Pancreatic and biliary duct <i>Hammondia heydorni</i> 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, <i>Hammondia</i> spp. are indistinguishable from <i>Neospora caninum.</i> Therefore, we employed PCR and amplicon sequencing to further investigate our case. Amplification and sequencing of the ITS1 marker matched 100% with <i>Hammondia heydorni</i>. Intrapancreatic involvement and the histopathologic features of hepatic and pancreatic <i>H. heydorni</i> infection have not been reported previously in dogs, to our knowledge. <i>H. heydorni</i> 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. <i>H. heydorni</i> has been considered clinically inconsequential; however, increasing reports note gastrointestinal and hepatic disease in dogs associated with this organism, and <i>H. heydorni</i> is considered an emerging pathogen in dogs. Infection in our case was associated with ingestion of raw cervid meat; cases of <i>H. heydorni</i> infection are invariably linked to ingestion of raw-meat diets.