Abstract
An enzootic lungworm infection caused by a nematode not previously found in the dog, and probably representing a new species in the Filaroides-Metathelazia group, was found during postmortem examination of Beagle dogs purchased from a commercial breeder. Abnormal respiratory signs were not present, and clinicopathologic tests did not aid in the antemortem detection of infected dogs. Lungworms were present only in alveoli and terminal and respiratory bronchioles. In the majority of dogs there was a focal, granulomatous reaction directed against the adult lungworm, but a remarkably broad spectrum of other pulmonary changes was also seen, including some that mimic drug-induced and neoplastic lesions. Preliminary evidence suggests this lungworm may be present in a number of kennels that breed Beagles for use in research.