Production of Canine Blacktongue on Purified Diets

Abstract

Goldberger and coworkers 1 produced the canine disease black-tongue, on diets consisting principally of natural foodstuffs (largely corn, cow peas, and casein). They believed that the ability of certain foodstuffs to prevent the disease was due to their content of a specific heat-stable component of the vitamin B complex identical with the human pellagra-preventive (P-P) factor. The P-P factor has been rather generally considered 2 to be identical with the rat factor, vitamin G (B₂).

Certain doubts have been cast on this view of the production of blacktongue. Zimmerman and Buraek 3 maintained dogs on an “artificial, balanced ration adequate in all dietary essentials as far as is known except water-soluble, heat-stable vitamin B₂ (G),” and these dogs did not develop blacktongue but a different disease.

Rhoads and Miller 4 also reported that they were unable to produce blacktongue by feeding diets lacking in G (B₂). It has even been suggested 3 that blacktongue is due to multiple deficiencies of the Goldberger diet rather than to lack of a specific vitamin.

The demonstration of the multiple nature of the heat-stable fraction of the B complex has led to an explanation of some of these discrepancies. Birch, György, and Harris 5 fed 4 dogs on a “synthetic” basal ration, complete except for the B complex, supplemented with lactoflavin [now known to be the rat factor, vitamin G (B₂) 6 ] and highly purified vitamin B (B₁). Typical blacktongue appeared in each dog, proving conclusively that blacktongue is due to lack of some member of the vitamin B complex other than B (B₁) or G (B₂).

At the time of the appearance of the above work I had nearly completed an independent investigation on the production of blacktongue on “synthetic” diets. Four dogs were fed the following basal ration which is complete except for B vitamins: purified casein 19 parts, glucose 66, salt mixture (Osborne-Mendel) 4, cottonseed oil 8, and cod liver oil 3 parts.