Lecture 35: Diseases of the Upper Respiratory Tract 2

similarities of respiratory diseases

• clinical signs → fever, cough and nasal discharge, exercise intolerance

• treatment → rest, low dust, supportive care

• diagnosis → nasopharyngeal swab, nasal swab

similarities in treatment of respiratory diseases

• management → clean well-ventilated stall, plenty of hay and clean water

• NSAIDs → banamine

• rest → 1 week/day of fever; 2 weeks after end of coughing

prevention of respiratory diseases

biosecurity and vaccination

what is the USEF rule for EIV and EHV vaccination?

required vaccination/6 months

equine influenza virus (EIV)

• RNA virus

• antigenic drift

• H3N8 (A/equine/2)

• young and old horses; naive or unvaccinated

• stress/shipping/mingling

• transmission → direct or indirect

• incubation 1-3 days

clinical signs of EIV

• naive horses → rapid spread, severe clinical signs

• immune horses → attenuated severity

• fever, dry deep cough

• serous to muco-purulent nasal discharge

• inappetence, enlarged LN, myalgia

equine herpes virus etiology

• ubiquitous

• 80-90% of horses infected before age 2

• 80% latent infection

• herpesviridae, double stranded DNA virus

equine herpes virus epidemiology

• worldwide distribution

• transmission from aerosol, fomites, vertical

• incubation 2-10 days

• latency → trigeminal ganglia, T-lymphocytes

• pattern → infection, latency, reactivation, transmission

clinical signs of EHV

• mild MP nasal discharge

• transient pyrexia

• submandibular LN adenopathy

• inappetence, lethargy, edema, epiphora

• abortions → fetus with no evidence of autolysis

• EHV1 → abortion storms

• weak foals, unable to nurse; death

• myeloencephalopathy

• pulmonary vasculotropic infection

treatment and prevention of EHV

• supportive care

• biosecurity

• vaccination → adult, non-breeding every 6 months

• at risk → on breeding farms or in contact with pregnant mares, performance or show horses

equine arteritis virus

• reportable

• family arteriviridae, single stranded RNA virus

• 1 strain → bucyrus strain

equine arteritis virus epidemiology

• worldwide distribution

• transmission → aerosol, fomites, vertical, venereal

• incubation 3-14 days

• persistence in male accessory sex glands

• respiratory and repro organs

clinical signs of equine arteritis virus

• most infections are subclinical

• fever, depression, anorexia

• resembles other URTD

• conjunctivitis, edema, stiffness or gait, rash, foals with interstitial pneumonia

• abortion

which horse disease is exotic?

african horse sickness and hendra virus

how often should a horse participating in competitions be vaccinated against influenza and EHV1?

every 6 months

the vaccine against EHV1 has questionable efficacy against which disease form?

neurologic