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Theriogenology > Periparturient Period of the Mare > Flashcards

Periparturient Period of the Mare Flashcards

1
Q

What 3 vaccines are recommended for pregnant mares? What 5 are used to boost colostrum? What is risk-based?

A
  1. rabies - prior to breeding
  2. EVA - prior to breeding
  3. EHV - 5, 7, 9 months of gestation

tetanus, EEE, WEE, WNV, influenza - 4-6 weeks before predicted foaling

leptospirosis

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2
Q

What is the leading cause of infectious abortion in horses worldwide? How is it transmitted?

A

equine herpesvirus (EHV)

inhalation or ingestion of aborted tissues - infection persists in a latent state

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3
Q

What clinical sign is indicative of EHV in periparturient mares? What is the pathogenesis?

A

abortion between 5 months to term without any clinical signs of infection

  • replicates in respiratory epithelial cells
  • spreads to regional LNs and vascular endothelium of many organs
  • placental invasion causes autolysis
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4
Q

What 3 gross lesions are seen in cases of EHV abortion?

A
  1. fresh aborted fetus
  2. hepatic necrotic foci
  3. fibrotic plug in trachea
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5
Q

What vaccines are recommended for mares against EHV? What schedule is typically done? What efficacy do they have?

A

EHV-1 and EHV-4 (killed)

5th, 7th, 9th months –> immunity to vaccination is short-lived

does NOT offer 100% protection, but does reduce incidence of abortion

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6
Q

What are the 4 morphological types of equine placentitis?

A
  1. ascending - most common, infection from cervix
  2. nocardioform - focal, mucoid, uterine body and base of uterine horns
  3. diffuse - hematogenous
  4. multifocal - rare, fungal plaques
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7
Q

What pathogens cause each form of equine placentitis?

A
  1. ascending - Streptococcus equi subsp zooepidemicus, Klebsiella pneumonia, E. coli, Pseudomonas aeruginosa
  2. nocardioform - Crossiella equi, Amycolatopsis spp
  3. diffuse - Leptospira spp
  4. multifocal - Candida albicans, Aspergillus spp
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8
Q

How does ascending placentitis develop? What are the 2 most common etiologies?

A
  • pathogens migrate proximally through the cervix, starting at the cervical star region
  • when organisms enter the chorioallantois, they release pro-inflammatory cytokines and prostaglandins
  • this results in premature delivery –> red bag!
  1. failure of mucus plug
  2. weight of fetus and uterus - lack of cartilage allows cervix to stretch and open with increased weight
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9
Q

What are 4 signs of ascending placentitis?

A
  1. premature udder development*
  2. premature lactation*
  3. vulvar discarge
  4. abortion
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10
Q

What are the 2 most common causes of nocardioform placentitis? In what region is this most commonly seen?

A

Gram positive branching actinomycetes - Crossiella equi, Amycolatopsis spp

central KY - sporadic, hot and dry summer/fall

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11
Q

What is the most common result of nocardioform placentitis? What is the characteristic placental lesion?

A

late gestational abortion or delivery of premature stillborn or weak foals

copious mucoid exudate adherent to the surface of the chorion at the junction of the uterine body and base of gravid horn

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12
Q

What diagnostics are recommended for nocardioform placentitis? What is treatment like?

A

transabdominal U/S, culture following abortion

not very effective - difficult for antibiotics to reach this location and get past mucus

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13
Q

What are 3 parts of the routine examination in cases of suspected placentitis?

A
  1. transabdominal ultrasound - fetal viability
  2. vaginal exam - inspect cervix and look for discharge
  3. transrectal ultrasound - measure the combined thickness of uterus and placenta, assess placental separation
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14
Q

How is combined thickness of uterus and placenta calculated? What are the expected values at various points of gestation?

A

transrectal U/S - identify the middle uterine artery that runs parallel to the uterus and measure thickness of the uterus and chorioallantois just cranial to the cervix and calculate the average

  • 151-270d = <7 mm
  • 271-300d = <8 mm
  • 301-330d = <10 mm
  • 331d-term = <12 mm
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15
Q

What are 3 strategies of treating placentitis in mares?

A
  1. control infection - antimicrobials must be able to penetrate and accumulate in allantoic fluid (PPG + Gentamycin, TMS)
  2. reduce associated inflammation - Flunixin meglumine, Phenylbutazone, Firocoxib, Pentoxifylline (free-radical scavenger, promotes blood flow)
  3. promote uterine quiescence - Altrenogest
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16
Q

What predisposes to umbilical torsion? What typically results?

A

longer umbilicus - more room to twist (4-7 twists are normal)

vascular occlusion = fetal death and autolysis, typically at 6-8 months, when the fetus tends to have high mobility

17
Q

What are 3 signs of prepubic tendon rupture? When in gestation does this typically occur?

A
  1. ventral edema
  2. dropped abdomen
  3. bloody mammary secretions

late-term gestation - increased fetal weight, weakened muscles cannot support

18
Q

Where does uterine torsion in horses occur? What is the most common sign? When does this typically happen?

A

cranial to the cervix

colic

mid to late gestation

19
Q

What toxicity can affect fetal development in horses? How?

A

ergot alkaloids produced by endophyte-producing fescue have dopaminergic-like activity, which decreases prolactin and inhibits ACTH secretion –> no fetal stress to induce parturition

20
Q

What are 5 signs of fescue toxicosis in a pregnant mare? When is this most commonly seen?

A
  1. increased gestation length
  2. agalactia
  3. increased placental thickness
  4. oversized, dysmature foals
  5. abortion due to placental separation (red bag!)

last month of gestation

21
Q

What are 2 parts to treating fescue toxicosis?

A
  1. remove from fescue 30-45 days from foaling
  2. supplement with domperidone (DOPA antagonist) - increases prolactin from mammary glands
22
Q

What are 6 signs of impending parturition in mares? When are each seen? What is recommended before the due date?

A
  1. mammary gland development - 2-6 weeks
  2. perineal relaxation - 1-3 weeks
  3. teat engorgement - 7-10 days
  4. waxing of teats - colostrum leaks and dries, 48-72 hours
  5. elongation and swelling of vulva - 0-24 hours
  6. dripping milk from udder - 12-24 hours

remove vulvoplasty (Caslick) 1-2 weeks prior

23
Q

What are 3 ways of predicting time of parturition?

A
  1. calcium level - calcium carbonate > 250 ppm
  2. pH < 6.4
  3. Na+/K+ inversion - decreased Na, increased K

all measured in mammary secretions

24
Q

What are 2 options for monitoring timing of parturition?

A
  1. video camera
  2. vulvar device - Foalert senses water breaking
25
Q

What happens in the 3 stages of mare parturition?

A
  1. preparatory cervical softening, fetus rotates dorsopubic to dorsosacral, myometrial contractions, chorioallantois ruptures
  2. expulsion of foal
  3. expulsion of fetal membranes within 3 hours post foaling
26
Q

What is red bag?

A

emergency - premature placental separation results in no involution of placenta

  • fetus unable to break through, must be cut open
27
Q

What are 3 sequela of retained placenta?

A
  1. metritis
  2. laminitis
  3. endotoxemia
28
Q

What is the 1-2-3 rule of foaling?

A

HOUR 1 - foal stands

HOUR 2 - foal nurses

HOUR 3 - foal passes meconium and pare passes placenta

29
Q

How should the equine placenta be examined? What are the 2 surfaces?

A

laid out in an F or Y shape to identify all areas

  1. RED = chorionic surface (uterus side)
  2. BLUE = allantoic surface (fetal side)
30
Q

What is the cervical star? What if one of the two horns of the placenta are missing upon examination?

A

pale area of the placenta which apposes the cervix - site of ascending infection into the placenta

retained placenta

31
Q

What are some abnormalities that are looked for on examination of the placenta?

A
  • avillous areas
  • exudate - Nocardioform = purulent
  • abnormal placental weight - should be ~10-11% of foal weight, heavier = placentitis
32
Q

When does the first postpartum estrus occur in mares? Why is this possible? What is fertility like in this time?

A

7-9 days postpartum

less invasive placentation

controversial - ranges from normal fertility to 10-20% lower, may be better if delayed after histological involution (30 day heat after foal heat)

Theriogenology (22 decks)

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