RHDV2 epidemic in UK pet rabbits. Part 1: clinical features, gross post mortem and histopathological findings

Abstract

To report clinical features, gross post mortem and histopathological findings from an investigation into sudden or unexpected death in rabbits that was undertaken during an outbreak of rabbit haemorrhagic disease. Materials and MethOds: Using a standard protocol, veterinarians were invited to submit case histories and results of their post mortem examination of pet rabbits that died unexpectedly. Histopathological examination of heart, lungs, liver, spleen and kidney samples was collated with macroscopic appearance and clinical details. results: Hepatocellular necrosis, characteristic of rabbit haemorrhagic disease, was observed in 185 of 300 (62%) submissions, often accompanied by glomerular thrombosis and changes in other organs. Evidence of rabbit haemorrhagic disease was not apparent on histopathology in 113 of 300 (38%) rabbits. Gross post mortem examination by veterinary practitioners did not always reflect reported histopathological changes. No macroscopic abnormalities were seen in 78/185 (42%) of rabbit haemorrhagic disease cases. Rapid death and death of other rabbits in the household were common features of rabbit haemorrhagic disease. Ante mortem clinical signs included anorexia, collapse, lethargy, seizures, icterus, bleeding from the mouth, dyspnoea, hypothermia, pyrexia, bradycardia or poor blood clotting. clinical iMpOrtance: Rabbit haemorrhagic disease can be suspected from a history of sudden death, especially if multiple rabbits are affected. There is not always macroscopic evidence of the disease but histopathology is useful to support or refute a diagnosis of rabbit haemorrhagic disease and provide information about other causes of death. (RHDV) is a calicivirus of the genus Lagovirus that targets hepatocytes and cells of the mononuclear phagocytic system, such as Kupffer cells, circulating monocytes, alveolar macrophages and endothelial cells (Ramiro-Ibáñez et al. 1999, Neimanis et al.

An outbreak of rabbit hemorrhagic disease (RHD) caused by <i>Lagovirus europaeus</i> GI.2/rabbit hemorrhagic disease virus 2 (RHDV2) in Ehime, Japan

“…The pathological findings were similar to those of typical RHD caused by classical RHDV and RHDV2 [ 1 , 3 , 5 , 14 , 16 , 20 ], including necrotizing hepatitis, disseminated intravascular coagulation and hemorrhage in the organs. Decrease in number of lymphocytes was also observed in lymphatic organs.…”

A Potential Atypical Case of Rabbit Haemorrhagic Disease in a Dwarf Rabbit

“…Different clinical presentations and disease progression can occur with RHDV2 [ 9 , 10 , 11 , 12 ] and those variations can be associated with strain. The incubation period of RHD ranges between 1 and 3 days.…”

“…These animals often die some weeks later, due to liver disease [ 18 ]. Although the study of the disease has been expanded by animal experimentation, the characterisation of natural infection is far less known [ 10 , 11 , 19 , 20 ].…”

“…The terms peracute, acute and chronic are of clinical use but not always reflected in distinct necropsy findings and specific histopathological patterns, meaning that it is possible to find sudden death associated with peracute widespread hepatocellular necrosis or with more chronic changes such as inflammation or fibroplasia [ 10 ].…”

“…Veterinarians should be aware that despite necropsy and histopathology findings may be suggestive of RHD, since microscopic changes are usually present and, in many cases, macroscopic changes can also be seen [ 10 ], laboratory confirmation is always required for a conclusive diagnosis.…”