The Effect of Various Fractions of Liver on Experimental Canine Blacktongue

Abstract

By careful observation, under controlled conditions, it has been possible to produce repeated attacks of experimental canine blacktongue and to compare the therapeutic effects of various dietary supplements derived from liver. Definite criteria for successful therapeutic results from a supplement administered for 10 days or less have been outlined, and the effects of various combinations of supplements tested. The method is suitable for the assay of blacktongue curative potency of any substance which can be administered to dogs. Varying the supplemental treatment in 152 attacks of experimental blacktongue in forty-five dogs gave results from which we conclude: a) that simple aqueous extracts of liver are potent in ‘cure’ of the condition; b) that extracts of liver prepared for parenteral use in pernicious anemia are only partially successful, even in huge dosage; c) that the residue from preparation of these parenteral liver extracts is potent in a dosage comparable to the amount of the same material which is potent for pernicious anemia and sprue in man; d) that parenteral extracts, in amounts which are alone ineffectual, may replace considerable amounts of the residue in combinations which produce successful therapeutic results. These results are not consistent with the possibility that nicotinic acid, which is also effective in experimental canine blacktongue, is present in therapeutically significant amounts in either or both fractions of liver tested. The results suggest that two substances, partially separable by the methods of fractionation in use, are present in liver, and that both are necessary for the elaboration of some compound (probably a nicotinic acid complex) which is potent in the cure of experimental blacktongue in dogs and pellagra in man.