Dermal fibrosis in a rabbit

SIR, - A four-year-old, male, lop-eared rabbit was presented at this surgery on May 31, 2000, for the cleaning of faeces matted around its perineum. During handling for treatment, a marked thickening of the dorsal skin was noted in a plaque which extended from the neck to the rump (graduated edge) and down to the centre of each flank (distinct edge). The skin surface and fur density appeared normal throughout. Full thickness biopsies were taken from the centre and one edge of the plaque and sent to Idexx Laboratories. Both showed prominent, thick, dermal Collagen. Hair follicles were scattered and small. In the central biopsy there was moderate, superficial follicular keratosis and slight surface scaling. There was no inflammatory infiltrate in the dermis. There was no folliculitis and no parasites, fungi, yeasts or bacteria were seen. The rabbit was fit and well and the skin changes had not been noticed by the owner. It had previously been seen here in December 1999 with suspected cheyletiellosis, which responded to a single injection of subcutaneous ivermectin. No skin thickening was noted at the time. The rabbit's incisors were extracted in July 1999; they were mal-aligned following a fall in 1997. Glucose saline was administered subcutaneously after this Operation. The rabbit has been fed mainly on a proprietary rabbit mix in the past. Any observations from colleagues as to the possible causes of this fibrosis or what might happen next would be very welcome.