What Is Your Diagnosis?

Jorge R. Walker VCA Advanced Veterinary Care Center, 15926 Hawthorne Blvd, Lawndale, CA 90260.

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Reid K. Nakamura VCA Advanced Veterinary Care Center, 15926 Hawthorne Blvd, Lawndale, CA 90260.

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History

A 7.0-kg (15.4-lb) adult castrated male mixed-breed dog was referred because of a 3-month history of progressive tachypnea and dyspnea. The dog had been treated with several courses of antimicrobials (of uncertain type, dose, and duration), which had not improved the clinical signs. Radiographs of the thorax were obtained (Figure 1).

Figure 1—
Figure 1—

Right lateral (A) and ventrodorsal (B) radiographic views of the thorax of a 7.0-kg (15.4-lb) adult castrated male mixed-breed dog evaluated because of a 3-month history of persistent tachypnea and dyspnea that was unresponsive to treatment with multiple courses of antimicrobials.

Citation: Journal of the American Veterinary Medical Association 245, 3; 10.2460/javma.245.3.277

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →

Radiographic Findings and Interpretation

Two spherical air-filled encapsulated structures are evident in the cranial and middle lobes of the right lung (Figure 2). The smaller structure measures 1.9 × 1.5 cm, and the larger structure measures 6.0 × 5.2 cm. Both lesions consist of a thick soft-tissue opaque wall with an irregular inner margin. An alveolar pattern is superimposed on the cranioventral aspect of the cardiac silhouette, whereas the rest of the pulmonary parenchyma has a diffuse bronchointerstitial pattern.

Figure 2—
Figure 2—

Same radiographic images as in Figure 1. Notice the 2 spherical air-filled encapsulated structures evident in the cranial and middle lobes of the right lung (arrows). The smaller structure measures 1.9 × 1.5 cm, and the larger structure measures 6.0 × 5.2 cm. Both lesions consist of a thick soft tissue opaque wall with an irregular inner margin. An alveolar pattern is superimposed on the cranioventral aspect of the cardiac silhouette, whereas the rest of the pulmonary parenchyma has a diffuse bronchointerstitial pattern.

Citation: Journal of the American Veterinary Medical Association 245, 3; 10.2460/javma.245.3.277

Differential diagnoses for the encapsulated cavitary lesions in the pulmonary parenchyma included pulmonary abscess, granuloma, bullae, or neoplasia.1,2 The differential diagnoses for the cranioventral alveolar pattern and diffuse interstitial pulmonary parenchyma include diffuse bronchopneumonia, chronic bronchitis, or pulmonary fibrosis.2 Thoracic ultrasonography was performed and revealed that the lesions contained echogenic effusion and gas. The cardiac structures were unremarkable, but the tracheobronchial lymph nodes appeared enlarged.

Treatment and Outcome

Recommendations for further evaluation included thoracic CT or surgical exploration. Given the guarded prognosis, the owner elected to have the dog euthanatized but permitted a necropsy.

The lungs were diffusely hemorrhagic and pale, and the large cystic lesion was noted in the middle lobe of the right lung, whereas the smaller lesion was identified in the cranial lobe of the right lung. Both were well encapsulated, and incision into the cystic structures revealed moderate amounts of foul-smelling purulent material and a large quantity of gas. The entire right lung was submitted for histologic analysis, and microbial culture of the purulent material was performed. Histologic evaluation of the pulmonary parenchyma revealed severe diffuse bronchopneumonia, and the tracheobronchial lymph nodes had findings consistent with reactive tissue secondary to chronic antigenic stimulation. Microbial culture of the purulent fluid revealed a mixed population of organisms identified as an Enterococcus sp and Escherichia coli; both organisms were resistant to several antimicrobials.

Comments

Pulmonary abscesses have been rarely reported in the veterinary literature.1,3 In human medicine, they are classified as primary when they develop without a predisposing condition or secondary if they occur as a result of a congenital lung abnormality, neoplasia, or a foreign body.4,5 The pathogenesis of a pulmonary abscess involves an area of initial pneumonia that leads to necrosis, cavitation, and abscess formation.5 In human medicine, treatment of pulmonary abscesses involves antimicrobial treatment for an extended duration.4,5 In veterinary patients, pulmonary abscesses have typically been managed surgically.1,3

  • 1. Robinson DA, DeNardo GA, Burnside DM. What is your diagnosis? Pulmonary abscess. J Am Vet Med Assoc 2003; 223: 12591260.

  • 2. Lamb CR. The canine and feline lung. In: Thrall DE, ed. Textbook of veterinary diagnostic radiology. 5th ed. St Louis: Saunders Elsevier, 2007; 591608.

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  • 3. Murphy ST, Ellison GW, McKiernan BC, et al. Pulmonary lobectomy in the management of pneumonia in dogs: 59 cases (1972)1994). J Am Vet Med Assoc 1997; 210: 235239.

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  • 4. Patradoon-Ho P, Fitzgerald DA. Lung abscess in children. Paediatr Respir Rev 2007; 8: 7784.

  • 5. Brook I. Lung abscess and pleural empyema in children. Adv Pediatr Infect Dis 1993; 8: 159176.

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