Equine Abortions

Question 1

abortion in mares

Answer 1

• expulsion of the non-viable fetus and its membranes between 50 and 300 days of gestation

Question 2

main causes of equine abortions

Answer 2

• twin pregnancies
• umbilical cord torsion (UK- #1 cause)
• viral, bacterial or fungal infections
• digestion of a large amount of eastern tent caterpillars

Question 3

twin pregnancies in mares

Answer 3

• insufficient placenta for twins
• usually late abortions

Question 4

umbilical cord torsion

Answer 4

• etiology
  
  • excessively long umbilical cord (>85cm at term)
• more than 5 twists
• blood flow restriction
• fetal death and/or abortion

Question 5

viral abortions

Answer 5

• Equine rhinopneumonitis“Rhino”
  
  • Equine Herpesvirus 1
  • reportable disease
• Equine Viral Arteritis
  
  • reportable disease

Question 6

Equine Herpesvirus 1

Answer 6

• repiratory disease, neurological disease, abortion
• transmission
  
  • respiratory, contact with infected tissue, fetuses, placenta, fluids
• virus viable for several weeks in the environment
• endemic to USA

Question 7

clinical signs of EHV 1

Answer 7

• no clinical signs until abortion
• late abortions: 7+ months of gestation
• abortion of fresh fetus
• possible “abortion storms” in not vaccinated horses

Question 8

diagnosis of equine abortions caused by EHV 1

Answer 8

• aborted fetus and fetal membranes
  
  • necropsy: necrotic foci of the liver and edematous lungs
  • histopathology: eosinophilic inclusion bodies
  • virus isolation
  • PCR

Question 9

treatent and prevention of EHV 1

Answer 9

• no specific tx
• supportive tx, if needed
  
  • most infected foals die shortly after birth
• prevention
  
  • separating pregnant mares from younger animals
  • vaccinations during months 5, 7, and 9 of pregnancy (3 vax)

Question 10

Equine Viral Arteritis

Answer 10

• contagious viral disease of equids which can cause abortions in mares and carrier status in stallions
• global distribution
• recent outbreaks in New Mexico, Utah, Idaho
• causative agent:
  
  • equine arteritis virus (EAV), genus Arteriviridae, order Nidovirales

Question 11

transmission or EVA

Answer 11

• respiratory or venereal
• stallions: carriers
• virus survives in frozen semen

Question 12

clinical signs of EVA

Answer 12

• classic:
  
  • fever
  • lacrimation
  • nasal discharge
  • edema of legs, ventral abdomen, and/or scrotum

Question 13

reproductive consequences of EVA infection

Answer 13

• not-pregnant mares bred by infected stallions do not lose pregnancy
• late pregnant mares infected by infected animals (respiratory route) often abort
• abortion storms occur in susceptible mares- up to 50-60%
• aborted fetus is partially autolyzed
• foals infected in utero may develop pneumonia

Question 14

dx of EVA

Answer 14

• only through approved lab
  
  • serum neutralization test
  • virus isolation from semen, placenta, fetal tissue, blood
  • PCR
  • test breed stallions*
  • if vaccinated, blood can test positive

Question 15

prevention of EVA

Answer 15

• test all breeding stallions once a year
• approved vax
  
  • determine and document serological status of the animal before vax
  • inform state vet before using vax
  • keep detailed records of vax

Question 16

bacterial infections

Answer 16

• bacterial placentitis
  
  • ascending
  • hematogenous
  • nocardioform
• leptosporosis
• abortions caused by endotoxemia

Question 17

bacterial placentitis

Answer 17

• most common causes of equin abortion in US***
• ascending:
  
  • Streptococcus equi zooepidemicus,
  • E. coli, K. pneumoniae, and P. aeruginosa
• nocardioform placentitis:
  
  • Nocardioform actinomycetes
• Hematogneous (rare):
  
  • Leptospira spp
• characteristic lesions on chorioallantois

Question 18

clinical signs of bacterial placentitis

Answer 18

• vaginal discharge
• premature mammary gland development
• abortion without warning signs

Question 19

dx of bacterial placentitis

Answer 19

• trans-rectal u/s: ascending placentits
• trans-abdominal u/s: Nocardioform
• avillous areas

Question 20

tx of bacterial placentitis

Answer 20

• systemic abx (TMS, penicillin, gentamycin)
• altrenogest (regumate)
• NSAIDs
• Pentoxifylline
• long term tx throughout pregnancy

Question 21

Take home messages

Answer 21

• equine abortions are devastation for a horse breeder
• vaccinating pregnant mares lowers their changes to abort due to EHV-1 infections
• early detection of ascending placentitis in mares allows successful trx resulting in a live foal

Question 22

infertility in mares

Answer 22

• non infectious causes
  
  • ovarian tumors
  • anovulatory follicles
  • developmental abnormalities
  • abnormalities of the external genitalia

Question 23

ovarian tumors

Answer 23

• Granulosa-Theca Cell Tumor (GTCT or GCT)
• cystadenoma
• dysgerminoma
• teratoma (very rare)

Question 24

Granulosa-Theca Cell Tumor

Answer 24

• most common
• hormonally active
• benign
• unilateral enlargement of one ovary
• opposite ovary
  
  • small, inactive

Question 25

clinical signs of GCT

Answer 25

• behavioral changes
  
  • stallion-like responses
  • aggression
  • anestrus
  • persistent estrus-nymphomania

Question 26

dx of GCT

Answer 26

• transrectal palpation
  
  • enlarged ovary
  • lack of ovulation fossa
• u/s
  
  • multi-cystic
  • solid (very rare)
• GCT diagnositc panel
  
  • elevated inhibin (tell tale sign)
  • elevated testosterone
  • baseline progesterone
• new endocrine test
  
  • elevated AMH

Question 27

tx of GCT

Answer 27

• surgery
  
  • remove abnormal overy
  • should start cycling

Question 28

anovulatory/hemorrhagic follicles

Answer 28

• may be confused with GCT!
• ovulation fossa-palpable
• will spontaneously regress

Question 29

contagious equine metritis

Answer 29

• highly contagious bacterial venereal reportable disease of horses caused by Taylorella equigenitalis, a gram negative coccobacillus
• very strict regulations for import

Question 30

transmission of CEM

Answer 30

• venereal route
• contact with contaminated objects
• semen collection
  
  • doesn’t survive in frozen semen

Question 31

clinical signs of CEM in mares

Answer 31

• Mares
  
  • intense neutrophilic endometritis/metritis
    
    • grayish-white discharge
  • short-term infertility-few weeks
  • abortions- rare
  • mares and delivered live foals may become carriers
• Stallions
  
  • no clinical signs
  • local contamination on external genitalia
  • carrier state

Question 32

dx of CEM

Answer 32

• swabs for culture
• mares
  
  • clitoral fossa, clitoral sinus, endometrium
  • must culture all 3 sites on 3 sepearate days over 7 day period
• stallions
  
  • fossa glandis, urethral sinus, urethra, prepuce, penile body
  • cultures may be false negatives
    
    • breed to two test mares

Question 33

tx of CEM

Answer 33

• only under supervision of state vet
• 4% chlorhexidine and 0.2% nitroflurazone
• quarantine for 21 days and negative serology

Question 34

CEM summary

Answer 34

• highly transmissible, reportable dz
• high rate of infertility (40%)
• asympotomatic carrier status in stallions
• difficult to diagnose
• one of the internationally most controlled diseases in equine industry