Equine Viral Respiratory Disease (first lecture done)

What are the main equine viral respiratory diseases?

Equine influenza and equine herpesvirus

Also adenovirus, equine viral arteritis, african horse sickness, hendra/nipah

What are the C/S of most equine viral respiratory diseases?

Fever, depression, anorexia, lymphadenopathy

Serous nasal discharge

Concerns for secondary bacterial infections

How do you treat equine viral diseases?

Rest, NSAIDs, TLC, antibiotics if secondary infection

What is the epi info with EIV?

Young horses get it with a brief incubation period spread via direct contact

High morbidity and low mortality

How often should you vaccinate for influenza?

Every 6 months

What pathological changes does equine influenza cause?

Loss of cilia and secondary bacterial colonization

What is the pathogenesis of equine influenza?

Attaches to respiratory epithelium via HA spikes

Cause destruction of respiratory epithelium

Secondary bacterial infection can occur mostly, Strep zoo

T/F Strep. zoo is a normal component of URT?

True, once damage is present it will colonize

How do you diagnose influenza?

qPCR from a nasal swab

Can do a virus isolation or ELISA sometimes

How do you prevent influenza with an inactivated vaccine?

IM vaccine that induces circulating IgG

Given every 6 mo in performance. annual in pasture

Foal series in first 3 years of life

Pregnant mares get colostral IG

How do you prevent influenza with a MLV?

Intranasal and temp sensitive

Causes local immune response for 12 months

Close to natural immunity

When is a MLV preferred for influenza?

In an outbreak due to rapid response

At risk foals <6 months old

What is a common myth in influenza vaccine for foals?

Early vaccination induces tolerance

Describe EHV 1 and 4

Alpha herpesvirus with ubiquitous equine viral pathogen

Large double stranded DNA virus

Viral encoded proteins

Related but separate

What does EHV 1 and 4 cause?

Respiratory disease (Rhinopneumonitis)

Abortion

Neonatal illness

What disease can ONLY EHV1 cause?

Neurologic disease EHM (equine herpes myelitis)

Why is EHV hard to control?

Latency and subclinical carriers as well as fomite transmission

What is the disease pathogenesis of EHV?

Infects respiratory epithelium and infects lymphocytes and monocytes that circulate and cause viremia

How is EHV transmitte?

Fluid from nasopharynx, repro tract, infected fetus

Aerosolized particles

Fomites from handlers onto horses

What causes recrudescence (reactivation)?

Stress from weaning, long-distance transport, concurrent illness

Iatrogenic from corticosteroids or cyclophosphamide

How do you treat herpesvirus patients?

NSAIDs, CCS, rest, TLC, antibiotics if needed and immunostimulants

How do you diagnose EHV?

PCR from tissues or blood

Virus isolation from nasal swab, buffy coat, tissues

Serology

How do you vaccinate for EHV1/4?

Inactivated vaccine is safe with reactions at site of injection and CAN be given to pregnant mares

Modified live for mucosal protection. CTL activation is important. NOT indicated for pregnant mares

What is antigenic shift?

Sudden change in HA due to recombination with another influenza

What is antigenic drift?

Random mutation in HA and NA

Limits vaccine efficacy

How do you clinically manage EIV?

Rest from exercise

NSAIDs

Good supportive care and protection from harsh weather

Antibiotics if secondary infections occur

Describe the canarypox vectored vaccine for EIV?

2 doses with DIVA compatibility

Give to at risk foals <6 months or pregnant mares 4 weeks before foaling

What are the alpha herpesviruses?

1,3,4

What are the gamma herpesviruses?

2 and 5

What are C/S of EHV?

Fever, depression, anorexia, lymphadenopathy

Nasal discharge that is serous to mucoid

Rarely coughing

What is the vaccine protocol for rhinopneumonitis EHV-1/4?

Inactivated IM vaccine given every 6 months to active horses

Series of 3 in first year for foals/weanlings starting at 3-4 months old

MUST BE MULTIVALENT WITH BOTH STRAINS

What is the main use for the high antigen load vaccine of EHV-1?

Give to pregnant mares every 2 months of pregnancy starting at 5 months to prevent abortion storms

This will make the mare very sore at injection site

What is the problem with the MLV for EHV-1?

Does not protect against neurologic herpes

When does EHV-1 cause abortion?

Late in gestation with the mare appearing healthy

Fetus is basically destroyed by the virus

What does neonatal EHV-1 look like?

Very sick with poor prognosis from a mare that was not vaccinated

What are the C/S of neurologic EHV?

Xanthochromia, ataxia, paresis, incontinence

What does EHV-2 cause?

Cytomegalovirus and immune suppression

What does EHV-3 cause?

Coital exanthema