Pancreatic and biliary duct Hammondia heydorni infection in a dog fed a raw elk-meat diet

We describe a 3-y-old Standard Poodle that was fed a raw elk-meat diet and developed anorexia, icterus, and markedly elevated liver enzyme activities. Histopathology of the pancreatic and liver biopsy specimens revealed lymphohistiocytic pancreatitis and hepatitis with intraepithelial protozoa. Histologically, Hammondia spp. are indistinguishable from Neospora caninum. Therefore, we employed PCR and amplicon sequencing to further investigate our case. Amplification and sequencing of the ITS1 marker matched 100% with Hammondia heydorni . Intrapancreatic involvement and the histopathologic features of hepatic and pancreatic H. heydorni infection have not been reported previously in dogs, to our knowledge. H. heydorni is a coccidian organism with an obligatory 2-host life cycle. The definitive hosts are dogs and coyotes; the intermediate hosts are mostly ruminants, including cervids. Ingesting tissue cysts within the skeletal muscle of the intermediate hosts leads to infection in the definitive hosts. H. heydorni has been considered clinically inconsequential; however, increasing reports note gastrointestinal and hepatic disease in dogs associated with this organism, and H. heydorni is considered an emerging pathogen in dogs. Infection in our case was associated with ingestion of raw cervid meat; cases of H. heydorni infection are invariably linked to ingestion of raw-meat diets.