Nutritional Dermatoses in Rats

Hitherto all scaly dermatoses produced in rats by means of diets have been broadly characterized as pellagra or pellagra-like. Failure properly and exactly to describe the scaly diseases of the rat and to differentiate one disease from another has led to confusion and controversy in the field of nutritional investigation. At least 3 scaly dermatoses can be produced in the rat and prevented or cured by nutritional means. They are due to (1) vitamin H deficiency (egg-white injury), (2) vitamin B₆ deficiency, and (3) lactoflavin deficiency. (1) Vitamin H 1 deficiency disease is the name given to the general disorder experimentally produced in the rat by inclusion of a high proportion (15 to 40%) of egg-white in an otherwise well-balanced diet which contains all the well-known vitamins. Administration of vitamin H cures this condition. Rats kept on a diet of this kind exhibit in from 4 to 6 weeks typical symptoms of sebor-rheid 2 dermatitis, such as erythema, intertrigo particularly around the neck and genitalia, a brown crusting chiefly over the back that is similar to “cradle cap,” and scaling that progresses from the areas of intertrigo to involve the entire surface of the body and that leads finally to a generalized exfoliative dermatitis. Generalized alopecia and exquisite pruritus are also manifest. The hind legs and the ears escape involvement. Excoriations heal slowly. Skin abscesses are rare; when present they are ecthyma-like. Mild sublingual ulcers are fairly common.

The microscopic picture reveals that in the earliest stages of the disease there is edema in the upper portion of the corium; there is also acanthosis with intercellular and intracellular edema. Altération cavitaire and spongiosis of the stratum spinosum precede the formation of intra-epithelial vesicles.