Clinical and computed tomographic findings of rabbits with pulmonary emphysema

Introduction / Purpose:
Pulmonary emphysema (PE) is a rarely reported and poorly understood condition in pet rabbits. This retrospective study investigates clinical and computed tomographic findings of PE in rabbits.
Methods:
726 archived thoracic CT studies of 529 rabbits were reviewed, alongside their medical records for clinical data. CT studies were scored based on the type and lobar location of PE.
Results:
74 CT studies of 57 rabbits (10.7% of the population) were positive for PE. PE was
affecting most commonly the left cranial (52/74) and right cranial (38/74) lung lobes. Of those rabbits that underwent follow-up CT evaluation, pulmonary emphysema was stable in 7/13 and progressive in 6/13, but improved in none. Reason for initial presentation included upper/lower respiratory disease (19.3%/15.6%). Naso-ocular discharge (14.03%), dyspnoea (12.3%), and increased respiratory effort (14.03%) were the most common respiratory clinical signs. Eight rabbits presented with respiratory distress indicated by cyanosis (12.3%) and open-mouth breathing (3.5%) which were considered poor prognostic factors. Twenty-six rabbits (45.6%) were asymptomatic. Euthanasia resulting from respiratory disease was the outcome in 10/55 rabbits (17.5%).
Discussion / Conclusion:
Pulmonary emphysema is a relatively common condition in rabbits. The most common imaging finding is hypoattenuation of the pulmonary parenchyma, which can be focal, multifocal, or diffuse. It is frequently asymptomatic but clinical signs can include increased respiratory effort, naso-ocular discharge, and dyspnoea. Pulmonary emphysema should be considered as a differential diagnosis of respiratory disease in rabbits.