What does "complete" mean on cat food?

"Complete" means the food is formulated to meet all of a cat's nutritional requirements when fed as the sole diet, at the stated life stage. In the EU and UK, this is defined by FEDIAF nutritional guidelines. A food labelled "complementary" must be fed alongside other foods to avoid deficiency — treats, toppers, and most gravy pouches are complementary. Never feed a complementary food as the primary diet. Our wet, dry, or mixed feeding guide explains how to combine food types safely.

Are "meat and animal derivatives" acceptable in cat food?

"Meat and animal derivatives" is a legal EU/UK category that can include a wide range of animal-origin ingredients — muscle meat, organs, blood, bone meal — from one or more species. It is not inherently poor quality; organs are nutritionally dense. However, the formulation can vary batch to batch, and the lack of transparency makes it harder to identify ingredients if your cat has a specific sensitivity. Named ingredients (e.g. "chicken 40%") are more consistent and allow better dietary management.

How do I compare wet and dry food nutritionally?

Wet food is typically 75–82% moisture, making direct comparison of analytical constituents with dry food (8–12% moisture) misleading. To compare on equal terms, convert both to a dry matter basis: divide each nutrient percentage by (100 − moisture%) × 100. A wet food showing 10% protein at 78% moisture is actually 45% protein on a dry matter basis — higher than many dry foods. Our wet vs dry guide covers this in full.

Do I need to worry about grain in cat food?

Cats are obligate carnivores and have limited ability to digest starch efficiently, but moderate levels of grain-derived carbohydrates in an otherwise balanced complete diet are generally tolerated in healthy adult cats. The "grain-free" trend is not evidence-based for cats in the way it has been for dogs. More important than grain vs grain-free is overall protein quality and quantity — look for a named protein as the first ingredient. Cats with specific IBD presentations may benefit from hydrolysed or novel protein diets under vet guidance.

Reading Cat Food Labels: A Complete Guide

Complete vs complementary: the most important distinction

The single most important label term is whether a food is complete or complementary. This is a regulatory term under EU/UK retained pet food legislation, not a marketing claim:

Complete

Formulated to meet all nutritional requirements at the stated life stage when fed as the sole diet. Safe to feed as the cat's only food source. Must meet FEDIAF minimum nutrient profiles.

Complementary

Does not meet all nutritional requirements alone. Must be fed alongside other foods. Most treats, toppers, gravy pouches, and "sticks" are complementary. Feeding a complementary food as a sole diet will cause nutritional deficiency over time.

The ingredient list

Ingredients are listed in descending order of weight before processing. High-moisture ingredients (fresh meat) appear heavier than their post-cooking contribution. The first ingredient should be a named animal protein (chicken, salmon, turkey). Look for:

Named proteins ("chicken", "salmon", "duck") — specific, consistent across batches
"Meat and animal derivatives" — legally broad category; not harmful but variable; species may not be specified
Organ meats ("chicken liver", "chicken hearts") — nutritionally dense, appropriate inclusions
Taurine — cats cannot synthesise adequate taurine; it must appear as an additive in most foods as a safety net

The presence of grains, vegetables, or legumes is not inherently problematic in a complete diet — the overall profile matters more than any single ingredient. Our foods cats should never eat guide lists specific ingredients to avoid entirely.

Analytical constituents

The analytical constituents panel shows minimum or typical percentages of: protein, fat, crude fibre, moisture, and ash. These are the basis for comparing foods, but moisture content makes direct comparison between wet and dry foods misleading without conversion.

Dry matter conversion

To compare a wet food (e.g. 78% moisture, 10% protein) with a dry food (e.g. 10% moisture, 32% protein):

Wet DM protein = 10 ÷ (100 − 78) × 100 = 45.5%

Dry DM protein = 32 ÷ (100 − 10) × 100 = 35.6%

The wet food is actually higher in protein on a dry matter basis despite a lower as-fed percentage.

Energy density and portion calculation

Accurate portioning requires knowing kcal per 100g, not just grams. Some labels state this directly ("metabolisable energy: X kcal/100g"). If not stated, a rough estimate uses modified Atwater factors:

Protein: 3.5 kcal/g
Fat: 8.5 kcal/g
Carbohydrate: 3.5 kcal/g (calculate carbs as: 100 − protein − fat − fibre − moisture − ash)

Once you have kcal/100g, you can calculate how much food to feed against your cat's daily calorie target. Our feeding guide explains how to calculate daily kcal requirements and use the feeding calculator to check portions.

Life stage labelling

EU/UK regulations require foods to state the intended species and life stage. "All life stages" foods meet kitten requirements (the most demanding) and are safe for all ages. "Adult" and "senior" formulations are not always meaningfully different — some "senior" ranges are rebranded adult products with minor tweaks. FEDIAF does not define a minimum standard for "senior" as it does for kitten and adult. Compare the analytical constituents, not the life stage marketing.

Switching foods. When changing to a new food — even a better one — always transition over 7–10 days by gradually increasing the new food and reducing the old. Abrupt changes cause gastrointestinal upset in most cats. Our wet, dry, or mixed guide covers transition timing for changing between food formats.

Reading cat food labels: a complete guide

Complete vs complementary: the most important distinction

The ingredient list

Analytical constituents

Energy density and portion calculation

Life stage labelling

Frequently asked questions