Articular presentation of Mycobacterium avium ssp. avium infection in a golden eagle ( Aquila chrysaetos ) on the Isle of Lewis, Scotland

Summary A wild golden eagle ( Aquila chrysaetos) was found dead in poor body condition. On gross examination, the bird was emaciated, with damaged feathers and an enlarged right tibiofemoral joint due to multiple pale, smooth, nodular and plaque‐like masses. High numbers of acid‐fast bacilli were seen in the Ziehl–Neelsen‐stained smears from the mass, consistent with a severe articular infection caused by a Mycobacterium spp. However, no associated internal lesions were present. A PCR targeting the rpoB genetic marker and subsequent sequencing were used to confirm and identify the Mycobacterium spp. as Mycobacterium avium ssp. avium . The unusual presentation here of avian mycobacteriosis, lacking typical granulomatous lesions in internal organs, highlights that avian mycobacteriosis in wild raptors can differ from the typical presentations noted in domesticated avian species. In the absence of culture facilities, molecular tools can aid in rapidly confirming postmortem diagnoses and identifying the causative agent.