Smith 5 - Equine Resp Flashcards
DDX for pleural effusion
bacterial pneumonia (73%)
-less common: hemothorax, chest penetration, esophageal perf, neoplasia, fungal pneumonia
frequent anaerobe in equine pleuropneumonia resistant to penicillins
bacteriodes fragilis
CS of rhodococcus
-chronic suppurative bronchopneumonia with extensive abscessation
Cough, fever, lethargy
__% of foals with subclinical rhodococcus recover without abx
80-90%
intestinal r. equi
multifocal ulcerative enterocolitis and typhlitis over the Peyer’s patches with granulomatous or suppurative inflammation of mesenteric / colonic LNs
-can be a single large mesenteric LN abscess adhered to bowel
r. equi polysynovitis tx
not necessary - if lung dz is responding to tx
r. equi septic arthritis
aggressive local tx needed
will be very lame
r. equi VapA gene
-only VAP to have a role in virulence
-encodes an immunodominant temperature-inducible surface-expressed lipoprotein
factors necessary for r. equi virulence
VapA gene
regulator genes virR and virS
type I immune response to r. equi
T helper lymphocytes produce IFN-g
sufficient to effect pulmonary clearance
type II immune response to r. equi
IL-4 production
not effective at clearing infection
common bacteria causing neonatal foal pneumonia <30 days
-sepsis / ascending infection
-E. coli, kleb, actinobacillus, salmonella
causes of pneumonia in foals 1-6 months old
strep zoo and r. equi
-less common actinobacillus, b. bronchiseptica, E. coli, kleb, pasturella, pseudomonas, salmonella
pneumocystis carinii
fungal cause of pneumonia, usually concurrent infection or in SCID foals
CS of URT fungal infection
serosanguineous or mucopurulent discharge and airway noise
BAL cytology w/ fungal pneumonia
degenerate neutrophils, intracellular hyphae
polyene antibiotic that combines with ergosterol in fungal cell membrane –> increased cell permeability
amphotericin B
destroy fungi by inhibition of ergosterol biosynthesis in the fungal cell membrane
-azoles
saprophytic fungus that causes granulomatous lesions in nasal passages, trachea, or soft palate
-histo similar to pythiosis
-hyphae are thin walled, highly septate, irregularly branching
conidiobolomycosis
saprophytic, round, basidiomycetous yeastlike fungus
-large heteropolysaccharide capsule that does not stain-
-causes pneumonia, rhinitis, meningitis, and abortion
cryptococcus neoformans
broad septet hyphae with parallel sides and acute right-angled branching
-vascular invasion
-pneumonia in immunocompromised horses, esp. ones with enterocolitis
aspergilliosis
prognosis of aspergillus pneumonia
FATAL
dimorphic saprophytic fungus; yeasts can be seen inside giant multinucleated cells
-spherical yeasts, unilateral broad based budding
-causes pyogranulomatous pneumonia, pulmonary abscesses, peritonitis, abscesses
blastomycosis
epizootic lymphangitis
histoplasmosis capsulatum
-ocular, cutaneous, respiratory, or asymptomatic dz
DDX: glanders
Field test: histofarcin skin test
soil saprophyte that likes semi-arid areas with sandy alkaline soil
-forms nonbonding spherules when inhaled
-causes weight loss, fever, abdominal pain, respiratory dz, nasal granulomas, and diffuse infections
coccidioides immitis
where does s. equi attach
cells in the crypt of the lingual and palatine tonsils, and to the follicular associated epithelium of the pharyngeal and tubal tonsils
strangles serology is useful for detecting
recent but not current infection
purpura hemorrhagic is a
-type III hypersensitivity
-aseptic necrotizing vasculitis
uncontrolled pulmonary inflammation and coagulation lead to accumulation and activation of leukocytes and platelets in the lungs, altered permeability of the pulmonary barrier, and accumulation of edema within the airways
ARDS
Severe ARDS
PaO2/FiO2 <100mmhg
Moderate ARDS
PaO2/FiO2 100-200 mmghg
-or PaO2 <42 on room air
Mild ARDS / ALI
PaO2/FiO2 200-300mmhg
-or PaO2 <63 on room air
perilla mint, crofton weed, crotalatia, and senecio all cause?
interstitial pneumonia in horses
Hx: weight loss, fever, cough
Rads: multiple coalescing nodular densities over a diffuse interstitial pattern
EMPF
__ can cause ARDS in older foals
rhodococcus
equine parasitic pneumonia
young foals, migration of parascaris equorum larvae through lung parenchyma
what toxic plants can cause interstitial pneumonia
PA’s (mostly crotalaria, trichodesma, and senecio) -toxic metabolite activated in the liver, travels to the lungs
crofton weed
perilla ketones
smoke inhalation pneumonia
acute diffuse interstitial, followed by opportunistic bacteria
4 phases of interstitial pneumonia
1) parenchymal injury and alveolitis
2) proliferative
3) chronic interstitial fibrosis
4) irreparable fibrosis
complications of interstitial pneumonia and fibrosis
-cor pulmonale
-pulmonary hypertension
definitive test for chronic interstitial pneumonia
lung biopsy + histo
culture medium for equine influenza
embryonated chicken eggs
anti-viral used for EMPF
acyclovir
most frequently diagnosed viral resp dx of the horse
influenza
the flu virus in horses
-enveloped, with segmented single stranded negative sense RNA
-Orthomyxoviridae
-members of group A
viral hemagglutinin (HA)
-glycoprotein
-determines host specificity
-receptor binding protein
viral neuraminidase (NA)
facilitates mobility of virus by assisting in the release of budding particles from host cells
influenza subtypes in horses
H7N7 (A/equine/1)
H3N8 (A/equine/2)
most significant influenza lesions are in the
lower airway
how does flu enter the resp epithelial cell
receptor mediated endocytosis
CS of influenza
-fever 48-96 hours post infection
-serous nasal discharge becoming more mucop
-dry hacking cough may last 3 weeks
-anorexia
EHV-1, 3, & 4 are
alphaherpesvirinae
-linear dsDNA
which EHV can infect other species (donkeys, cattle, camelids)
EHV-1
EHV-2 & 5 are
gammaherpesvirinae
equine coital exanthema
EHV-3
EHV-? can cause resp disease but only single abortions (not storms)
4
how does EHV-1 spread from resp tract
lymphocyte-associated viremia
-then spreads from leukocytes to epithelial cells at secondary site
development of EHM is correlated with
magnitude and duration of viremia
EHV-1 abortion
-last 4 months of gest
-vasculitis of small arteriolar branches of glandular endometrium
-thrombosis, microcotyledonary infarction, perivascular cuffing, and transplacental spread of virus
-spits out fetus with no warning signs
EHM effects
-widespread vascular injury
-damage to BBB
-thromboischemic necrosis in SC and brain
eq adenoviruses
-EAdV1 = acute resp dz, conjunctivitis, and fatal pneumonia in SCID arab foals
-EAdV2 = intestinal infection and d+ in normal foals
dictyocaulus arnfeldi infectious stage
L3 on pasture - ingested, migrate to intestines and lungs via lymphatics, infiltrate alveoli
what fungus helps spread lungworm
philbolus
IL-17
-implicated in asthma
-secreted by Th-17 cells
-promotes maturation, chemotaxis, and activation of neutrophils
-upregulated IL-8 expression and promotes airway neutrophilia
Glanders
-burkholderia mallei
-facultative intracellular gram negative bacteria
-nasal, pulmonary, or cutaneous forms
-nodules
-purulent yellow discharge
cause of EIPH
-pulmonary blood
-rupture of alveolar capillary membranes
-secondary to increase in transmural pressure
most reported primary lung tumor in horses
granular cell tumor
eupatorium adenophora
crouton weed poisoning
-pneumotoxicosis
in horses, is inspiration or expiration active?
both
when does cyanosis become apparent?
a. 5 mg/100 mL (5 g/dL) of deoxygenated hemoglobin is present
b. PaO2 is 35-45 mm Hg
c. Severely anemic patients may never become cyanotic
Pulmonary aspergillosis most often follows
severe gastrointestinal disease that resulted in mucosal compromise
most frequently diagnosed viral resp dz in the horse
FLU
H3N8 A/Eq/2
Dictyocaulus arnfieldi
direct life cycle
infective stage is L3
PPP 2-4 months
EVA replicates where
adrenals, thyroid, liver, testes, endothelial cell
EVA resp dz
Respiratory disease – periocular edema
Fever, anorexia, lethargy, serous oculonasal discharge, cough, conjunctivitis, distal limb, prepucial, scrotum, and mammary edema, and urticaria localized to the sides of the neck and face +/- generalize
Hendra Virus
Fever, respiratory signs, facial swelling, ataxia, head pressing, recumbency, frothy nasal discharge, tachycardia, death within 36 hours
Necropsy: syncytial giant cells containing cytoplasmic inclusion bodies with paramyxovirus nucleocapsid in the pulmonary endothelium
Dx of carbon monoxide toxicity
carboxyhemoglobin >10%
Diagnosing RAO
BAL neutrophilia
SAA
Haptoglobin
IAD is more common in horses that also have
DDSP
Gold standard Dx for Glanders
culture
primary pulmonary neoplasms
most frequently granular cell tumors
confined to the lungs
most common equine thoracic neoplasm
lymphosarc
gastric SCC also likes to met there
guttural pouch structures
cranial nerves VII, IX, X, XI, and XII, the cranial sympathetic trunk the internal carotid artery; and branches of the external carotid arter
