Viral Causes of Reproductive Diseases in Equine. Reproductive diseases of equine. equine reproduction Horse viral diseases related to reproduction

1. Viral Causes of
Reproductive
Diseases in Equine
Dr. Muhammad Awais

2. Viral Causes of Reproductive Diseases
• Two important viral diseases of breeding horses
1. Equine herpes virus infection
2. Equine viral arteritis

3. Equine herpes virus infection
• Equine herpes virus 1, 3 and 4 causes reproductive problems
1. Equine herpes virus 1 & 4 (EHV1 & EHV4) causes Viral Abortion
2. Equine herpes virus (EHV3) causes Coital Exanthema

4. Viral Abortion
• Also called rhino-pneumonitis
• Caused by EHV1 & 4.
• EHV-1, causes abortion, respiratory signs, neurological signs
• EHV-4, usually causes respiratory disease only but can
occasionally cause abortion.
• Abortion – last trimester
• Infect multiple types of cells
• Lytic and latent cycle
• Latency – trigeminal ganglia and CD8+ cells

5. Transmission
• Horse - to – horse
• Ingestion and inhalation
• Aborted material, semen, aerosol droplet
• Reservoir – latently infected horses
• Stress, transport can reactivate latency
• Less persistent in environment
• Infection acquired in first weak of birth

7. Pathogenesis
Inhalation
Replicate in upper
resp. tract mucosa
In uterus – vasculitis
– abortion
Disseminated in all organs
including trigeminal ganglion,
CNS, uterus during viremia
Enter to lamina
propria, endothelial
cells, CD8+ cells
Brain – vasculitis,
thrombo-ischemia,
encephalopathy
Tiwari S.C, et al.,

8. Clinical signs
• Nasal discharge, conjunctivitis, lymphadenopathy, no cough
• Abortion – last trimester
• Neonatal infection – fatal
• Stallion – poor semen quality
• CNS – ataxia, paralysis, bladder dysfunction

9. Diagnosis
• There is no test to detect latent carriers
• Virus isolation
• PCR
• Serology

10. Multifocal hemorrhages,
rubbery lung
Multiple necrotic foci in liver
Hemorrhage and
necrosis of brain
stem
Aborted fetus,
enclosed in amnion

11. Lesions
Necrotic foci in liver
Eosinophilic inclusions in
hepatocyte
Vasculitis in CNSNuclear debris in splenic
follicle lymphocytolysis
EHV-1 particles nucleus. Organelles of the cytoplasm
degeneration hydropic dilation of sER,mitochondria,
detached ribosomes of rER

12. Control and prevention
• Keep weaned foals and yearling away from pregnant mares
• Aborted material and contaminated bedding should be burned
• Aborted mare should be isolated for at least 1 week with strict control admission to
box and routine hygienic measures
• Outside mares should not allowed onto infected premises until at least 1 month after
the last obrtion
• Vaccination two vaccines against EHV1 are available dead and attenuated
• Ideally all horses on premises should be vaccinated.

13. Coital Exanthema
• Caused by herpes virus (EHV3)
• Spread by coitus
• Vesicular Lesions on vulva , vestibule,and penis.
• These vesicles rupture and produce infected ulcers.
• Usually are healed with local antibiotic treatment.
• Coitus Cannot be performed by infected mare or stallion.
• Condition is resolved in 14 days.

14. Viral arteritis
• Caused by Equine arteritis virus belong to genus Arterivirus, family Togaviridae
• The virus which causes EVA was first isolated from horses in Ohio in 1953
• About 80% abortion during clinical disease
• Characterized by depression, edema of limbs, intense pink or red conjunctiva,
palpebral edema, enteritis, pneumonic complications and abortions

15. Transmission
• Via respiratory route or by ingestion
• Venereal transmission by stallions
• Tissues and fluids of aborted fetus contained large mass of virus
• Virus shed in the urine
Holyoak G.R., et al.,

17. Pathogenesis
Virus
Nasopharynx Lungs/
bronchial
lymph nodes
Blood
(viremia)
Body tissue/
fluids
Abortion in
mare
Shed in
semen

18. Lesions
• Congestion, petchiae in conjunctiva, resp tract and guttural pouches,
• Hydrothorex, petichae in pleura, heart, pericardium and lungs,
• Ascites
• Enlargement of LN
• Petichae on endocardium, epicardium, mesentery
• Small intestine, caecum and colon oedematous and congested

19. Microscopically
• Small arteries and necrosis and deposition of
eosinophilic mass in tunica media with cellular
infiltration in adventitia
• Platelet thrombi in lumen
• Abortion -necrotizing myometritis

20. Control and prevention
• Administration of a modified live and formalin-inactivated vaccine use in
non pregnant mares and in stallions.
• Vaccinated horses or any other horses with titers to EAV may not be
eligible for export to certain countries.