Kibble
Extruded dry food is the most studied format by a wide margin. It is complete, affordable, shelf-stable, and convenient. Those are not small things.
The legitimate concern about kibble is what high-heat extrusion does to nutrients. Temperatures above 120°C can reduce the bioavailability of certain vitamins and denature proteins, and some extrusion processes produce Maillard reaction compounds, the result of proteins and sugars reacting under heat, whose long-term effects in pets are not well characterized. A 2024 University of Illinois digestibility study found that extruded diets generally had the lowest macronutrient digestibility compared to frozen raw, freeze-dried raw, and fresh formats tested in the same conditions.
That said, digestibility is not the whole story. Kibble meets AAFCO nutritional standards, has decades of feeding trials behind it, and the dogs eating it are, as a population, doing fine. "Lower digestibility" does not mean "harmful." It means less of what goes in comes out as usable nutrition — a real difference, but a calibrated one.
■ Filed under Nutrition. Corrections: corrections@proactivepethealth.com