Page 1582 - Cote clinical veterinary advisor dogs and cats 4th

794 Pneumonia, Aspiration

○ Both right and left lateral views should ○ Choice ideally based on C&S (respiratory PEARLS & CONSIDERATIONS
lavage)
be acquired. ○ Often more than one type of bacteria Comments
VetBooks.ir solidation in affected lung lobes. Changes present (Escherichia coli, Mycoplasma, • Because aspiration pneumonia rarely occurs
○ Alveolar or interstitial pattern, or con-
Pasturella, and Staphylococcus spp most
in the absence of an underlying cause,
found in the lobes that were dependent at
common)
the time of aspiration; if the patient was
animals should be evaluated for risk factors.
conscious during aspiration, abnormalities ○ Initial choice pending culture often • Absence of known regurgitation or vomiting
are often seen in the right middle, right parenteral broad-spectrum antibiotics (e.g., does not rule out aspiration pneumonia
cranial, or caudal portion of the left cranial combination of ampicillin 22 mg/kg IV because these events can be silent.
lung lobe. q 8h and enrofloxacin 5 mg/kg IM or IV • Cough suppression is contraindicated.
q 12h [dogs] or 5 mg/kg q 24h [cats])
Advanced or Confirmatory Testing • Physiotherapy: coupage, movement Prevention
• Pulse oximetry and/or arterial blood gas • Saline nebulization • Address underlying diseases that predispose
(ABG) analyses to assess oxygenation • If aspiration is suspected but respiratory to aspiration.
• Respiratory (tracheal or bronchoalveolar [p. distress is absent, careful observation without • Fast animals at least 6 hours before general
1073]) lavage (submit samples for cytological additional treatment may be sufficient. anesthesia, and use properly inflated, cuffed
exam and culture and susceptibility [C&S]) endotracheal tubes during anesthesia.
○ Neutrophilic inflammation ± bacteria Chronic Treatment • For animals at high risk, consider administra-
○ Hemorrhage • Prevent further aspiration or reduce severity tion of antacids (proton pump inhibitors)
○ Particulates/debris of injury from aspiration (see Prevention to increase gastric pH or administration of
○ Lipid-laden macrophages below). prokinetic agents (e.g., metoclopramide) to
• Search for predisposing cause of aspiration • Discontinue oxygen when PaO 2 remains enhance gastric emptying and increase lower
(e.g., acetylcholine receptor antibody titer for above 65 mm Hg and the animal can breathe esophageal sphincter tone. Unfortunately,
myasthenia gravis–related megaesophagus) comfortably without it. these measures have not been shown to
• Traditionally, antibiotics continued for 3-4 improve outcomes in humans at high risk for
TREATMENT weeks; a shorter duration of therapy may be aspiration, and perioperative metoclopramide
adequate. administered to dogs undergoing unilateral
Treatment Overview arytenoid lateralization did not reduce risk
Severity of aspiration pneumonia varies, and Nutrition/Diet of aspiration pneumonia.
therefore intensity of therapeutic intervention Animals with severe ongoing vomiting/ • Use caution with forced administration of
varies as well. Adequate oxygenation must be regurgitation should not be fed by mouth. drugs or foodstuffs.
ensured and further aspiration prevented when • Feeding tubes should not cross the lower
possible. Antimicrobial drugs may be needed to Behavior/Exercise esophageal sphincter unless gastric evacuation
treat secondary bacterial infection. A step-by- • Recumbent animals with severe pneumonia is required.
step approach to treatment is shown on p. 1440. should NOT be allowed to lie with the most
functional lobes on the down side. Technician Tips
Acute General Treatment • Movement may facilitate beneficial cough • Sudden respiratory signs in hospitalized
• If aspiration is witnessed, immediately and airway clearance. animals should be brought to the attending
suction material from pharynx/airways, and veterinarian’s attention immediately.
ensure airway patency. Possible Complications • For animals with regurgitation, maintain an
• If respiratory distress or evidence of • Administration of high concentrations of upright position with the head and chest
hypoxemia exists, administer supplemental oxygen for prolonged periods can contribute elevated above the stomach for at least 30
oxygen using the lowest effective oxygen to respiratory epithelial injury. minutes after oral feeding.
concentration (typically, FIO 2 ≈40%) (p. • Parenteral fluids/colloids may worsen • Use appropriately sized endotracheal tube
1146). noncardiogenic pulmonary edema. with cuff inflated during general anesthesia.
○ If PaO 2 < 60 mm Hg or if PCO 2
> 60 mm Hg despite oxygen supple- Recommended Monitoring Client Education
mentation, intubate for positive-pressure • Oxygenation (ABG or pulse oximetry), When a predisposing cause is not reversible
ventilation. depending on severity of disease, q 4-24h (e.g., idiopathic megaesophagus), repeated
• Bronchodilators may relieve bronchospasm until normalized aspiration events are likely.
(cats especially): terbutaline 0.01 mg/kg SQ, • Thoracic radiographs: frequency determined
inhaled albuterol (nebulized or by metered by severity or progression of clinical signs; SUGGESTED READING
dose inhaler), or aminophylline (dosage ideally repeated 1-2 weeks after discontinu- Tart KM, et al: Potential risks, prognostic indicators,
depends on preparation) ation of antibiotics and diagnostic and treatment modalities affecting
• IV crystalloid fluids • CBC: rechecked at least weekly until survival in dogs with presumptive aspiration
○ Maintenance rate of 60 mL/kg/day after leukocytosis resolved pneumonia: 125 cases (2005-2008). J Vet Emerg
correction of dehydration; more if there Crit Care 20:319, 2010.
are ongoing losses. CAUTION: excessive PROGNOSIS & OUTCOME AUTHOR: Leah A. Cohn, DVM, PhD, DACVIM
parenteral fluids may precipitate edema EDITOR: Megan Grobman, DVM, MS, DACVIM
in the damaged lung. • Depends on volume and character of
• Antimicrobials are often suggested because aspirated material but generally good
secondary infection is common. • Prognosis worsens when > 1 lobe involved

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