This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
The waste portions of meat and tallow, including the skin and fiber, have for years been imported from South American tallow factories in the form of blocks. Most of the dog bread consists principally of these remnants, chopped and mixed with flour. They contain a good deal of firm fibrous tissue, and a large percentage of fat, but are lacking in nutritive salts, which must be added to make good dog bread, just as in the case of the meat flour made from the waste of meat extract factories. The flesh of dead animals is not used by any reputable manufacturers, for the reason that it gives a dark color to the dough, has an unpleasant odor, and if not properly sterilized would be injurious to dogs as a steady diet.
Wheat flour, containing as little bran as possible, is generally used, oats, rye, or Indian meal being only mixed in to make special varieties, or, as in the case of Indian meal, for cheapness. Rye flour would give a good flavor, but it dries slowly, and the biscuits would have to go through a special process of drying after baking, else they would mold and spoil. Dog bread must be made from good wheat flour, of a medium sort, mixed with 15 or 16 per cent of sweet, dry chopped meat, well baked and dried like pilot bread or crackers. This is the rule for all the standard dog bread on the market. There are admixtures which affect more or less its nutritive value, such as salt, vegetables, chopped bones, or bone meal, phosphate of lime, and other nutritive salts. In preparing the dough and in baking, care must be taken to keep it light and porous.
DOG DISEASES AND THEIR REMEDIES:
See Veterinary Formulas.