Canine adenovirus type 1 (CAdV-1) in free-ranging European brown bear (Ursus arctos arctos): A threat for Cantabrian population?

Canine adenovirus type 1 (CAdV-1) is responsible for infectious canine hepatitis. The disease has been described in captive American black bear (Ursus americanus) and European brown bear (Ursus arctos arctos), with just one recently reported case in a cub of a free-ranging brown bear (Ursus arctos horribilis) from Alaska. The aim of this work is to summarize findings related to presence and associated mortality of CAdV-1 in 21 free-ranging Cantabrian brown bears (Ursus arctos arctos) submitted to necropsy in Asturias and Castilla y León (northwestern Spain) from 1998 to 2018. On the basis of the anatomopathological findings and laboratory results three free-ranging brown bears died due to infectious canine hepatitis, which is to our knowledge the first description of death due to this disease in free-ranging bears in Europe. Gross lesions consisted of petechial haemorrhages and congestion in different internal organs, haemorrhagic fluid in internal cavities, friable and yellowish liver and thickening of gall bladder. Microscopic lesions were observed mainly in liver, kidney and brain and consisted of multifocal necrosis of cells with presence of basophilic intranuclear inclusions. Immunohistochemical (IHC) and real-time polymerase chain reaction (qPCR) techniques were used to assess the presence of CAdV-1 in paraffin-embedded liver samples. Viral antigens were detected by IHC labelling within hepatocytes and Küppfer cells in the three animals. The presence of viral DNA was confirmed by qPCR in one of them. In order to evaluate the circulation of CAdV-1 in brown bears, a retrospective study was performed using both IHC and qPCR techniques in 11 and 12 additional brown bears, respectively. An extra brown bear was found positive by IHC. This study shows that CAdV-1 surveillance of brown bears and sympatric carnivores should be considered as major concern for the monitoring the population evolution throughout time in this endangered species.

[Infectious canine hepatitis in 4 dogs in Switzerland]. / Hepatitis contagiosa canis Infektion bei 4 Hunden in der Schweiz.

Infectious canine hepatitis in 4 Dogs in Switzerland. Four dogs presented with nonspecific symptoms of lethargy, vomiting, diarrhea, fever and weakness. Laboratory results were consistent with hepatopathy and disseminated intravascular coagulation. Three dogs died, one survived. In the three deceased dogs, a diagnosis of infectious canine hepatitis (ICH) was made based on histological findings and positive immunhistochemistry results for canine adenovirus-1 (CAV-1). In the surviving dog, an antemortem diagnosis of ICH was determined via positive polymerase chain reaction results from blood, occular, nasal and preputial discharge as well as from urine. Since the introduction of widespread vaccination, the incidence of CAV-1 infection in dogs is low. However, the disease has not been eradicated and should be considered when clinical signs consistent with ICH are present.