The Association of American Feed Control Officials (AAFCO) establishes nutritional adequacy standards that appear on virtually every commercial pet food label. When you see complete and balanced nutrition, that claim is backed by either AAFCO feeding trials or nutrient profile formulation.
As veterinarians, we field countless questions about pet food quality. Feeding trial statements indicate the diet was actually fed to dogs or cats for a defined period with documented health outcomes. Formulation-based claims mean the diet meets AAFCO nutrient profiles on paper but was not necessarily tested in live animals. Both are legally acceptable, but feeding trials provide stronger evidence of palatability and digestibility.
The guaranteed analysis lists minimum percentages of crude protein and fat, and maximum percentages of crude fiber and moisture. These are minimums and maximums, not exact values. A food claiming 26% protein may contain 28% or 32%—the manufacturer only guarantees it meets the minimum.
To compare foods accurately, convert to dry matter basis (DMB) when moisture levels differ:
- DMB % = (As-fed % ÷ (100 − moisture %)) × 100
- Example: 10% protein at 75% moisture = 40% protein DMB
Ingredients are listed by weight before processing. Chicken may appear first, but after cooking removes water, the actual dry matter contribution could be less than grains that follow. This is why chicken meal or chicken by-product meal often provides more protein per pound than whole chicken—the water has already been removed.
By-Product Myths Debunked: By-products include organ meats, blood, bone, and other parts not typically consumed by humans. In many cultures, these are prized ingredients. AAFCO defines by-products as secondary products from the primary processing of animal tissue. They are highly digestible and nutrient-dense. The myth that by-products are filler or low quality is not supported by nutritional science.
Warning: One of the most dangerous hidden ingredients is xylitol, a sugar alcohol used in sugar-free products. It is extremely toxic to dogs, causing rapid hypoglycemia and potentially fatal hepatic necrosis. Peanut butter marketed for humans often contains xylitol as a sugar substitute. Always advise clients to check ingredient lists on any human food given as treats. Use the Nutrition Label Scanner to scan product labels for toxic ingredients.
Other concerning ingredients to watch for include propylene glycol (toxic to cats), excessive sodium in renal-compromised patients, and certain artificial preservatives that may trigger sensitivities.
Advise clients to seek veterinary guidance when their pet has food allergies, chronic gastrointestinal signs, obesity, renal disease, or hepatic dysfunction. Prescription or therapeutic diets require professional oversight. For healthy pets, any AAFCO-compliant diet from a reputable manufacturer is a reasonable starting point.
- AAFCO feeding trials provide stronger evidence than formulation-based claims.
- Convert to dry matter basis (DMB) when comparing foods with different moisture levels.
- Chicken meal often provides more protein per pound than whole chicken.
- Xylitol is extremely toxic to dogs—always check peanut butter and sugar-free products.
- Recommend veterinary guidance for food allergies, GI signs, obesity, renal/hepatic disease.