Development and Cure of “Ring-tailed” Condition in Rats on Vitamin B 6 Deficient Diets

In the course of an experiment in which sheep and cow rumen contents were being assayed for vitamin B₆ by a modification of the method of Dimick and Schreffler 1 we observed, in addition to the usual dermatitis of the face, ears and paws, ring-like (see plate I) lesions on the tail. This condition was first noted after the rats had been on the depletion diet for a period of 5 to 6 weeks and it developed in about 10 out of 100 animals used during the depletion period of approximately 7 weeks.

The basal diets used had the following composition:

In the first assay, using diet A. factor II was supplied by feeding 0.5 cc daily of a liver filtrate concentrate prepared from Lilly Liver Extract Powder 343∗ by 5 treatments with fuller's earth after the method of Lepkovsky, Jukes and Krause. 3 The filtrate secured by this procedure was further treated with 8 volumes of 95% ethanol and the resulting precipitate was discarded. The final filtrate was concentrated under reduced pressure to the point where 1 cc represented 2 g of the original liver extract powder. In the second assay using diet B a filtrate was used which had been prepared from Armour's Liver Extract 70 A.S.† by similar treatment. This preparation was fed at a level of 0.2 cc daily since preliminary experiments showed that this amount supplied sufficient factor II to satisfy the growth requirement of the rat.

Basal diet B contained 4% hydrogenated cottonseed oil and 4% lard. This change was made to avoid the possibility of a deficiency of unsaturated fatty acids in the diet. Since no difference was noted in the response of the rats in the two assays it is believed that both diets were equally satisfactory.