Gingival fibromatosis (hereditary hyperplastic gingivitis) in a wild European red fox (Vulpes vulpes)

This report. describes a case of gingival fibromatosis in an otherwise healthy and well nourished wild European red fox (Vulpes vulpes), which was shot by a hunter and submitted to the state laboratory in the context of the rabies monitoring program of the federal state of Brandenburg, Germany. At necropsy, a severe papillomatous proliferation of the complete gingival tissue of the upper and lower jaw was present. This gingival proliferation had already resulted in malocclusion, loosening and loss of several incisival, premolar and molar teeth. Histologically, the primary lesion was a massive increase in the amount of collagen rich and relatively avascular connective tissue within the gingival lamina propria mucosae. A papillomavirus infection was excluded by electron microscopy, immunohistochemistry and molecular biological methods. The gingival lesions in the red fox are identical to those seen in hereditary hyperplastic gingivitis in farmed silver foxes and hereditary gingival fibromatosis in man. It is presumed that, in analogy to the genetic diseases in silver foxes and man, a still unidentified genetic defect is responsible for the development of the disease in the red fox, too.