Diseases of the Upper Respiratory Tract, Pt. 2 Flashcards
What is the major barrier to respiratory infection? What virus commonly targets this?
mucociliary clearance at the trachea transports mucus and dust toward the pharynx to be coughed out
EIV
What is the major way that viral upper respiratory infections are diagnosed?
nasopharyngeal or nasal swab PCRs
can get answers within days
What are the 4 major causes upper respiratory infections in horses?
- EHV-4
- EIV
- S. equi
- EHV-1
What are the similar clinical signs and treatments seen in viral respiratory infections?
CLINICAL SIGNS - fever, cough, mucopurulent nasal discharge, exercise intolerance
TREATMENT - rest, low dust, supportive care (ventilation, plenty hay/clean water)
When is it recommended to add NSAIDs to the treatment plan for viral upper respiratory infections? Which medication is used? How long should horses rest?
when horses develop fevers and become inappetent
Banamine - Flunixin Meglumine
- rest 1 week per day of fever
- 2 weeks after coughing ends
How are viral upper respiratory tract infections prevented?
- biosecurity: isolate new horses for 28-30 days, maintain/clean equipment, disinfection
- vaccination
What kind of virus is equine influenzavirus (EIV)? What are the 2 most common subtypes?
RNA virus
- H3N8 - Florida clade 1 and 2 are in vaccines
- H7N7 - hasn’t been documented lately
What horses are at highest risk of EIV infection? What also affects risk of infection?
- young/old
- naive/unvaccinated
- those undergoing stress associated with shipping and mingling
viral strain
In what 2 ways is EIV transmitted? What is its incubation like?
- direct - aerosols, breathing space
- indirect - equipment, humans, shared water buckets
1-3 days (quick!)
What 4 unique respiratory clinical signs are seen with EIV infection? What are some complications of infection?
- deep, dry cough that typically lingers
- serous to mucopurulent nasal discharge
- myalgia
- edema
secondary infections and myositis
Why arent viral isolation and serology typically recommended for diagnosing viral respiratory disease?
both can take 1-3 weeks, so they aren’t extremely helpful for quick diagnosis
What unique test is commonly used for EIV respiratory infection diagnosis?
ELISA —> ready within 30 mins to a day
How is the EIV vaccine classified? What types are available?
risk-based —> not a core
IM and IN
What are the differences between EHV-1 and EHV4? What else is unique about EHV-1?
- EHV-1 = respiratory, abortion, and neurologic syndromes
- EHV-4 = respiratory (abortion) syndrome
EHV-1 typically undergoes cell-associaetd viremia and can be translocated from the airways
What kind of virus is EHV? How does it act within hosts?
dsDNA
it is ubiquitous in the environment and 80-90% of horses are infected before the age of 2, where the virus typically lays dormant in trigeminal ganglia or T-lymphocytes
How is EHV transmitted? What is its incubation like?
- direct = aerosols
- indirect = fomites
- vertical = from mare to foal in utero
2-10 days
What are the 4 major target tissues of EHV?
- airway epithelium
- local LNs
- viremia
- vascular endothelium
What is the pathogenesis of EHV? What pattern is typically seen?
the virus causes focal epithelial erosion, which causes inflammation and vasculitis
infection —> latency —> reactivation —> transmission —> OUTBREAK
What are 4 unique clinical signs seen with EHV respiratory infection?
- late trimester abortions without impending signs (fetus will show not evidence of autolysis)
- weak foals unable to nurse (death)
- myeloencephalopathy
- pulmonary vasculotropic infection
How do reproductive signs with EHV-1 and EHV-4 infections differ?
EHV-1: abortion storms
EHV-4: less frequent abortions, more sporadic
What unique diagnostic technique can be used to diagnose EHV infection?
fluorescent Ab from NP swab or fetal tissue —> diagnosis within 24 hours
What 3 specimen can be collected for PCR diagnosis of EHV infection?
- NP swab - acute
- citrated of EDTA blood - can be latent in T-lymphocytes found in the buffy coat
- fetal tissue
What at risk horses are recommended to be vaccinated for EHV?
- < 5 y/o
- on breeding farms in contact with pregnant mares
- frequent movement on/off premises
- performance or show horses
What respiratory virus is considered reportable to the OIE? What kind of virus is it? What strain is most important?
equine arteritis virus
ssRNA
Bucyrus
In what 2 countries is EAV not found? How is it transmitted?
Japan and Iceland
- direct: aerosols
- indirect: fomites
- vertical: mare to foal in utero or venereal
What are the 4 target tissues of EAV? What is its incubation like?
- airway epithelium
- local LNs
- viremia
- vascular endothelium
3-14 days
Where can EAV persist? What is the pathogenesis like?
male accessory sex glands and respiratory organs
virus causes focal epithelial erosion, leading to inflammation, viremia, and pan vasculitis —> persistent infection
What 5 unique clinical signs are associated with respiratory EAV infection? What is seen in foals?
- conjunctivitis
- edema
- stiffness of gait
- rash
- abortion at 3-10 months where fetus is partially autolyzed
interstitial pneumonia and pneumoenteritis
What specimen can be used on PCRs to diagnose EAV infection?
- semen
- fetal tissue
- NP swab
What 3 viruses cause respiratory signs, but are extremely rare in the US?
- equine rhinitis virus A and B
- African horse sickness virus
- Hendra virus
How often should a horse participating in competitions be vaccinated against influenza and EHV-1?
a. every year
b. every 6 months
c. every 2 months
d. every 2 years
B
The vaccine against EHV-1 has questionable/no efficacy against which disease form?
a. respiratory
b. neonatal
c. neurologic
d. reproductive
C
EIV vs. EHV vs. EAV etiology, clinical signs, control:
EIV vs. EHV vs. EAV distribution, transmission, incubation, target, pathogenesis, persistence:
EIV vs. EHV vs. EAV tests/specimens/time for results:
