Biliary protozoa in a dog with acute cholangiohepatitis fed a raw food diet

Abstract A 1‐year 11‐month intact female Alaskan Malamute fed a raw food diet was referred to the Queen Mother Hospital for Animals for further investigation of hyporexia and increased hepatobiliary enzyme activities. Clinicopathological and imaging findings were consistent with cholangiohepatitis, with coccidial zoites identified on bile cytology. Polymerase chain reaction and amplicon sequencing from the bile identified Hammondia heydorni, a Sarcocytid coccidial protozoa with an obligate 2‐host life cycle. The dog was treated with clindamycin, marbofloxacin, ursodeoxycholic acid (UDCA) and S‐adenosylmethionine/silybin with complete clinical and biochemical resolution documented after 6 weeks. Infection with Hammondia spp. should be considered in patients receiving raw food diets in which coccidial zoites are identified in the bile, but the pathogenic potential of this organism is unknown and the possibility of its presence as a commensal cannot be discounted.


| INTRODUCTION
Hammondia heydorni is a cyst-forming coccidian parasite with a 2-host life cycle. Definitive host infection occurs by ingestion of an intermediate host. 1,2 Little is known about the pathogenicity of the Sarcocystid coccidian protozoa H. heydorni in dogs, but diarrhea is the most frequently reported clinical sign in clinical cases. 3,4 Other Sarcocystid coccidian protozoa have been associated with hepatitis in dogs, 5,6 with the presence of Hammondia species identified in bile from a dog with acute hepatitis 7 and Isospora spp. also documented in canine bile, 8 but the clinical relevance of these biliary protozoa is unclear.
We report the first case in which coccidial zoites of H. heydorni have been documented in the bile of a dog that was fed raw food with clinical, clinicopathological and imaging findings consistent with cholangiohepatitis.

| CASE DESCRIPTION
A 1-year 11-month, intact female Alaskan Malamute presented for further investigation of hyporexia, pigmenturia and increased hepatobiliary enzyme activities identified before referral. The dog had no history of travel outside of the United Kingdom and was fed a commercial raw food diet. On presentation, physical examination disclosed icteric sclera, mild cranial abdominal discomfort, and an increased body condition score of 8/9, but was otherwise unremarkable. Initial investigations included a CBC, serum biochemistry profile and abdominal ultrasonography. The CBC identified a mild neutrophilia (14.22 Â 10 9 /L; reference interval, 3.5-11.5 Â Sarcocystidae species have been described as a causative factor in hepatitis affecting companion animals, namely Toxoplasma in cats, and Sarcocystis and Neospora in dogs. Hammondia was historically not believed to be associated with disease in dogs, but recent literature suggests this organism may be an emerging pathogen. 1,3,4 Hammondiasis has been reported infrequently, often is associated with diarrhea, 4,11 and has been identified in dogs fed raw meat. 11  Feeding of raw diets is a rapidly growing trend with substantial concern regarding both the development of food-borne disease in pets and the risk to humans handling raw food products and in contact with animals fed such diets and their environment. 12 Several dangerous pathogens with zoonotic capacity have been identified in commercial raw food diets and raw meat, including extendedspectrum β-lactamase producing Enterobacterales, Salmonella species, Clostridium perfringens and several other bacterial and protozoal pathogens. [12][13][14][15] Biliary H. heydorni in the dog described here may represent a novel unusual infectious disease related to feeding of raw meat, but both the source of infection and the pathogenicity of H. heydorni in our case cannot be definitively proven.
A previous report in which Hammondia species were identified in the bile of a dog with acute hepatitis is similar to the case presented here, 7 in which marked increases in ALP and ALT activities were evident along with cytologic evidence of hepatic neutrophilic inflammation and biliary coccidial zoites. However, a limitation of the former report was the inability to distinguish H. heydorni from H. triffittae.
Both the aforementioned case and our case had biochemical and clinical resolution after treatment, having both received clindamycin, S-Adenosylmethionine/Silybin and a fluoroquinolone. Ursodeoxycholic acid was utilized in our dog for its cholerectic action, 16 given the ultrasonographic and biochemical evidence of cholestasis.
Interestingly, serology for Toxoplasma and Neospora were positive in both our dog and in another report 7 despite negative PCR, and subsequent identification of Hammondia. This finding suggests a likely degree of cross-reactivity in canine assays between Sarcocystidiae species, similar to what has been observed in ruminants and rodents. [17][18][19] It is not possible to conclude that hammondiasis was a definitive contributing factor to the cholangiohepatitis in our case, and clinical improvement could be attributed to treatment with marbofloxacin, ursodeoxycholic acid or S-Adenosylmethionine/Silybin or to spontaneous resolution, rather than resolution of hammondiasis secondary to treatment with clindamycin. A limitation of our report is that repeat cholecystocentesis to document persistence or resolution of To conclude, we describe the first report of confirmed H. heydorni in bile of a dog fed a raw food diet with suspected cholangiohepatitis.
This case adds to the body of evidence surrounding H. heydorni as an emerging organism of interest, although the clinical relevance of identification of this Sarcocystid organism in this case is unknown.

ACKNOWLEDGMENT
No funding was received for this study.

CONFLICT OF INTEREST DECLARATION
Authors declare no conflict of interest.

OFF-LABEL ANTIMICROBIAL DECLARATION
Authors declare no off-label use of antimicrobials.

INSTITUTIONAL ANIMAL CARE AND USE COMMITTEE (IACUC) OR OTHER APPROVAL DECLARATION
Authors declare no IACUC or other approval was needed.

HUMAN ETHICS APPROVAL DECLARATION
Authors declare human ethics approval was not needed for this study.