Complete and balanced
A regulated claim that a food supplies every nutrient a pet needs, in the right proportions, as its only diet — the one label phrase that carries real weight.
Most words on a pet food bag are marketing. This one is not. To carry it, a food has to meet a published nutrient profile for a stated life stage, either by formulation or by a feeding trial, and the statement has to name which life stage it applies to.
Two things follow. A food labelled complete and balanced for growth is not the same product as one labelled for adult maintenance, and feeding the wrong one long-term is a real nutritional error. And anything sold as complementary — most treats, toppers and single-ingredient pouches — is by definition not designed to be the whole diet, however good the ingredient list looks.