Pet nutrition is an important branch of veterinary science, but the pet food market is far more lightly regulated than human food, with extensive marketing claims divorced from scientific evidence. The foundational tool for evaluating pet food quality: the Association of American Feed Control Officials (AAFCO) nutritional standards are the most widely adopted reference framework — foods meeting AAFCO nutritional adequacy statements should satisfy cats’/dogs’ basic nutritional needs.
## Core Dog Nutrition Points
**Dogs are omnivores**: unlike cats, dogs have evolutionarily acquired the ability to digest starch (AMY2B gene expansion; amylase activity 28 times that of wolves), so grains (rice, oats, barley) are well-utilized energy sources for dogs. “Grain-free is more natural” is an over-marketed concept.
**Grain-Free and Dilated Cardiomyopathy (DCM)**: in 2018, the FDA issued a notice investigating the potential link between grain-free pet foods (particularly those with legumes and pulses as major ingredients) and canine DCM (heart disease). Investigation is ongoing (mechanism unclear), but until this issue is resolved, caution is recommended when selecting legume-first-ingredient grain-free dog foods, particularly for DCM high-risk breeds (Golden Retrievers, Labradors, Great Danes).
**Protein sources**: high-quality protein sources (real meat rather than “meat meal”) are key quality metrics. Ingredients lists are ordered by weight descending — if the first ingredient is “Chicken,” it contains more fresh chicken (~70% moisture); if “Chicken Meal,” higher protein density. Both can be quality protein sources.
## Core Cat Nutrition Points
**Cats are obligate carnivores**: cats lack multiple enzyme systems for synthesizing essential nutrients from plant precursors (taurine, arachidonic acid, vitamin A synthesis) — these must come directly from animal-source foods. “Vegan cat food,” even with synthetic nutrient supplements, has contested long-term safety. Cat hydration is an important health issue: cats’ natural food (prey) contains approximately 65-70% moisture, while dry food contains only approximately 10% — long-term dry-food-only feeding may increase chronic kidney disease (CKD) and urinary tract disease risk; recommend at least partial wet food feeding (canned/raw) or providing flowing water (cat water fountains).
See [Pet Health Prevention](https://sunqi.org/pet-health-prevention-en/) and [AAFCO Pet Food Standards](https://www.aafco.org/).
