Hepatic leptospiral infections in dogs without obvious renal involvement

Abstract

BackgroundReports of chronic hepatitis in dogs caused by Leptospira spp. are confined to small case series. Fluorescence in situ hybridization (FISH) allows the identification of spirochetes in liver samples. Consequently, this technique may help elucidate the role of Leptospira spp. in cases of chronic hepatitis.ObjectivesTo describe cases of hepatic leptospirosis in dogs diagnosed by FISH and subsequent polymerase chain reaction (PCR) speciation, with the absence of clinically relevant renal involvement.AnimalsTen client‐owned dogs.MethodsRetrospective case series from the University of Cambridge presented between 2013 and 2016 or cases consulted by telephone advice during this time period. Cases were selected based on histopathologically confirmed granulomatous hepatitis and leptospiral organisms identified by FISH and PCR speciation (Leptospira interrogans/kirschneri).ResultsAll cases had increased liver enzyme activities, and FISH in combination with PCR speciation‐confirmed infection with L. interrogans/kirschneri. Four dogs underwent repeat liver biopsy, FISH and PCR speciation 4‐15 months after initial presentation and doxycycline treatment with 1 dog undergoing repeat sampling at necropsy. Three dogs that underwent repeat biopsy remained positive for L. interrogans/kirschneri infection. Six dogs were alive at the time of manuscript preparation and 4 dogs were euthanized as a result of progressive liver disease.Conclusions and Clinical ImportanceThe presence of hepatic leptospiral organisms may be associated with chronic granulomatous hepatitis without clinical evidence of renal involvement. Further studies are necessary to elucidate the etiological role of these organisms in the disease.

ACVIM consensus statement on the diagnosis and treatment of chronic hepatitis in dogs

“…Sporadic cases of CH have been associated with other infectious agents. Leptospirosis causes acute hepatitis and there is some evidence it can induce a chronic pyogranulomatous response . Bacillus piliformis , Helicobacter canis , and Bartonella spp have been identified in dogs with CH, but the evidence that these bacteria are the cause is not compelling .…”

“…Acid fast stains for mycobacteria and periodic acid Schiff or silver stains can detect fungi. Gram staining or fluorescent in situ hybridization (FISH) can detect bacteria. Immunohistochemical staining can detect viruses and protozoa.…”

“…Discussion of these interventions is beyond the scope of this consensus statement and readers are referred to reviews and recent book chapters . In some cases, treatment of the inciting infectious agent (eg, leptosporosis) may lead to clinical remission of CH, whereas in other cases full remission may not be achieved, possibly as a result of pathogen‐induced self‐perpetuating immune disease …”

“…Leptospirosis causes acute hepatitis and there is some evidence it can induce a chronic pyogranulomatous response. [49][50][51] Bacillus piliformis,…”

“…A transient acquired Fanconi-like syndrome characterized by euglycemic glucosuria may develop in dogs with CuCH and in other toxin-induced liver injuries when concurrent renal tubular injury occurs. 34,39,[49][50][51][135][136][137][138]159,168 The glucosuria in dogs with CuCH resolves with recovery from acute injury.…”