Dorsal black skin necrosis in a Vietnamese pot‐bellied pig

Abstract

Background Thermal burns are an uncommon cause of injury in large animals. Case report A 10‐month‐old pet female black and white Vietnamese pot‐bellied pig presented to the emergency service with fever and erythematous to purpuric skin lesions affecting the intermandibular space and hocks. One week prior to the emergency visit, she had appeared restless and in pain. Two weeks following the emergency visit, she again presented to the large animal clinic with sloughing of the pigmented skin on her head, face, dorsal and lateral trunk sparing the nonpigmented skin and pigmented ears. The affected skin constituted ~40% of her total skin. Histopathological findings for affected skin included full‐thickness epidermal and partial to full‐thickness dermal coagulative necrosis with follicular epithelial mineralization, while that from normal‐appearing pigmented skin was within normal limits. A culture from a skin biopsy yielded meticillin‐resistant Staphylococcus aureus (ST‐72). Treatments included oral antibiotics, pain management, hyperbaric oxygen therapy and general anaesthesia to facilitate debridement. Healthy skin was often present when the necrotic skin was debrided, although in some areas the necrosis extended into the underlying fat. Complications that occurred during rehabilitation included intense pruritus that resulted in self‐trauma and the formation of a nasal fistula, which was later surgically corrected. Conclusions and clinical importance Cases of dorsal thermal necrosis in pot‐bellied pigs are uncommon in the literature. Based on the clinical presentation and lack of another identifying cause, the lesions were attributed to a sun‐induced thermal burn.

Dorsal thermal necrosis in dogs: a retrospective analysis of 16 cases in the southwestern USA (2009–2016)

“…In all previously reported cases, histopathological features of DTN have resembled other types of thermal burn injury . Histological findings from dogs with DTN included in the present study were consistent with these previous reports.…”

“…The one exception is a report of DTN in a brown‐coated dachshund . Full‐thickness necrosis of dorsal black‐haired skin analogous to canine DTN has also been recognized in a Vietnamese pot‐bellied pig with unlimited exposure outdoors in high ambient temperatures . Based on the previous reports of DTN, it has been suggested that dogs with darkly pigmented skin and hair are predisposed to DTN.…”

“…Exposure to high intensity sun and heat has been recognized as an uncommon cause of thermal injury in animals . Reports of solar‐induced thermal burns are limited, but all documented cases have been confined to the skin on the dorsal parts of the body . Consequently, this condition has been termed dorsal thermal necrosis (DTN) .…”

Solar‐induced dorsal skin necrosis in sheep

“…Dorsal thermal necrosis is an unusual condition characterized by solar‐induced thermal burn confined to pigmented skin along the dorsum . It has been reported on the dorsal black spots of a Dalmatian dog, in Dachshund dogs and other dark‐coated dogs, as well as in a Vietnamese pot‐bellied pig and in sheep shorn in summer in Australia . All cases occurred in animals with short hair or clipped coats and exposure to high sunlight intensity and ambient temperature.…”

“…Liver disease, photosensitizing plants or drugs can exacerbate UV light effects . The visible solar radiation (400–700 nm) preferentially absorbed by darkly pigmented skin, penetrates deeper skin layers, where it is converted into thermal energy and causes partial‐ to full‐thickness coagulative skin necrosis …”