Equine Viral Respiratory Disease Flashcards
who is most affected by viral infections?
young and old
what are the risk factors for viral disease?
stocking density
lack of prior exposure
exercise?
how does intense exercise affect immunity?
oxidative stress
changes in catecholamine release
cytokine release and activity
decreased secretion of mucosal antibodies
decreased functional activity of blood and pulmonary leukocytes
what viruses cause respiratory disease in the USA?
equine influenza AE2
equine herpesvirus 1, 2, 4, 5
equine rhinitis virus
equine viral arteritis
adenovirus
hendra virus- exotic disease Australia
what type of virus is influenza?
orthomyxovirus: double stranded RNA
what is onset like of influenza?
sudden onset
incubation period 1-3 days
how can you diagnose equine influenza virus?
serology: slow
virus isolation: slow and false positives
ELISA: fast
PCR: fast- 36 hours
when should you sample for virus isolation?
early in disease
how can you treat equine influenza virus?
rest
good nursing care
NSAIDs
monitor clinical signs for secondary bacterial pneumonia and treat as needed
when should you think about a secondary bacterial infection with viral disease?
non-resolving fever
purulent nasal discharge
difficulty breathing
what is antigenic drift like?
big changes in chunks of RNA
can jump species
what are the two main variations of herpesviruses?
alpha
gamma
what can amplify and maintain virus reservoir of herpesvirus?
latent dam to foal
viral latency in foals/weanlings
periodic reactivation and shedding
what is the clinical presentation like of equine herpesvirus 1 and 4?
similar to every other respiratory virus
EHV-1 neurologic disease and abortion too
what are the gamma herpesviruses?
EHV-2
EHV-5
what is ERAV associated with?
anorexia, serous nasal discharge, laryngitis, bronchitis, coughing, lymphadenopathy
what does hendra virus have a tropism for?
vascular tissue
neurologic tissue
what type of virus is hendra virus?
henipah virus
what is the pathogenesis of viral diseases?
acquisition
colonization
replication
viremia
produce mucosal and humoral antibodies
stimulate cytotoxic T-lymphocyte and Th-1 responses
what exercise enhances immune function?
moderate
what conditions do horse transmit viruses better in?
dry, warm conditions
is influenza fragile or stable?
fragile- enveloped
what are the clinical signs of influenza?
sudden onset
incubation 1-3 days
high fever
deep dry cough
serous nasal discharge
myalgia
inappetence
enlarged submandibular lymph nodes
+/- edema of legs and scrotum
how should you sample for equine influenza?
nasopharyngeal>nasal
dacron/rayon not cotton
plastic or wire end not wood
do not use bacterial transport swabs
what in influenza makes horses more susceptible to infection?
epithelial necrosis
what is genetic drift?
minor change: same species, one virus, new strain
what are the alpha herpesviruses?
EHV-1
EHV-4
how can you treat equine herpesvirus?
rest
nursing care
NSAIDs
IFN-gamma? not proven
antivirals? expensive
what is EHV-5 associated with?
pulmonary fibrosis in adults
most young horses exposed
uncommon cause of disease
what are ERAV and ERBV classified as?
Apthovirus- with FMB
Erbovirus
how prevalent is ERAV?
endemic worldwide
so is ERBV
how is ERAV transmitted?
inhalation and urine
ERBV only inhalation
what is ERBV associated with?
serous nasal discharge
fever, anorexia
coughing
lymphadenitis
leg edema
lymphadenopathy
which horses have higher titers of equine rhinitis virus and IAD?
recent onset or exacerbation of equine asthma
how is hendra virus carried?
fruit bats
flying foxes
what is the mortality of hendra virus?
horses: 75%
humans: 57%
