Clinicopathologic findings of naturally occurring Rabbit Hemorrhagic Disease Virus 2 infection in pet rabbits.

Abstract

Two pet rabbits were presented with an acute decrease in appetite and activity. Rabbit 1 showed severe hypothermia, bradycardia, arrhythmias, a heart murmur, dyspnea, occlusion of the nares with secretions, icterus, dehydration, and gaseous gastrointestinal dilation. The urine was dark yellow. Rabbit 2 was overweight, apathetic, and dehydrated; this animal presented with a heart murmur, gastric dilation, and intermittent nystagmus with dorsal strabismus in the right eye. Blood gas, electrolyte, hematology, plasma clinical biochemistry analysis, coagulation profile, plasma protein electrophoresis, urinalysis, and radiographic examinations were performed. The main shared findings were moderate thrombocytopenia, markedly decreased aspartate aminotransferase and alanine aminotransferase activities and fibrinogen concentrations, prolonged prothrombin and activated partial thromboplastin times, profoundly increased alkaline phosphatase and gamma-glutamyl transferase (GGT) activities, and high bile acid and bilirubin concentrations. Rabbit 1 also had respiratory acidosis, marked hypoglycemia, hyperphosphatemia, and a profoundly increased creatine kinase activity. Gastric dilation was observed on both radiographic exams. A low urinary pH of 5-6, marked bilirubinuria and proteinuria, and high urinary GGT levels were present in both patients. Marked icterus developed before death, which occurred within 22 and 30 hours post admission in rabbits 1 and 2, respectively. The necropsy of rabbit 1 showed a markedly accentuated hepatic lobular pattern, pulmonary hemorrhages, pericardial effusion with adhesions, peritoneal petechiae, and icteric and hemorrhagic abdominal fat. Histopathologic findings included hemorrhagic diathesis, severe centroacinar and midzonal hepatocellular necrosis, severe necrosuppurative bronchopneumonia, and moderate cardiomyocyte necrosis. A liver PCR assay was positive for Rabbit Hemorrhagic Disease Virus (RHDV) 2 (RHDV2) and negative for classic RHDV. This is the first description of the gross clinicopathologic abnormalities associated with naturally occurring RHDV2 infection in pet rabbits.