Venereal spirochetosis of rabbits: description and diagnosis.

Venereal spirochetosis of rabbits was studied in naturally infected rabbits from an enzootically infected colony containing inbred, partially inbred, and mutant bearing rabbits, and in experimentally infected rabbits from a hysterectomy-derived colony. Naturally and experimentally induced genital lesions were similar clinically and histologically. The most common site of lesions in naturally infected rabbits was the vulva or prepuce. Other sites, in descending order of frequency, were anal region, nose, eyelid, and lip. Clinical appearance of lesions varied from erythematous macules or papules to erosions, ulcers, and crusts. Histological examination of lesions confirmed the presence of erosions, ulcers, and crusts and, in addition, revealed acanthosis and infiltration of the dermis by plasma cells and macrophages. Dark field examination of scrapings from lesions was superior to several other methods for detection of Treponema cuniculi in lesions. The rapid plasma reagin test detected more infected rabbits than examination of lesions. The frequency of false positive rapid plasma reagin tests was low. The frequency of false negative reagin tests varied with the stage of disease.