Skin biopsy helped diagnose Trichinella britovi infection in hunting

Abstract

A six-year-old mixed-breed female hunting dog, which has been imported from Bulgaria to Germany, was admitted to a private veterinary clinic presenting a swelling (approx. 10 ×10 x 1 cm) with ulceration of the skin on the left abdominal flank. The dog evidenced difficulty to climb the stairs. The mass including skin and subcutaneous tissues was surgically removed and submitted for routine histological examination. Microscopically, a severe pyogranulomatous to mixed-cellular and lymphoplasmacytic inflammation, with demarcating fibrosis, involving cutis, subcutis and cutaneous muscle was observed. Multiple cyst-like structures (∼0.25 mm diameter) with an eosinophilic hyalinised wall, containing nematode larvae sections (∼26 µm wide) were detected intralesional, and a Trichinella infection was suspected. Consequently, DNA was extracted from formalin-fixed paraffin-embedded tissues and a multiplex PCR for Trichinella species/genotype identification was performed. After electrophoresis, two bands of 129 and 253 bp were observed, which corresponds to the banding pattern of T. britovi. Trichinella T8 and T9 show a similar banding pattern; however, these genotypes are assumed to exclusively circulate in sub-Saharan Africa and Japan, respectively. The localisation of Trichinella in the cutaneous muscle, and the high degree and extension of inflammatory reaction observed are unusual. Consumption of hunted prey was assumed as the most probable source of infection. Trichinella spp. should be considered in the differential diagnosis of nematodes, which may be observed in cutaneous and muscular biopsies in dogs.