Oslerus osleri (metastrongyloidea; filaroididae) in gray wolves (Canis lupus) from Banff National Park, Alberta, Canada.

Oslerus osleri is a filaroid parasite of the respiratory tract of canids. In North America, it is most commonly reported from coyotes (Canis latrans) and domestic dogs (Canis lupus familiaris), but reports in gray wolves (Canis lupus) are infrequent. We report a new geographic record for O. osleri in four gray wolves from Banff National Park, Alberta, Canada. Adult nematodes found in nodules in the submucosa of the trachea and bronchi were identified as O. osleri based on morphometry of spicules of males. We sequenced two segments of the genome of adult nematodes: a 1,111-base pair (bp) segment of the 18S region that was 100% identical to the 18S region of O. osleri from a coyote in California and a 537-bp segment that included the ITS-2 region and partial 5.8S and 28S genes. Histopathologically, there were submucosal nodules of adult nematodes surrounded by fibrosis and lymphoplasmacytic inflammation. These findings are consistent with O. osleri infections in other canids. The importance of this parasite in wild canid populations is unknown, but prevalence may be underestimated because many studies have focused on gastrointestinal parasites or used routine fecal flotation that has low sensitivity for this parasite. The ecology and population genetics of this parasite where multiple species of canids are sympatric warrant closer investigation to determine potential for interspecies transmission.