Caudal Necrosis in Suckling Rats

Abstract

THE communication by Njaa et al.¹ concerning the presence of ‘ringtail’ in newborn rats has prompted us to report similar observations in the colony maintained at these Laboratories. During the winter of 1954–55 signs of ‘ringtail’ were noticed in many suckling rats. Generally, these symptoms were seen in 8-day-old young rats, the first signs being a marked scaliness of the tail and reddening of the tail tip (Fig. 1). In many cases the condition of the tail deteriorated, resulting in necrosis followed by its severance from the body. Microscopic examination of sections of the tails revealed in the early stages a marked hyperkeratosis and parakeratosis (Fig. 2). There was œdema (spongiosis) and hyperplasia of the prickle cell layer, resulting in acanthosis. In some of the specimens, the prickle cells at all levels contained large amounts of keratohyaline granules. The hair follicles were slightly dilated and were filled with keratinized invaginations of the cornified layers of the epidermis. The corium was œdematous and often congested with blood. In the more advanced lesions, there was extensive eosinophilic necrosis of both the epidermis and the corium, accompanied by leucocytic infiltration. In general, these histological characters closely resemble those observed in the ring tails of rats born to mothers deprived of essential fatty acids².