Post-Neonatal and Weanling Respiratory Diseases Flashcards
what parasite can cause lower respiratory disease in older foals and weanlings?
Parascaris equorum
should you use antibiotics in foals with respiratory disease?
yes: more fragile than adults
non-infectious causes of cough are unusual in foals
do horses with disease often have a normal CBC?
yes- all ages
for what can nebulizing with gentamycin or amikacin be useful?
Bordatella spp
what is Rhodococcus equi?
obligate aerobe
intracellular
gram positive, acid fast
pleomorphic cocco-bacillus
when do you see disease due to Rhodococcus equi in foals?
1-4 months old
where does Rhodococcus equi survive and replicate?
macrophages: inhibits phagosome/lysosome fusion
what are the five mechanisms of hypoxemia?
V/Q mismatch
diffusion impairment
shunt
hypoventilation
low FiO2
how long is the environment contaminated with Parascaris equorum?
up to 5 years
who is at risk for Parascaris equorum?
young or very naive or debilitated adults
most severe on breeding farms
what does Parascaris equorum have significant resistance to?
ivermectin
what are the bacterial causes of lower respiratory disease in older foals and weanlings?
opportunistic: Streptococcus equi subsp zooepidemicus
Rhodococcus equi
how common is cough with foal respiratory disease?
infrequent even with severe disease
what do Bordatella species produce?
beta-lactamase
what is opportunistic bacterial bronchitis and pneumonia known as?
snotty nose syndrome
undifferentiated distal respiratory tract infection
what are the risk factors for lower respiratory disease in foals?
high stocking density
dusty housing
nadir of immunosuppression: when maternal antibodies lapse
what is the epidemiology of Rhodococcus equi?
soil-borne- inhaled
10-20% farms endemic
likes warmth
only 100 organisms needed for infection
what are the common signs of Rhodococcus equi?
young foals, insidious infection
fever, dyspnea, crackles, wheezes, coughing
neutrophilia, lethargy
maybe normal on auscultation
how can you screen for Rhodococcus equi?
ultrasound screen
temperatures bi-weekly from 30-90 days of age
CBC with fibrinogen in a few
serum amyloid A
what causes of hypoxemia cause a large A-a gradient?
V/Q mismatch
diffusion impairment
shunt
what drugs can you use for Rhodococcus equi (intracellular)?
rifampin
macrolide: clarithromycin, azithromycin, erythromycin
why should you use macrolides with caution?
can cause severe diarrhea and hyperthermia in foals and mares
what is the life cycle of Parascaris equorum?
direct
migration
do horses usually self-cure of Parascaris equorum?
yes- 18 months
what organs does Parascaris equorum affect?
liver damage usually subclinical
lungs: inflammation, edema and consolidation
gut: mechanical obstruction and inflammation
how long may infections with P. equorum be patent?
3 months
what are the clinical signs of P. equorum?
coughing and mucopurulent nasal discharge
seldom febrile unless secondary infection
poor doers
ileus, impactions, rupture
why should you treat adults for P. equorum?
may harbor enough to be infective source
