Diagnosing and managing canine eosinophilic bronchopneumopathy

A harsh, persistent cough with gagging and retching can signal this serious, but manageable disease. Here are the steps practitioners can to take to confirm a diagnosis and help improve a patient's clinical signs through corticosteroid therapy.
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Jun 01, 2010


Illustration by KO Studios
Canine eosinophilic bronchopneumopathy (EBP) is an important differential diagnosis for cough and dyspnea that practitioners frequently overlook because it is relatively uncommon. This condition, previously known as pulmonary infiltrates with eosinophils, has been defined as "a disease characterized by eosinophilic infiltration of lung and bronchial mucosa."1


Figure 1A & Figure 1B. Left lateral thoracic and ventrodorsal radiographs of a dog with eosinophilic bronchopneumopathy showing a diffuse bronchial pattern with pulmonary nodules. (Photos courtesy of Diagnostic Imaging Section, Veterinary Teaching Hospital, Purdue University.)
The inciting cause of the eosinophilic infiltration remains unknown in most cases. As such, EBP is considered an idiopathic disease.1 EBP differs from asthma in that spontaneous bronchial hyperreactivity and reversible airway obstruction (features that define asthma) are not typical components of this disorder.2 EBP has a great deal of relevance to practitioners as a condition that can be readily diagnosed and managed in a general practice setting with a favorable outcome in most cases. (See "The pathophysiology of eosinophilic bronchopneumopathy.")

CLINICAL PRESENTATION


Figure 1B (Photo courtesy of Diagnostic Imaging Section, Veterinary Teaching Hospital, Purdue University.)
EBP is most commonly seen in young adult dogs with an average age of 4 to 6 years.1,3 Females are affected more frequently than males.1,3 EBP has been described in Labrador retrievers, Alaskan malamutes, German shepherds, fox and Jack Russell terriers, dachshunds, Belgian shepherds, and Brittanies; Siberian huskies appear to be overrepresented.1,3-6 However, all breeds may be affected with this condition.

The most frequently observed clinical sign in dogs with EBP is cough, which is documented in 95% to 100% of cases.1,6 The cough is characterized as persistent and harsh and is typically followed by gagging or retching, likened to a "smoker's cough."1 Other common clinical signs include dyspnea, exercise intolerance, and nasal discharge that may be serous, mucoid, or mucopurulent.1,6 Lethargy and anorexia are usually not reported but may be noted if concomitant pneumonia is present.2 The clinical picture may vary from acute, life-threatening dyspnea to chronic, occasional cough.1,6,7

DIAGNOSTIC EVALUATION

Physical examination and laboratory evaluation


Figure 2A & Figure 2B. Bronchoscopy of a dog with eosinophilic bronchopneumopathy revealing yellow-green exudate within the bronchi. (Photos courtesy of Dr. Nolie Parnell, Clinical Associate Professor of Small Animal Internal Medicine, Department of Veterinary Clinical Sciences, Purdue University.)
Performing a thorough physical examination is crucial for differentiating respiratory disease from gastrointestinal disease, which also may manifest as gagging and retching. Moreover, physical examination may reveal clues that suggest pulmonary diseases other than EBP (e.g. cachexia with neoplasia or fever with pneumonia). Physical examination findings may range from no abnormalities to pronounced dyspnea or tachypnea. Likewise, thoracic auscultation results may be entirely normal or reveal increased lung sounds, crackles, or wheezes.1 As stated above, nasal discharge may be present.


Figure 2B (Photo courtesy of Dr. Nolie Parnell, Clinical Associate Professor of Small Animal Internal Medicine, Department of Veterinary Clinical Sciences, Purdue University.)
Results of a serum chemistry profile and urinalysis are typically normal in dogs with EBP only. A peripheral eosinophilia is not necessary for diagnosis of EBP as a complete blood count will reveal a mild to marked eosinophilia in only 50% to 60% of cases.1,3,6,7 A leukocytosis, neutrophilia, basophilia, or combination of these is also frequently noted.1,3,6 To assess for a parasitic respiratory infection, a fecal examination using a Baermann technique and a zinc sulfate centrifugation-flotation test should be performed in all dogs presented for evaluation of a cough. Similarly, heartworm testing is mandatory for all dogs undergoing diagnostic investigation for respiratory disease.