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Pneumonia, Bacterial 795

Pneumonia, Bacterial Client Education
Sheet
VetBooks.ir Diseases and Disorders
HISTORY, CHIEF COMPLAINT
BASIC INFORMATION
and initiate local inflammatory responses:
Chief complaint may be related to pneumonia defense mechanisms, bacteria can proliferate
Definition or the predisposing disease: ○ Common isolates in dogs and cats include
Inflammation of the pulmonary parenchyma • Pneumonia Escherichia coli, Klebsiella, Bordetella,
(small airways, interstitium, and alveoli) from ○ Cough (absence of cough does not rule Pasteurella, Mycoplasma spp, and Staphy-
bacterial infection out pneumonia) lococcus spp. Polymicrobial infection is
○ Nasal discharge ± sneezing common.
Epidemiology ○ Exercise intolerance ○ Acutely fatal pneumonia caused by
SPECIES, AGE, SEX ○ Anorexia, lethargy Streptococcus equi subsp zooepidemicus
Dogs are diagnosed more often than cats. ○ Hemoptysis (uncommon) and associated with fever, hemothorax,
Puppies acquired from community situations ○ Acute death (uncommon) and bleeding into airways can occur in
(shelters, pet stores) are more likely to have • Predisposing disease dogs from dense housing situations.
pneumonia from Bordetella bronchiseptica than ○ Regurgitation ○ Regionally endemic bacterial diseases,
from other pathogens. Bacterial pneumonia ○ Vomiting such as plague and tularemia, can cause
secondary to congenital defects (e.g., primary ○ Recurrent/persistent infections (usually pneumonia.
ciliary dyskinesia) is more common in young respiratory but occasionally other) • Local inflammatory responses cause pul-
animals, but bacterial pneumonia occurs at any • Mild, vague signs (e.g., delayed postoperative monary lesions, impair lung function, and
age and in either sex. recovery) may be the earliest manifestations contribute to respiratory and systemic disease
of the onset of bacterial pneumonia as a manifestations.
GENETICS, BREED PREDISPOSITION complication of another disorder (e.g., sepsis,
Breed or genetic predispositions associated systemic inflammatory response syndrome, DIAGNOSIS
with underlying primary diseases or associated multiple organ dysfunction syndrome).
conditions. Irish wolfhounds are reported to • Absence of clinical signs of respiratory disease Diagnostic Overview
be at increased risk. does not exclude the diagnosis; some animals Definitive diagnosis of bacterial pneumonia
with pneumonia demonstrate no clinical hinges on demonstration of bacteria by culture
RISK FACTORS signs. and sensitivity testing (C&S, most sensitive)
Any disease that increases the potential for or cytologic exam of respiratory wash samples.
aspiration: PHYSICAL EXAM FINDINGS Pursuit of an underlying or concurrent disease
• Laryngeal disease: laryngeal paralysis post Physical exam may be unremarkable or may that increases risk of bacterial pneumonia is
tieback surgery, laryngeal neoplasia, etc. reflect only signs related to an underlying strongly encouraged.
• Dysphagia predisposing disorder. Lack of physical exam
• Gastroesophageal reflux abnormalities referable to the respiratory system Differential Diagnosis
• Esophageal disease (p. 873): esophagi- cannot exclude the diagnosis. Findings are Many diseases share clinical and diagnostic
tis, megaesophagus, stricture, foreign variable but often include similarities:
body • Cough (hemoptysis possible) • Noninfectious inflammatory respiratory
• Altered consciousness • Nasal discharge diseases
• Chronic vomiting • Pulmonary auscultation • Pulmonary neoplasia
Any disorder that compromises respiratory ○ Loud or harsh bronchovesicular sounds • Respiratory parasites
defenses: ○ Crackles or wheezes, sometimes focal • Pulmonary edema
• Bronchial masses or foreign bodies ○ Focal absence of breath sounds • Fungal pneumonia, particularly blastomycosis
• Bronchiectasis • Fever (≈50%) and coccidioidomycosis in dogs
• Viral respiratory infection (e.g., distemper) • Tachypnea
• Congenital immune deficiencies • Increased respiratory effort or overt respira- Initial Database
• Immune suppression tory distress (p. 879) • CBC: inflammatory leukogram (with or
• Primary ciliary dyskinesia without left shift) expected, although not
Exposure, especially in dense housing condi- Etiology and Pathophysiology seen in all cases
tions, to other animals with respiratory signs • Bacterial pneumonia is most often a com- ○ Neutropenia is possible, especially with
may be a risk factor for B. bronchiseptica, plication of another disease that disrupts or sepsis. Conversely, bacterial pneumonia
Mycoplasma spp, or streptococcal pneumonia. overwhelms mechanical or immunologic pul- can develop secondary to primary neu-
monary clearance and defense mechanisms: tropenic disorders (e.g., myelosuppression
ASSOCIATED DISORDERS ○ Aspiration of gastric or oropharyngeal from chemotherapy).
• Sepsis contents • Serum biochemical profile/urinalysis: often
• Systemic inflammatory response syndrome ○ Impaired mucociliary clearance normal unless sepsis/systemic inflammation
• Multiple organ dysfunction syndrome ○ Impaired reflex closure of the glottis present
• Respiratory foreign body (recurrent ○ Absent or impaired cough reflex • Thoracic radiographs
pneumonia) ○ Abnormal immune function: innate or ○ Obtaining right and left lateral and ventro-
• Bronchial obstruction (foreign body, mass) acquired dorsal (VD) or dorsoventral (DV) views is
• Hemothorax (uncommon) • B. bronchiseptica can cause disease as a primary recommended because infiltrates may be
pathogen in dogs or cats without other apparent only in nondependent lung.
Clinical Presentation underlying risk factors or concurrent disease. ○ Minimally, two views (at least one lateral
DISEASE FORMS/SUBTYPES • Bacteria most often enter lungs through and either VD or DV) is necessary in all
Bronchopneumonia involves inflammation of airways but can enter hematogenously. With cases. Three views (right and left lateral and
airways and alveolar/interstitial compartments. impaired or overwhelmed clearance and either VD or DV) are strongly encouraged.

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