Lecture 13 10/21/24 Flashcards
What are the predisposing factors for bacterial pneumonia?
-viral resp. diseases
-athletic events
-recent long trailer rides
-immunologic compromise
-anesthesia
-pharyngeal/laryngeal dysfunction
-esophageal obstruction
-EIPH
When does bacterial pneumonia occur?
-when bacteria are aspirated
-when bacterial infection is secondary to viral disease
Which gram-pos. species are associated with bacterial pneumonia?
-Strep. zooepidemicus
-Strep. pneumoniae
-Staph. aureus
Which gram-neg. species are associated with bacterial pneumonia?
E. coli
-Klebsiella pneumoniae
-Pasteurella spp.
-Actinobacillus spp.
Which anaerobes are associated with bacterial pneumonia?
-Clostridium
-Fusobacterium
-Bacteroides fragilis
What are the clinical signs of bacterial pneumonia?
-fever
-depression
-anorexia
-exercise intolerance
-tracheal sounds
-coughing
-nasal discharge
-resp distress
-weight loss
What sounds can be heard on auscultation in bacterial pneumonia patients?
-crackles/alveoli snapping open
-wheezes/air passing over fluid
-absence of breath sounds
What clinical pathology data is associated with bacterial pneumonia?
-hyperfibrinogenemia
-neutrophilia +/- left shift
-neutropenia in gram-neg infections
-hyperglobulinemia
What changes on blood gas are seen with bacterial pneumonia?
-low pH/acidosis
-low pO2/hypoxia
-increased pCO2/resp. acidosis
-potentially increased pHCO3/metabolic alkalosis (compensatory)
Which procedures are used to diagnose bacterial pneumonia?
-endoscopic examination
-transtracheal wash/bronchoalveolar lavage
-cytology and culture
What changes can be seen on radiographs with bacterial pneumonia?
-increased bronchial and/or interstitial patterns
-air bronchograms
What findings on ultrasound can be indicative of bacterial pneumonia?
-comet tails
-abscesses
-consolidation
-hepatisation
-pleural fluid
What are the types of treatment for bacterial pneumonia?
-primary: directed at causative agent
-secondary: directed at response to causative agent
-supportive: directed at total patient
What is the primary treatment for bacterial pneumonia?
-antimicrobial therapy
-based on culture/sensitivity, knowledge of common organisms, or trial and error
What must be considered when using antibiotics for bacterial pneumonia treatment?
-dose, duration, interval, and route
-continue treatment until symptoms attenuate for 7-10 days
-understand common microbial agents
-broad vs narrow spectrum
-adverse side effects of the drugs
-frequently monitoring clinical signs
Which antibiotics are first choice for bacterial pneumonia and used in a hospital setting?
-aminoglycosides
-beta-lactams
-cephalosporins
Which antibiotics are second choice for bacterial pneumonia and used for at home therapy?
-tetracyclines
-potentiated sulfonamides
Which antibiotics are the “big guns” for bacterial pneumonia treatment?
-fluoroquinolones
-macrolides
-chloramphenicol
Which antibiotic is used for anaerobic bacterial pneumonia?
metronidazole
When should antibiotic therapy be changed?
-temp. spikes after 24-48 hours
-no improvement in clinical signs
-adverse side effects occur
-lab support indicates resistance
What are the goals of secondary treatment for bacterial pneumonia?
-reduce/eliminate airway obstruction
-reduce/eliminate undesirable inflammatory reaction
-improve alveolar-vascular oxygen exchange
-provide immune enhancement
What are the components of secondary treatment for bacterial pneumonia?
-mucolysis and expectoration
-bronchodilation
-copage/breaking up mucus
-anti-inflammatory therapy
-immunologic enhancement
-oxygen therapy via insufflation
What are the supportive therapies for bacterial pneumonia?
-rest
-stress reduction
-nutrition
-adequate ventilation
-hydration
Which viruses are involved in viral pneumonia?
-EHV1
-EHV4
-EHV5
-equine influenza virus
-equine viral arteritis
What are the primary pathogens for fungal pneumonia?
-Blastomyces dermatitidis
-Coccidioides immitis
-Cryptococcus neoformans
-Histoplasma capsulatum
-Aspergillus spp.
-Pneumocystis carinii
What is important about Pneumocystis carinii?
it is an opportunist; if it is causing infection, it indicates that there is immune deficiency
What are the contributing factors to fungal pneumonia?
-exposure to large numbers of mycotic organisms in environment
-stabling of horses in moist environment
-prolonged administration of antibiotics
-immunosuppression
-neoplasia
What are the clinical signs of fungal pneumonia?
-chronic cough
-anorexia and weight loss
-exercise intolerance
-nasal discharge
-non-responsive to antibiotics
-pleural effusion
-tachypnea/resp distress
What are the findings on transtracheal wash that indicate fungal pneumonia?
-degenerate neutrophils
-yeast
-bacteria
Why must TTW and BAL be interpreted carefully when evaluating for fungal pneumonia?
fungi can be picked up incidentally from the nose and skew results
What findings on radiographs can indicate fungal pneumonia?
-circular masses
-accentuated interstitial pattern
-pleural effusion
How is fungal pneumonia treated?
months of antifungal medication
Which antifungals are used to treat fungal pneumonia?
-amphotericin B
-natamycin
-azoles, but not well absorbed in horses
Which parasite is able to cause pneumonia in horses?
Dictyocaulus arnfieldi
What are the characteristics of Dictyocaulus arnfieldi?
-donkeys and mules are asymptomatic carriers
-occurs in foals more than adults
-should always ask if horses are housed with donkeys/mules
What is the pathogenesis of Dictyocaulus arnfieldi?
-prepatent period of 2-4 months
-can have donkey-horse or horse-horse transmission
-adults live in airways and cause inflammation
What must occur in order for horses to acquire Dictyocaulus arnfieldi?
they must be on pasture, since the parasite has environmental requirements
How do earthworms contribute to Dictyocaulus arnfieldi spread?
earthworms can ingest the larvae and move across the pasture without harming the larvae
How does the fungus Pilobolus contribute to Dictyocaulus arnfieldi spread?
fungus develops on manure piles and disperses the larvae with its spores
What are the clinical signs of Dictyocaulus arnfieldi?
-possibly asymptomatic
-chronic cough
-bilateral nasal discharge
-increased resp rate and effort
-crackles and wheezes
-similar signs to asthma
How is Dictyocaulus arnfieldi diagnosed?
-TTW/BAL to look for eosinophils
-ID of parasite in sediment of centrifuged mucus
-Baermann fecal exam
How is Dictyocaulus arnfieldi treated and prevented?
-ivermectin or moxidectin
-separate horses from donkeys and other known carriers
