare in near-term pregnancy?
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SE to foal: Tachycardia, hypoglycemia, hypocalcemia, ileus, hypotension
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Clenbuterol is used for this purpose in a pregnant mare.
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Tocolytic, stops uterine contractions to halt impending abortion.
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This tranquilizer decreases myometrial activity.
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Acepromazine
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These two tranquilizers increase myometrial activity.
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Detomidine
Xylazine |
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Why would dexamethosone or prednisolone be given around the time of breeding?
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Decrease uterine fluid accumulation to improve fertility and reduce incidence of post-mating metritis.
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What are some major effects of fescue toxicosis in the pregnant mare?
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Agalactia
Prolonged gestation Increaded placental weight Retained placenta Premature separation Dystocia Poor neonatal viability EED |
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How does fescue toxicosis affect progestogen concentrations in the mare?
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Lower in affected mares
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When should broodmares not be exposed to fescue?
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During spring transition (delayed cyclicity)
First 30-60 days gestation Last 30-60 days gestation |
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Once a mare is removed from fescue, how long will it take for her progestogen levels to increase?
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3-5 days
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Drug used to increase prolactin in the event of fescue toxicosis.
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Domperidone
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What is the therapeutic use of reserpine in the pregnant mare?
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Calms mare and boosts milk production
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Possible side effects of reserpine.
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Diarrhea
Neurologic effects |
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How does bromocriptine work? Why is it used?
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Dopamine antagonist, used for treatment of Cushing's disease.
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What is an undesirable effect of using bromocriptine in a cushingoid broodmare?
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Decreased cyclicity, decreased milk production.
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In a pregnant mare being treated for Cushing's disease with bromocriptine, when should the drug be stopped?
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One month prepartum, +/- add domperidone
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What is the "doubling rate" when evaluating stallion records?
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Related to proportion of mares bred to that stallion more than once per cycle.
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Is the pregnancy rate for a given stallion higher or lower early in the breeding season?
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Higher--> Most females get bred in 1st 2 cycles, and the "problem" mares are the ones trying to get bred late in season.
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Number of mares pregnant divided by total number of mares bred for the season.
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Seasonal pregnancy rate
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Number of cycles per season divided by number of pregnancies. Measure of the efficiency of the stallion at establishing pregnancy.
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Pregnancy rate per cycle
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What is the significance of the "doubling rate" for a stallion? Why does it matter?
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Excessive covers or inseminations per cycle can result in overuse of a stallion and semen wastage.
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Is the typical book size of a typical high-performing stallion increasing or decreasing over the years?
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Increasing
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The average stallion has a book size of...mares per season.
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15
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How do you establish a stallion's DSO?
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Collect him daily for 5-7 days to deplete extragonadal sperm reserves so that only one day's worth of semen is ejaculated.
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What are some management factors that can affect stallion fertility?
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Frequency of collection/breeding
Medications (steroids, progesterone, etc) Housing (near mares, stallions, alone, etc) Lighting? Heat decreases sperm output |
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Why is exercise important for a breeding stallion?
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Lack of exercise can result in behavior abnormalities
Strong legs, back, and good physical condition Keep stalion alert, athletic, and content |
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This is the term for a stallion, often a shielded scrub pony, used to gauge mare receptivity.
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Teaser stallion
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Why are teaser stallions used?
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Gauge receptivity of mares to minimize risk of injury to a more valuable breeding stallion
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These barriers may be used when teasing a mare to determine estrus.
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Mare in stall
Mare in stocks Across teasing "wall" Across phantom |
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What are some reasons that a mare may not be bred naturally?
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Repro tract abnormality
Lameness, neurologic issue Owner preference Mare not receptive, even in estrus |
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Describe the testing protocol for EVA in a stallion.
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Test stallion via serology
If negative--> vaccinate If positive--> Culture semen If semen positive--> Vaccinate mare |
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True or false: There is no risk of sexual transmission of EIA.
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False.
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List the basic components of a mare BSE.
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Physical exam and history
Conformation evaluation Rectal palpation Ultrasound evaluation Vaginal speculum exam Culture, cytology, biopsy |
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When in a mare's cycle should uterine culture be done?
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Diestrus or early estrus
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True or false: A fair number of mares can culture positive on uterine swab from contamination through the open cervix during estrus.
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True
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List three barriers to infection in the mare's repro tract.
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Vulva
Vestibulo-vaginal fold Cervix |
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During this stage of the mare's cycle, there is increased immunity in the uterus and decreased mechanical protection.
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Estrus
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During this stage of the mare's cycle, there is decreased immunity in the uterus and increased mechanical protection.
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Diestrus
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Does a failure of immunologic or mechanical clearance tend to cause problems more commonly in the mare?
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Mechanical
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What concerns could there be with breeding a maiden 15 year old mare?
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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.
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How long does it normally take a mare to eliminate uterine fluid following a challenge/mating?
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Several hours
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A normal mare should be able to clear bacteria from the uterus in...
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36-48 hours
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A mare is more susceptible to post breeding endometritis when she has one of the following factors:
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Poor uterine defense mechanisms
Delayed uterine clearance Poor uterine position Unable to eliminate bacteria by 96 hours Multiparous or older mared |
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How often should a "susceptible" mare be ultrasounded following breeding to ensure uterine clearance?
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Intervals of 12-24 hours (Should be clear in 24 h)
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True or false: Fluid in the uterus after breeding is a key sign of post-mating endometritis.
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False
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How long after breedig should the practitioner wait to do a uterine lavage, and why?
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4 hours-- gives time for the oviductal epithelium to become saturated with sperm
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How much fluid may be found in the mare's uterus after breeding before the DVM should be concerned?
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Up to 2 cm
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What are some downsides to doing a uterine lavage for cytology?
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Time consuming
May cause inflammation Requires sedimentation/centrifugation |
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This uterine swab has a single head for culture and a cap for collecting cytology samples.
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Kalayjian swab
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This uterine swab prevents accidental swab contamination by using outer and inner sleeves
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McCullogh swab
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Stain used to visualize vaginal cytology smears.
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DiffQuik, aka Modified Wright's Stain
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Normal biopsy grade, 80-90% exprected foaling rate
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Grade I
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Biopsy grade: Mild change, 50-80% expected foaling rate
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Grade IIa
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Biopsy grade: Moderate change, 10-50% expected foaling rate
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Grade IIb
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Biopsy grade: Severe change, Under 10% expected foaling rate
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Grade III
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Why is the distribution of uterine glands a good predictor of expected foaling rate?
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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.
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On what day of gestation does the embryo enter the utero-tubal papilla?
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5-6
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List some ways to determine oviductal patency.
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Presence of embryo
Starch granule test Fluorescent labeled beads (flow cytometry) Flush oviduct surgically through the flank |
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List three reasons a mare may become infertile.
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Non-cyclic
Failure to concieve Embryonic loss |
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If a pregnancy is lost between days 40 and 120, why is the mare likely "lost" for the season?
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Endometrial cups persist and stimulate progesterone production up through day 100-120 regardless of whether the mare is still pregnant.
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List some reasons for a non-cyclic mare.
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Not bred b/c not found in heat
Pregnancy Retained endomertial cups Prolonged diestrus/pseudopregnancy Gonadal dysgenesis Out of season GTCT Behavioral anestrus Ovarian shutdown |
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Occurs when the CL lifespan is prolonged beyond 15 days.
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Prolonged diestrus/pseudopregnancy
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List some reasons for a prolonged diestrus or pseudopregnancy.
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Diestral ovulation (immature CL not responsive to PGF when released)
EED after maternal recognition Failure of PGF release due to uterine abnormality Luteal cyst |
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How would prolonged diestrus due to a luteal issue be resolved?
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Donoprost, exogenous PGF
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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?
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Gonadal dysgenesis due to chromosomal abnormality
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This pseudohermaphrodite is genetically female and has a penis where the clitoris would be. More common of the two types.
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Male pseudohermaphrodite
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This pseudohermaphrodite is genetically male, has ambiguous-to-male external genitalia, and ovaries.
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Female pseudohermaphrodite
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Most common type of ovarian tumor in the horse.
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Granulosa-theca cell tumor
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What hormonal tests would help to screen for a granulosa cell tumor?
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Inhibin and testosterone
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Why, in the event of a granulosa cell tumor, would the opposite ovary be very small?
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Tumor secreting inhibin
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What is the treatment for a granulosa cell tumor, and how long before the mare cycles normally?
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Remove affected ovary and other one should resume cycling soon, based on the time in the season when Sx done. Average of 8 months.
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What factors could drive a mare into behavioral anestrus?
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Novel environment
Too familiar with stallion Dislikes stallion Maiden mare Mare with foal |
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How can a mare in behavioral anestrus be brought around?
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Careful teasing, frequent palpation, PGF to synchronize estrus, AI or restraint for breeding
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This condition is similar to cystic ovarian disease in cattle, leading to increased progesterone production.
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Anovulatory follicle
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Mares tend to undergo reproductive senescence around age...
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25 years
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List some reasons for ovarian shutdown in the mare.
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Anolvulatory follicle
Reproductive senescence Negative energy balance Anterior pituitary dysfunction |
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How can a luteal cyst be treated in the mare?
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Dose with PGF
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How can a follicular cyst be treated in the mare?
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No Tx: Wait for it to luteinize (80% will) then give PGF.
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Inflammation of the inner layer of the uterus
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Endometritis
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Why is post-mating endometritis such a cause for worry?
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Associated inflammation after embryo in uterus may cause PGF release and luteolysis, or directly affect embryo.
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Mucus in uterus is secreted by the...
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Endometrium
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How will uterine mucus production change with acute infection?
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Increase
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How will uterine mucus production change with chronic infection?
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Decrease
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List some commonly used biofilm-mucus disruptors.
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DMSO
N-acetylcysteine |
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What kind of semes in most commonly associated with post-breeding endometritis?
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Frozen semen
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Why is frozen semen more frequently associated with an exaggerated inflammatory response than is fresh semen?
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Seminal fluid seems to decrease inflammatory response
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Why is seminal plasma often removed from frozen semes samples-- besides to save space?
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Seminal fluid shortens sperm lifespan, activates sperm.
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List two equine veneral diseases that may cause endometritis.
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CEM
EVA |
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How is endometritis treated?
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Lavage
Augment uterine clearance with ecbolics Local or systemic Abx as needed Return to estrus QUICKLY to open cervix and (+) immune system |
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List three ways in which the mare's genital barriers may be made more effective.
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Vulvoplasty (Caslick's)
Urethral extension Cervical repair |
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True or false: Warm uterine lavage stimulates uterine contraction.
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True
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Would lactated RIgner's solution or normal saline be a better choice for uterine lavage, and why?
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More physiologic pH, less irritating
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This ecbolic may be administered as soon as 4 hours after mating to speed uterine clearance.
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Oxytocin
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This ecbolic may not be given on or after the day of ovulation to speed uterine clearance.
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Prostaglandin
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Chronic degenerative endometritis due to wear and tear on uterus over time.
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Endometrosis
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Endometrosis is more commonly seen in mares of this age
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13-14 years or older
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This degenerative reproductive disease is marked by fibrosis, lymphatic stasis, uterine sacculation, adhesions, diverticuli, and endometrial/lymphatic cysts.
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Endometrosis
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How may endometrosis be treated?
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No specific, reliable reversal.
Mechanical currettage, biopsy Laser Electrocautery Hypertonic saline DMSO Magnesium sulfate Hydrogen peroxide Kerosene |
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What is the goal of endometrosis treatment?
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Inducing superficial endometrial inflammation, necrosis, and loss of damaged tissues
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List some of the benefits attributed to DMSO.
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Activate complement
Aid PMN opsinization Decrease inflammatory damage Reduce endometrial fibrosis |
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When does metritis usually occur in the mare?
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Post-partum
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Massive contamination of the uterus with or without trauma
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Metritis
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List a major cause of sustemic illness from metritis
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Gram negative organisms--> Endotoxemia
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How does metritis differ from endomertitis?
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Metritis: Deeper uterine layers affected
Endometritis: Only endometrium inflammed. |
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True or false: Metritis is a medical emergency in the mare.
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True
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True or false: A mare with pyometra most often shows no clinical signs.
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True
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When signs of pyometra are noticed, they typically include:
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Pain on performance from weight of uterus
Vulvar discharge |
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Pyometra is associated with which ovarian structure?
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CL
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What is the prognosis for future fertility once a mare has has pyometra?
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Poor due to endometrial damage and cervical pathology
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How is pyometra treated in the mare?
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*R/O PREGNANCY 1st!*
PGF to lyse CL Drain large volumes slowly Uterine lavage with ecbolic Systemic antibiotics |
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List some anatomical incompetencies that may cause infertility in the mare.
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Cervical incompetence
Cervical adhesions Rectovaginal fistula Perineal body incompetence |
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List some factors that may affect oocyte quality.
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Age of mare
Age of oocyte since ovulation (deteriorates after 8-12 hrs) Nutritional status of mare |
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What does it mean for a mare to be subfertile?
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She can conceive but cannot maintain a pregnancy due to EED.
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Lack of uterine glands can decrease production of
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Histotroph
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Early embryonic death takes place before
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Day 45
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Abotrion occurs when the fetus is expelled between
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Organogenesis (day 45) and survivability (day 300)
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Foal born prior to 320 days gestation
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Premature foal
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Foal who has signs of prematurity, but was born after 320 days gestation
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Immature foal
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Immature foal associated with placentitis or ammonitis.
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Dysmature foal
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Foal born after 365 days gestation
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Postmature foal
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List some factors affecting embryonic loss in the mare.
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Major stress
Nutrition Seasonal and climatic factors Maternal age Lactation and foal-heat breeding |
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How would you go about trying to pinpoint the cause of an abortion?
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Examine fetus internally/externally
Serum from mare Examine placenta, especially near cervical star Weigh placenta TIssue samples from blood-filtering organs |
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List three routes of placental infection.
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Transcervical
Hematogenous Previous intrauterine infection |
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How can you tell if abortion occurred as a result of transcervical infection?
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Look at the cervical star to see if there is purulent material, scarring, etc.
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Common bacterial cause of abortion.
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Streptococcus zooepidemicus
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If an abortion is due to bacterial infection, how will the placenta appear?
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Purulent
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If an abortion is due to viral infection, how will the fetus appear?
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Fresh
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List some non-infectious causes of abortion.
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Twinning
Twisted umbilical cord Uterine body pregnancy Trauma Treatments Nutrition Endocrine dysfunction Extensive uterine fibrosis Endometrial cysts Endometrial atrophy |
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List some ways in which abortion may be induced in the mare.
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Prostaglandins (multiple injections, especially before day 90 but all through)
Manual cervical dilation with fingers Anthelmintics Nutrition (poor nutrition or fescue) |
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What kind of twins are more common in the equine: monozygotic or dizygotic?
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Dizygotic
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Do most equine dizygotic twinning events result from synchronous or asynchronous ovulations?
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Asynchronous (over 24 hours apart)
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Why are asynchronous ovulations possible in the equine?
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Broad-based LH curve
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What feature of the equine embryo prevents pinching and monozygotic twinning?
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Capsule
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Twinning is more frequent in these breeds of horse.
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Thoroughbred and draft mares
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Are twins more frequent in older mares (6-10) or younger mares (2-5)?
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Older
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What is the most frequent outcome of a twin pregnancy?
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Birth of a single foal
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How frequently are both twins lost in the equine twin pregnancy?
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31% of the time
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How frequently are both twin foals born alive?
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1% of the time
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At what point in the pregnancy can a twin pregnancy be diagnosed per ultrasound?
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Day 14-16
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What event occurs at day 16 of the equine pregancy?
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Fixation (embryo sticks to uterine wall)
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Why should twin elimination occur ideally before fixation at day 16 of pregnancy?
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It is difficult to crush only one embryo if both are fixed in close proximity.
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How can natural reduction of a twin pregnancy occur after fixation?
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Orientation of twin vesicles within uterine lumen--> Less placental contact and nutrient deprivation of one twin
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Is natural reduction of a twin pregnancy more likely with a unilateral or bilateral fixation of embryos?
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Unilateral
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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.
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Type A.
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Describe the kind of twin placentation in which both fetuses are of equal size and both in the uterine body.
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Type B
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Describe the type of twin placentation in which one twin is undergoing mummification and one is alive.
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Type C
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Most common form of twin reduction.
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Ultrasouns assisted crushing
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When is ultrasound-assisted crushing of a twin vesicle best done?
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Prior to day 16
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Type of fetal reduction more commonly done after fixation.
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Aspiration
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What is the major risk associated with fetal aspiration?
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Reduction of both embryos
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What is the success rate of fetal cranio-cervical dislocation?
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71% success, but 30% need to be repeated 10 days later
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How long does it take for the fetal heartbeat to stop following cranio-cervical dislocation?
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1-3 weeks
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At what point in gestation is cranio-cervical dislocation done?
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60-110 days gestation
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Intra-cardiac perfusion with this drug is commonly done to reduce a twin.
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Procaine penicillin
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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?
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Prostaglandin
Return to estrus in 5-7 days |
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After day 35 of gestation, how may a mare be aborted with drugs?
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Prostaglandins, multiple shots over 3-5 days
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Late natural reduction may occur up to this point in the equine pregnancy.
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Day 60
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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...
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Mummification
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Death of a fetus with bacterial contamination results in...
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Maceration
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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.
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Hydrops allantois
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Clinical signs associated with hydrops allantois.
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Reluctance to move, altered gait, and dyspnea
Rapid distension over 10-14 days |
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What is the treatment for hydrops allantois?
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Induce abortion, manually dilating cervix and puncturing membranes
Give oxytocin and run IV fluids |
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Possible complications of hydrops allantois.
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Hyopvolemic shock after delivery
Ruptured prepubic tendon, herniation, abdominal muscle rupture, uterine rupture |
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Slow accumulation of amniotic fluid over weeks to months.
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Hydrops amnii.
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Which condition occurs more frequently in the mare: hydrops allantois, or hydrops amnii?
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Hydrops allantois
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How is prepubic tendon rupture addressed in the mare? What is the prognosis?
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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 |
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What anatomical feature makes uterine torsion rare in the horse?
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Dorsal uterine attachment of broad ligament
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When in gestation does uterine torsion occur?
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Months 5-10
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Clinical signs of uterine torsion in the mare.
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None, to colic, restlessness, frequent urination
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How is a diagnosis of uterine torsion made?
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Rectal palpation
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When correcting a uterine torsion, should the mare be twisted in the direction of the torsion or the opposite way?
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Direction of the torsion
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Cause of slight recurrent vaginal bleeding in older multiparous mares late in gestation.
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Vaginal varicose veins.
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How are vaginal varicose veins treated in the mare?
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Ligation, cautery, or laser ablation if severe
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Usually a result of mutation and fetotomy or violent intrapartum movements in the mare.
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Uterine rupture
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How is a diagnosis of uterine torsion made?
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Rectal palpation
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When correcting a uterine torsion, should the mare be twisted in the direction of the torsion or the opposite way?
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Direction of the torsion
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Cause of slight recurrent vaginal bleeding in older multiparous mares late in gestation.
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Vaginal varicose veins.
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How are vaginal varicose veins treated in the mare?
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Ligation, cautery, or laser ablation if severe
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Usually a result of mutation and fetotomy or violent intrapartum movements in the mare.
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Uterine rupture
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Major cause of prolonged gestation in the mare.
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Fescue
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How does photoperiod affect equine gestation length?
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10 days longer in early spring than in mid summer
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At what point is an equine gestation considered prolonged?
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After 360-380 days
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True or false: The equine fetus may undergo developmental arrest in early pregnancy for several weeks.
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True
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What should be done about prolonged gestation in the mare?
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Try to wait for normal parturition.
Rule out possible inciting causes |
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Low levels of this hormone result in agalactia.
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Prolactin
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Possible effects of fescue toxicosis in the mare include:
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Decreased milk
Prolonged gestation or abortion Weak or dead foals Dystocia Thickened placenta |
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Drug used to treat fescue agalactia.
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Domperidone
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Mares should be removed from fescue at what point in gestation?
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30-45 days before due date
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How long before parturition does a thickened placenta occur as a result of fescue toxicosis?
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48 hours prepartum
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Reasons a mare may be considered to have a high-risk pregnancy.
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Previous gestational problems
Previous health problems with abdomen or pelvis Owner preference |
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What kind of control does the equine fetus have over oxygen delivery to the uterus?
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None
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Initial fetal response to hypoxia.
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Decreased CO, vasoconstriction, increased umbilical vein resisitance.
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If fetal hypoxia persists, how will the fetus respond physiologically?
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Tachycardia and loss of fetal activity
Then terminal bradycardia |
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This hormone causes the relaxation of the tail head ligaments.
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Relaxin
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What is the significance of a decrease in estrogen mid gestation?
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Impending abortion/premature delivery
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When would a transabdominal ultrasound be indicated in the high-risk pregnant mare?
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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 |
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How should amniotic fluid appear on ultrasound?
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Anechoic, small amount of debris if fetus is motile
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Five things to evaluate on a transabdominal ultrasound if there is a high-risk preganancy.
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Character of fluid
Fetal movement Fetal tone Fetal breathing movement Maximal amniotic/allantoic fluid pocket depths |
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How should the depth of the amniotic fluid compare to that of the allantoic fluid?
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Amnion = 1/2 allantoic fluid
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What should be done if a fetus is bradycardic on ultrasound?
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Check back in 1-2 hours, correlate with fetal movement
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Baseline fetal heart rate in late gestation
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60-75
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Which is more common in the fetus: bradycardia or tachycardia?
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Bradycardia common, ominous if consistent
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How does fetal heart rate change with gestational age?
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Decreases as fetus matures
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How thick may the uteroplacental unit fougly appear on ultrasound?
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<2 cm
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Is the placenta thicker per ultrasound in the fetal horn or non-fetal horn?
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Non-fetal horn
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List some ways in which fetal size may be evaluated per ultrasound
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Biparietal diameter/ head width
Orbital diameter |
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If there is clotted blood in the umbilicus on ultrasound, what does this mean?
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Dead fetus
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What is CTUP?
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Combined thickness of uterus and placenta (assumed to be measured transrectally)
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Normal CTUP for days 301-330 gestation
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Under 10 mm
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Where should CTUP be measured?
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At cervical star
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Anatomical landmark for finding cervix on ultrasound
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Middle uterine artery
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Estrone sulfate level is high after this point in gestation.
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60-90 days
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What does a high estrone sulfate reading in an at-risk pregnant mare tell you?
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Foal was alive at least a couple days ago
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Hormone is consistently increased in mares with advanced placentitis
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Progesterone
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List some of the best predictors for readiness of birth.
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Udder formation, presence of colostrum
Increase in milk calcium content Relaxation of cervix Gestational age of over 330 days |
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How soon before parturition does waxing tend to occur?
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1-2 days prepartum
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Consequences of an un-relaxed cervix
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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 |
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Changes in milk composition close to parturition
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Na+ and K+ inversion (use urinalysis panel)
Increase in calcium |
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How will Na+ and K+ in mild change close to parturition?
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Na+ goes down,
K+ goes up |
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A foal-watch test kit reads a milk Ca++ of over 200 ppm. This indicates that parturition will likely occur within
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24-72 hours
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With Foal-Watch, assays may be run once daily until Ca++ reaches...then check twice daily.
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125 ppm
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Confounding variables with milk calcium testing.
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Maiden mares may not have significant udder development or colostrum production
Precocius mammary development may occur with placental pathology |
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Stage of labor ending with rupture of chorioallantois.
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Stage I
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Stage of labor ending with delivery of the foal.
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Stage II
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Site where chorioallantois should rupture.
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Cervical star
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Stage of labor in which mare actively strains.
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Stage II
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Stage of labor ending with delivery of the placenta.
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Stage III
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Three signs of normal foal delivery.
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White chorioallantois
Feet pointed downward Nose emerges once cannon bones are out |
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What is the significance of a "red bag" during foaling?
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Premature placental separation and hypoxia-- get foal out ASAP!
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How is uterine prolapse treated in the mare? What may it be mistaken for?
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Epidural
Rinse/clean uterus Lube Push in with palm, extend horns with a bottle in a sterile sleeve |
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Four causes of placental separation
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Placentitis
Torsion Fetal death Severe uterine edema |
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Reasons to induce a mare to foal.
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Gestational abnormalities
Mare with previous dystocia or Hx of planental separation NOT convenience, ideally! |
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Possible side effects of induction in mare.
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Dystocia
Premature placental separation Fetal hypoxia Dysmaturity |
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When in the equine pregnancy does fetal maturation occur prepartum?
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24-48 hours before birth
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Fetal cortisol stimulates production of this hormonal cascade in the mare.
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Decrease progesterone/ Increase estradiol
Stimulation of PGF production, decreased oxytocin receptor threshold sensitivity |
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Why are steroids not usually indicated for induction of equine parturition?
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Too unpredictable, require high doses over prolonged period of time
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How long foes it take for prostaglandins to result in parturition in the horse?
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1-6 hours (variable)
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May be used as a pretreatment when inducting equine parturition.
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Prostaglandins
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Most common drug used to induce parturition in the mare. How long does it take to work?
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Oxytocin
Most foalings within 60 mins |
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Describe proceedure for preparing for an induced equine parturition.
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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 |
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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>
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30-45 mins, then repeat exam before administering more oxytocin
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How many doses oxytocin maximum should be given to induce a mare on a given day?
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Two
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If there is no response to the second oxytocin dose when inducing parturition, one should...
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Discontinue proceedure, reassess later (tomorrow or later)
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How should the umbilicus be treated after foaling?
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Dip in 1:4 tincture of nolvasan or in tincture of iodine
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After how long should a newborn foal stand and nurse? How long before placenta normally passed?
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1 hr= stand
2 hr= nurse 3 hr= pass placenta |
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Normal number of tears in placenta as examined postpartum.
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One, at cervical star
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When feeling the placenta post-partum, will the fetal horn or non-fetal horn feel thicker?
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Fetal horn
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Signs of umbilical torsion include..
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Line of demarcation on umbilicus where blood flow ceases
Bladder distension Mineralization of chorioallantois |
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How common are lesions of the equine amnion?
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Uncommon
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Are lesions of the chorioallantois or lesions of the amnion more common in the horse?
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Chorioallantois
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Major cause of edematous placenta
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Fescue toxicosis
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