In the fiercely competitive pet-food industry, inventing a hit product takes a lot of trial and error not to mention plenty of pooch and feline focus groups. One thing the Iams scientists know is that dogs and cats rarely order from the same menu. Cats like foods acidic and prefer a sort of glassy texture. Dogs won't go near such froufrou fare, preferring things sweet or salty and enjoying both rough and creamy textures.
The question of kibble dimensions goes beyond the matter of size. Dogs prefer their kibbles amorphously shaped and dense. Iams once tried square kibbles, but they hurt the animals' mouths. Cats like their kibbles thinner and don't mind if the shapes are better defined.
Nutrition is an even greater challenge. The best source of fiber for pets appears to be beet pulp, a conclusion Iams reached by measuring everything that went into and, significantly, came out of test animals. Older animals need added nutrients, such as fats and proteins, they have trouble making on their own.
Taste-testing all these foods is a tricky business. Most dogs and cats for reasons known only to them prefer to eat from bowls placed on one side of their face or the other. An animal that appears not to like a food might simply be a righty being fed from the left. Some studies take place in people's homes, where pets and their owners are watched at mealtime. Humans, Iams has found, like to see dogs wag their tails while they're eating. "Then we know," says Diane Hirakawa, Iams' chief of R. and D., "when the dog sees the product, that tail better be wagging." Iams may not know why animals eat the chow, but it knows who buys it.