P‐37 Dermoid sinus in Rhodesian ridgeback dogs

Abstract

Dermoid sinus (DS) is a congenital defect occurring with increased frequency in the Rhodesian ridgeback. The Swedish Rhodesian ridgeback population constitutes approximately 2000 dogs (1990–2000) and 8–10% of these dogs are suspected to be DS‐positive. The aim of this study was to further understand the aetiology of DS. Importantly, DS has been documented in several other dog breeds and our studies may have general impact for the health of domestic dogs. From seven litters (74 dogs), a total of 10 Rhodesian ridgeback dogs diagnosed as DS‐positive were subjected to necropsy. Six of the dogs were female. The dogs were between 11 and 42 days old. Six dogs had DS located at the cervical vertebra, and four had DS located at the lumbar vertebra. The DS lesions extended between 1.0 and 6.5 cm, and all identified DS lesions were associated with a skin opening. Five dogs were diagnosed with type I (attachment to/ending at the supraspinous ligament), one dog had a DS identified as type II (DS connected to the supraspinous ligament via a fibrous strand), and the remaining four dogs were diagnosed with type IV (DS penetration of the spinal cord). In six cases the DS lesion was fully pigmented, partially pigmented in two cases, and nonpigmented in two dogs, both of which were brown‐nosed. Five dogs were from two separate litters. DS locations in the siblings were approximately identical; however, differences in extension and pigmentation were apparent. Funding: Swedish Kennel Club, Swedish Rhodesian Ridgeback Club.