Page 369 - Small Animal Internal Medicine, 6th Edition

CHAPTER 22 Disorders of the Pulmonary Parenchyma and Vasculature 341

intolerance, and respiratory distress. Cough is less common bronchoscopy to search for airway abnormalities or foreign
in cats with pneumonia. Systemic signs may include lethargy, bodies, conjunctival scrapings to look for distemper virus,
VetBooks.ir anorexia, fever, and weight loss. The animal may have a serologic or PCR tests to detect specific viral or fungal organ-
isms, and hormonal assays to determine whether the animal
history of chronic airway disease or regurgitation. Cats, par-
ticularly kittens, from stressful housing situations (e.g., over-
briefly in Chapter 21. Diagnostic evaluation for aspiration
crowding) appear predisposed to develop pneumonia as a has hyperadrenocorticism. Ciliary dyskinesia is discussed
result of Bordetella infection. Dogs with CIRDC may have a pneumonia is discussed in the section dedicated to aspira-
recent history of harsh cough and a history consistent with tion pneumonia.
exposure, as described in Chapter 21. Other potential pre-
disposing factors, as listed in the preceding section, are Treatment
pursued through careful history taking.
Fever may be noted on physical examination but is identi- Antibiotics
fied in only about half of patients. Crackles and occasionally Treatment for bacterial pneumonia consists of antibiotics
expiratory wheezes may be auscultated, with abnormal lung and supportive care, with follow-up evaluation (Box 22.1).
sounds often prominent over the cranioventral lung fields in The antibiotic sensitivity of involved organisms is difficult to
patients with infection of airway origin. predict. Gram-negative infection and infection with multiple
organisms are common. Antibiotics are initially selected on
Diagnosis the basis of severity of clinical signs and cytologic character-
Bacterial pneumonia is diagnosed on the basis of the com- istics (i.e., morphology and gram-staining) of organisms
plete blood count (CBC), thoracic radiographic findings, found in pulmonary specimens. Antibiotic selection is sub-
and results from tracheal wash fluid cytologic analysis and sequently modified, as needed, according to clinical response
bacterial culture. A CBC showing neutrophilic leukocytosis and sensitivity data from bacterial cultures of pulmonary
with a left shift, neutropenia with a degenerative left shift, or specimens.
moderate to marked neutrophil toxicity is supportive of bac- The extent to which an antibiotic can penetrate into the
terial pneumonia. However, a normal or stress leukogram is airway secretions does not need to be a major consideration
as likely to be found. in patients with bacterial pneumonia. Antibiotics generally
Abnormal patterns on thoracic radiographs vary with the achieve concentrations within the pulmonary parenchyma
underlying disease. The typical abnormality is an alveolar
pattern, possibly with consolidation, which is most severe in
the dependent lung lobes (see Fig. 20.5). Increased bronchial
and interstitial markings are often present. Infection second- BOX 22.1
ary to foreign bodies can be localized to any region of the
lung. An interstitial pattern alone may be present in animals Therapeutic Considerations for Bacterial Pneumonia
with early or mild disease or in those with infection of hema-
togenous origin. A bronchial pattern alone may be present Antibiotics
in animals with a primarily bronchial infection. Radiographs Ideally, selected on basis of results from Gram staining
are also evaluated for the presence of megaesophagus and and culture and sensitivity testing of pulmonary
other extrapulmonary disease. specimens. See text for specific guidelines.
Ideally, pulmonary specimens are evaluated cytologically
and microbiologically (bacterial and, ideally, Mycoplasma Airway Hydration
cultures or polymerase chain reaction (PCR)) to establish a Maintenance of systemic hydration
Saline nebulization
definitive diagnosis and provide guidance in antibiotic selec-
tion. To maximize the diagnostic yield, specimens should be Physiotherapy
collected before antibiotic therapy is initiated. A tracheal Turning of recumbent animals every 1 to 2 hours
wash specimen is generally sufficient. Septic neutrophilic Mild exercise of animals in stable condition
inflammation is typically found in animals with bacterial Coupage
pneumonia, and growth of organisms on bacterial culture is
expected. Examination of a gram-stained preparation will Bronchodilators
provide early guidance in antibiotic selection pending results As needed, particularly in cats
of culture and will assist in the identification of anaerobes or Oxygen Supplementation
other organisms that may not be easily grown in culture (e.g.,
Mycobacteria, filamentous organisms). As needed
A conscientious effort is made to identify any underlying AVOID
problems. In some animals, such as those with megaesopha- Diuretics
gus, the initiating cause is obvious. Further diagnostic tests Cough suppressants
are indicated in other animals, depending on the results Corticosteroids
of the clinicopathologic evaluation. These may include