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31 Canine Chronic Bronchitis 307

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Figure 31.2 Computed tomography slice of the thorax showing a
Figure 31.1 Thoracic radiographs with a diffuse bronchial pattern “ground‐glass” appearance.
evidenced by increased “donuts and tramlines.”

airway collapse is suspected. Ultrasound of the thoracic as collapsing trachea/bronchi, obstructive intraluminal
cavity may assist with diagnostic sampling of isolated masses or granulomas caused by some parasites, and for-
lesions that are observed on radiographs (masses or con- eign bodies.
solidation), or when pockets of pleural effusion are iden- Transtracheal washes, endotracheal washes, and blind
tified; however, it does not assist in the diagnosis of CCB. or visualized bronchoalveolar lavages are very useful in
Computed tomography (CT) is widely used in people characterizing the type of inflammation present in the
with airway disease, and is becoming more popular in airways, and for the diagnosis of CCB. Samples should be
veterinary medicine for the evaluation of canine bron- submitted for bacterial cultures and cytology (fungal cul-
chial disease. The increased resolution of CT com- tures should be submitted when appropriate). The air-
pared to radiographs and the ability to perform 3D way sampling technique chosen often reflects clinician
reconstructions may prove to be more sensitive for the preference, and availability of supplies and equipment
diagnosis of CCB, and allow earlier detection and (see Box 31.3 for a detailed description of techniques).
treatment of the disease (Figure 31.2). Diagnostic CT Cytologic samples should be immediately placed into
scanning in veterinary medicine does require brief EDTA tubes, and processed promptly to avoid changes
general anesthesia, and if permissible should be com- in cell counts and appearance. In cases where analysis
bined with evaluation of laryngeal function, collection will be delayed, a small portion of the sample should be
of airway cytology samples, and bronchoscopy for a centrifuged, decanted, and a direct smear of the superna-
complete airway evaluation. tant and precipitation should be prepared. Evaluation of
If available, bronchoscopy is the preferred technique to respiratory cytology from dogs with CCB typically
evaluate and visualize the airway. A recent study showed reveals a predominant neutrophilic infiltrate with exces-
that patients with CCB often demonstrate an irregular sive mucus (Figure 31.3), small numbers of lymphocytes,
mucosal surface without the glistening seen in healthy eosinophils, goblet cells, ciliated and epithelial cells, and
airways. Most airways were also noted as having a granu- a variable number of alveolar macrophages. Samples that
lar mucosal appearance with a roughened texture, show a marked eosinophilia should be suspected of hav-
increased amounts of mucus, hyperemia of mucosal ves- ing an eosinophilic bronchopneumonopathy, rather than
sels, and partial collapse of larger airways during expira- CCB. Bacterial cultures should be submitted in all cases;
tion secondary to weakened walls. Bronchial dilation in however, the role of bacteria is unclear, as colonization is
patients with bronchiectasis can also be noted in CCB common, but may not reflect a clinical infection.
patients. Bronchoscopy is also beneficial for the diagno- Pulmonary function testing is widely used in human
sis or exclusion of some other large airway diseases such medicine to better characterize the severity of and specific