Equine Abortion - Infectious Causes Flashcards
Pregnancy wastage
Embryonic loss
- fertilization - 40 days of gestation
- after pregnancy confirmation
- abortion: 40-300 days
- premature loss/stillbirth: 300-320 days
Abortion
Termination of pregnancy before fetus is capable of extra-uterine life
- infectious/non-infectious
- in only 60% of cases is a causative agent ID’d
- overall rate is 5-15%
Most abortions are the result of placental dysfunction
- placentitis
- twinning
Clinical signs
- premature mammary development (twins)
- vulvar discharge
- absence of any sign is common
Signs of placentitis/impending abortion
- absence of any sign is common
- premature udder development
- scant vaginal discharge
- uterine thickening observed on US
What to do in abortion cases
- complete history, recent travel
- submit aborted fetus and placenta
- uterine culture
- isolation of mare until diagnosis
Big rule outs for EQ abortion
- equine rhinopneumonitis
- ascending placentitis
- nocardioform placentitis
- leptospirosis
- equine viral arteritis (reportable)
EHV-1
- respiratory disease
- neurological disease
- abortion
EHV-4
Primarily respiratory
EHV transmission
- inhalation
- direct contact
- latent carriers
Equine rhinopneumonitis
EHV-1
- most important cause!
- transmitted via direct contact thru nasal secretions
- latent carriers
- abortion generally occurs after 5 months gestation without maternal signs
Equine rhinopnemonitis causes ______
Late term abortions
- foal is normal appearing
- fetal lesions: SQ edema, jaundice, enlarged liver with white spots
- no premonitory signs
Rhinopneumonitis diagnosis
Histopath, liver lesions, VI, FAT, or PCR
- vaccinate preg mares at 5, 7, 9 mos post gestation
- isolate young stock
- maintain closed herd
- avoid contact w/ horses from shows
Bacterial placentitis
Most common cause of equine abortion!!
- also causes premature delivery and neonatal death
- ascending infection, except w/ lepto and nocardioform
Ascending placentitis
- udder development
- increased uteroplacental thickness
- vaginal discharge
- compromise of placental function w/ separation of placenta
- fetal death and expulsion ensue
- edematous and thickened chorioallantois
- fibrinous exudate at cervical star region
Ascending placentitis occurs in _______
Older multiparous mares
- poor perineal conformation
- cervical incompetence
- strep equi sp. zoo (most common)
- e coli
- klebsiella pneumoniae
- pseudomonas aeruginosa
- aspergillus
Ultrasonography
- combined thickness of uterus and placenta
- cranial to cervix
- distance between middle branch of uterine artery and allantoic fluid
- placental separation
- purulent material
CTUP _____ with increasing days of gestation
Increases
Goals of ascending placentitis treatment
Maintain pregnancy long enough to allow fetal maturation (precocious maturation)
- antibiotics
- anti-inflammatory
- tocolytic to prevent uterine contraction
Equine mycotic placentitis
- ascending
- thickened chorioallantois
- fetus is fresh with growth retardation
- dermatitis
- fungal hyphe seen in placenta, liver, lungs, stomach
- aspergillus, mucor, candida, histoplasma
Nocardioform placentitis
Actinomycetes
- thickening at base of uterine horns
- late gestation (abortion, stillbirths, weak foals)
- placental lesions (thick, brown exudate)
CTUP with nocardioform placentitis will be ______
Normal
Nocardioform is common in ______
Central KY
Equine viral arteritis
Equine viral arteritis virus
- subclinical infections common
- clinical: fever, conjunctivitis, nasal discharge, abortion, edema (ventrum, limb, eyelid)
EVA seropositive status
- standardbred: 85%
- american saddlebred: 25%
- quarter horse: 12%
- thoroughbred: 2%
EVA transmission
- aerosol
- venereal
- contact with bodily fluids
- vertical
- fomites
EVA pathogenesis
- vascular endothelial cells
- myometrial necrosis
EVA abortion
3-8 weeks after initial infection
- no premonitory signs
- partially autolyzed
EVA diagnosis
IHC tissue samples
- viral isolation via nasopharyngeal swabs, look at buffy coat
EVA in carrier stallions
1/3 of stallions
- testosterone dependent (geldings are not carriers)
- virus neutralization assay –> tests for exposure, then do viral isolation
EVA vaccination will cause ______
Seropositive status!
Management of carrier stallions
- state vet
- isolated from other stallions
- vaccinated mares
- seropositive mares
Mare breeding to carrier stallions
- serologic status
- vaccinate and isolate seronegative mares
- seropositive mares isolated 24-48 hrs post breeding
Are mares chronic carriers?
No!
Prevention of carrier state
- determine serologic status
- vaccinate 6-12 months of age –> determine and document serologic state before vaccination
Leptospirosis
Sporadic cause of equine abortions/placentitis
- generally occurs 6-9 mos gestation
- L. interrogans serovar Pomona type kennewicki is most common in NA
- diffuse lesions due to hematogenous spread
Placentitis not involving cervical star
- thick, heavy, edematous, hemorrhagic placenta
- brown edema of the chorion
- funisitis
Lepto fetus
Icterus, liver enlargement, nephritis, hepatitis
- dx with MAT on serum of mares and aborted fetuses
- fluorescent antibody test on mare’s urien, fetal liver/kidney, placenta
- isolate aborting mares because shedding can last up to 14 weeks
- wildlife are carriers
Lepto treatment
- isolate affected mares
- titer exposed to mares
- antibiotics
- prevention: limit exposure standing water, vaccination
Dourine
Venereal transmission of Trypanosoma equiperdum (protozoal parasite)
- low morbidity, high mortality
- spread via male to female
- middle east, north and south africa, central and south america
- not present in US
Dourine symptoms
Chronic disease
- edema of penis, prepuce and scrotum
- edema of external genitalia, raised plaques and discharge in mares
- test, slaughter and quarantine used for control
Piroplasmosis
Babesia caballi, Thelaria equi
- mares have icterus and hemoglobinuria
- excessive fluid in peritoneal/thoracic cavity
- cELISA by USDA lab
- recently in FL, MO, KS, TX
- reportable!!!
