Cutaneous lesions in pet rabbits following subcutaneous administration of a novel bivalent vaccine against myxomatosis and rabbit haemorrhagic disease

Background: A novel bivalent vaccine to protect against myxomatosis and rabbit haemorrhagic disease is commercially available for pet rabbits. Hypothesis/Objectives: To describe the appearance of cutaneous lesions arising in pet rabbits positive for myxoma virus (MV) by RT-PCR evaluation shortly after vaccination. Animals: Four pet rabbits presenting with papular, crusting skin lesions ~10 days after vaccination. Methods: Histological evaluation of formalin-fixed skin biopsies obtained from lesional skin (case 1). Real-time polymerase chain reaction (RT-PCR) evaluation of paraffin-embedded tissue from skin biopsies (case 1) and crusts obtained from the lesion surface (cases 2-4) for myxoma virus are reported as cycle threshold (C_t) values. Results: Lesions affecting the ear pinna, dorsal aspect of the nose, vulva and/or conjunctiva are reported. Histopathological findings included severe ulcerative, necrotizing dermatitis and intralesional cytoplasmic inclusion bodies in myxoma cells. DNA was amplified from all the paraffin-embedded skin biopsies (C_t = 34-35) and crusts (C_t = 20-24). Conclusions and clinical importance: Although a wild virus challenge cannot be definitively excluded, veterinarians and pet-owners should be aware that cutaneous lesions have been observed after vaccination with this novel vaccine in low numbers of rabbits.