Taurine is an amino acid. Thiamine hydrochloride is a synthetic source of vitamin B1, thiamine. Thiamine mononitrate is a synthetic source of vitamin B1. Zinc carbonate is a source of the mineral zinc. Zinc oxide is a natural form of the mineral zinc.
Zinc sulfate is a synthetic form of the mineral zinc.
Blue No. 2 is thought to increase some animals' sensitivity to viruses. Yellow No. 5 is commonly used but has not been fully tested. Red No. 2 and Violet No. 1 were banned by the FDA in mid-1970s as possible carcinogens, but prior to that they were widely used in pet foods. The sugar adds palatability and moistness and aids in preventing bacterial contamination.