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Therio - Equine Complications 2

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drraythe's version from 2017-09-10 04:02

Non-infectious czs of abortion- Twins, Mare Reproductive Loss Syndrome

Question Answer
(Twins) how common is double ovulation in a mare's cycle?Double ovulation occurs in 5 to 20% of all cycles
How often do twin pregnancies end in abortion?90% of all twin pregnancies will result in abortion
If twins survive to being born, how often are they healthy?90% of all twins born will need additional medical care
What are some problems that happen after abortion from twins?Reduced fertility after abortion, dystocia & retained placenta
Which type of twins are more common, & why?Majority heterozygotic twins (>99%) – ie. Separate oocytes, bc of Double ovulations (synchronous vs. asynchronous)
Is there an age predisposition for twinning to occur?Double ovulation more common in older mares
Breed predisposition for multiple ovulations?Thoroughbreds (15-25%), & Draught (draft) horses (24%) are the most common, followed by Standardbreds (13-15%), Quarter horses & Appaloosas (8-10%), then lastly w/ Domestic ponies (2-3%)
How can hormonal manipulation of the estrus cycle (w/ what drugs) cz inc chance of double ovulation?using PG & hCG, → Increased ovulation rate & increased pregnancy rates
What are the diff ways twins can be arranged in the uterus?
What does a placenta from twins look like? Why does it look this way?Large AVILLOUS area where 2 chorions were adjacent – prevented development of microvilli for nutrition
What is going on in this pic? 1 twin was starving in utero due to inadequate placentation
How can you help in the prevention of twinning?Can only in part be avoided by good management. It is important to note every double ovulation or risk of double ovulation! If a double ovulation is diagnosed/suspected then pregnancy diagnoses planned at 14 days post ov w/ recheck at 16 days.
*If double ovulation has been suspected, what do you do?Pregnancy diagnoses planned at 14 days post ov w/ recheck at 16 days.
Diff btwn synchronous & Asynchronous twins?Synchronous twins = similar size
Asynchronous twins = different sizes. (Sync on L of pic)
What is usually the fate of unilateral twins in nature?Majority reduce to singleton by 40D gestation
What is usually the fate of bilateral twins in nature?Majority will abort in LATE gestation, in some cases, 1 fetus will mummify & the other will continue to term
5 options for Tx of twin pregnancy?(1) Manual crushing of 1 embryonic vesicle
(2) Wait for natural twin reduction (only for unilateral twins)
(3) Transvaginal or transabdominal puncture
(4) Decapitation by flank incision approach
(5) Terminate pregnancy
Manual crushing of 1 embryonic vesicle as a Tx for twins → WHEN is the preferable time to do this? How successful is this type of TX?The earlier the better, preferably during mobility phase. High success rate (>90%)
How do you perform manual crushing of 1 embryonic vesicle?
TX of twins → Transvaginal or transabdominal puncture of fetus → what are you doing during this, how is it done?A small volume of procaine Penicillin is injected in the thorax of the fetus
Mare Reproductive Loss Syndrome is thought to be linked w/ what?Thought to be linked w/ drought & higher than normal temperatures leading to emergence of large numbers of Eastern Tent Caterpillars
What is the theory of the pathogenesis of MRLS?Thought to be "migrating septic penetrating setae"
MRLS is linked to what 2 things?The eastern tent caterpillar & the black cherry tree where the nests are found
4 main CSs of MRLS?(1) Early fetal loss
(2) Pericarditis
(3) Panophthalmitis (inflammation of all coats of the eye inclding intraocular structures.)
(4) Late term abortions
MRLS can cz early fetal loss, OR late term abortions. How does it cz the late term abortions? (2 pathogeneses & then the quality at which the abortion takes place)There will be premature placental separation & also placental thickening which eventually leads to explosive deliveries
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Abnormal Gestational Conditions

Question Answer
When does Mummification/fetal maceration occur in horses?TRICK QUESTION- it doesnt happen bc there is no persistence of CL in horses
Vulvar bleeding prepartum → how does this problem present? Where is the blood coming from?Presents as Discrete to obvious dripping of blood from vulva. This is bc of Varicose veins located at or just caudal of the vestibulo-vaginal folds (pic of arrows pointing to varicose veins)
Vulvar bleeding prepartum usually occurs when, & is this bleeding dangerous for the mare?Can start a few days to weeks before foaling, is NOT life threatening to the mare
What are 3 things you can do to Tx vulvar bleeding prepartum?(1) Do nothing
(2) Cauterize
(3) Silver nitrate
What should you NOT do in an attempt to Tx vulvar bleeding prepartum?Do NOT ligate!! Veins are too fragile & will rupture at ligation site
WHEN does uterine torsion most often occur for horses? (Compared to cows?)In mares most frequently in last 3 mos of gestation (rarely if ever at the time of foaling vs cows)
How does uterine torsion usually present in the mare?Mild, chronic colic but no gastrointestinal abnormalities
What are the 2 main problems that uterine torsion can cz?Risk for fetal hypoxia & uterine necrosis
*How can you Dx uterine torsion? (What do you do?)Verify the orientation of the broad ligaments! do this by Performing rectal palpation → Will feel tight “band” across dorsum of uterus (Direction of band indicates direction of torsion)
How is surgical repositioning performed on a mare w/ uterine torsion?Performed on the standing mare! Flank incision to allow passage of arm → Incision on left for counterclockwise (towards the left) rotation (so make incision on side that the uterus has rotated towards) → “Lift” the uterus up & flip back into the normal position. Finally, verify the broad ligaments to confirm correct position
What non-surgical procedure can you try to derotate a uterine torsion?Plank in the flank-- Mare placed on the side TOWARDS which the uterus has rotated: Ie. Rectal palpation indicated taut right broad ligament, therefore uterus has rotated TOWARDS the left, so Mare placed in left lateral recumbency (laying w/ left side down) & rolled over.
Pic for the setup of the plank in the flank procedure for uterine torsion if the mare's uterus had rotated to the left?
What is it about fescue that czs fescue toxicity?Tall fescue grass infected w/ an endophyte fungus Acremonium coenophialum which secretes ergot alkaloids & these alkaloids are what cz all the problems bc they act as Dopamine agonists/prolactin antagonists
What problems do ergot alkaloids cz, & WHY are they harmful?They act as Dopamine agonists/prolactin antagonists which Suppresses prolactin & Czs agalactia ((remember prolactin plays a role in the mare's cycle
What kinda repro probs does the fescue tox (ergot alkaloids) cz? (6)(1) Prolonged gestation
(2) Oversized fetus & dystocia
(3) Abortion
(4) Thickened placenta, placental insufficiency
(5) Fetal asphyxiation
(6) Premature separation of placenta (“red bag delivery”)
How can you help prevent fescue tox? (4)(1) Maintain pregnant mares on non-fescue pastures
(2) Dilute the toxin by overseeding pastures w/ palatable legumes
(3) Kill infected pastures & reseed w/ endophyte resistant strains of fescue
(4) Remove mares from fescue pastures during last 90 days of gestation
What are the 2 drugs used to Tx fescue tox?(1) Domperidone (dopamine receptor antagonist)
(2) Sulpiride
What is domperidone? What is it used to Tx?It is a dopamine receptor antagonist used to treat fescue tox (bc the ergot alkaloids act as dopamine agonists) (0.5 mg per lb once daily starting minimum 10-15 days prior to due date, Continue after foaling if mares are not producing adequate milk)
What is Sulpiride? What is it used to Tx?Selective dopamine antagonists, used to treat fescue tox
What are the 2 hydrops conditions?Hydramnion or hydrallantois
Who is more prone to hydrops conditions? (How common is it in general?)Occasionally encountered – more Draft horses
Where does the pathology of hydrops conditions occur?Pathology at the level of the placenta or fetus
How is the mare's future fertility affected by hydrops conditions?It’s not affected :)
How do hydrops conditions affect the foal?Foal is not viable :(
What problem do hydrops conditions predispose to?Rupture of prepubic tendon
How do you go about treating hydrops conditions?Very slowly (over hours) remove excess fluid w/ transcervical catheter. Watch for hypovolemic shock → Induce parturition w/ Oxytocin after the larger part of fluid has been evacuated. → Assist w/ delivery bc the overstretched uterus may have poor contractility
How does ruptured prepubic tendon present?Wide based stance w/ depressed back, loss of ventral abdominal support
How big of a problem is prepubic tendon rupture?Very painful - life-threatening
Why does prepubic tendon rupture lead to problems during parturition?No abdominal press during parturition
How is the mammary gland affected by prepubic tendon rupture?Mammary gland often involved in trauma (no or insufficient milk)
How do you Tx prepubic tendon rupture?Permanent lesion that cannot be repaired surgically → If able to survive, should not carry foal in future
How does prepubic tendon rupture affect mare's ability to be preg?If able to survive, should not carry foal in future!!
Abdominal hernias-- how much of an emergency is this? How painful? How does this affect mare's ability to get preg?Not life threatening – not painful – can become pregnant again
How is an easy well to tell extreme ventral edema from a prepubic tendon rupture?Ventral edema is NOT PAINFUL & tendon rupture is super painful
How do you Tx ventral edema?Mild exercising the mare will stimulate circulation & lymph drainage, Resolves spontaneously after foaling (w/in 1-2 days)
CQ: How long does involution take?12-14d
CQ: Prolonged interestrus prolly means what happened?EED
CQ: When in gestation does ascending Placentitis usually take place? What other sign will you see not related to the placenta?Ascending Placentitis is in late gestation (& youll see mammary development & mare is not sick)
CQ: When in gestation does Mare reproductive loss syndrome occur?Late gestation
CQ: Liver spotting/necrotic foci on dead & aborted fetus?EHV1
CQ: What do you usually see w/ fetus/mare?Fetus icteric & mare is sick
CQ: Which 2 infectious dzs will you see the mare is sick?Babesia & lepto
CQ: Large avillous spot on placenta- prolly what?Twins
CQ: Are there pathognomonic signs for fescue tox?No (maybe a bit of thickening?)
CQ: If you see mammary development in mid-gestation what are you thinking?Prolly impending abortion
CQ: Abortion storm on TB stud farm. Resp symptoms & ventral limb & mammary edema. What do you think?Most likely equine viral arteritis virus (ventral limb edema unique to this, Herpes is resp symptoms also along w/ arteritis)
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