Complete vs Complementary Dog Food: What the Labels Actually Mean

Written by Lucy Fitzgerald, Founder, WYLDR. Reviewed by Katie McCaul, RNutr, The Pet Diet.

The short answer: Under UK law, a complete feed is one that, by its composition, is sufficient for a daily ration on its own. A complementary feed has a high content of certain substances but is sufficient for a daily ration only when used in combination with other feed. Treats, toppers and daily supplements are complementary. It is a statement about the product's role in the diet, not about its quality.

Two words on a bag of dog food do more work than any of the marketing around them, and most owners have never had them explained. "Complete" and "complementary" are not adjectives a brand chooses. They are legal designations with definitions written into law, and knowing which is which tells you more about what you are buying than any claim on the front of the pack.

The legal definitions, word for word

In short: Both terms are defined in Regulation (EC) No 767/2009, which applies in the UK as assimilated law. Complete means sufficient for a daily ration on its own. Complementary means sufficient only in combination with other feed.

Here they are as written, from Article 3(2) of the Regulation:

Complete feed is "compound feed which, by reason of its composition, is sufficient for a daily ration."

Complementary feed is "compound feed which has a high content of certain substances but which, by reason of its composition, is sufficient for a daily ration only if used in combination with other feed."

Read those twice, because the whole thing turns on one phrase: sufficient for a daily ration. A complete food is designed to be everything a dog eats in a day. A complementary food is designed to sit alongside something else.

Note what the complementary definition actually says: "a high content of certain substances". That is not a euphemism for "less good". It describes a product that concentrates on some things rather than covering everything, which is exactly what a topper, a treat or a supplement is meant to do.

What each one looks like in practice

In short: Complete foods are the main meal. Complementary feeds are everything else you put in the bowl.

Complete feeds include most complete dry foods, complete wet foods, and complete raw or freeze-dried meals. If it is intended to be your dog's entire diet, it should say complete.

Complementary feeds include treats and biscuits, chews, meal toppers, mixers, daily supplements and powders, bone broths, goat's milk, and single-ingredient extras. None of these are designed to be a whole diet, and none of them are allowed to claim they are.

The distinction is about design intent, not merit. A high-quality topper is a complementary feed. So is a cheap biscuit. The label tells you the role, not the standard.

The mistake worth avoiding

In short: Feeding a complementary feed as though it were complete. That is the actual risk the designation exists to prevent.

The designation is a safety measure. If a product is not formulated to meet a dog's full daily needs and someone feeds it as the whole diet, the dog will be short of things over time. That is why the law makes brands say which one they are selling, and why "complete" cannot be used loosely.

The practical rule: build the diet on a complete food. Add complementary feeds on top of it, within the small share of daily intake sensibly reserved for extras. Do not swap a meal for a topper.

If you are unsure whether your dog needs anything on top at all, our guide to do dogs need supplements works through that properly.

How to read a pack

In short: Look for the word "complete" or "complementary" on the pack. If neither appears, ask the brand. Do not infer it from the marketing.

Four things worth doing when you pick up a bag or a tub:

1. Find the designation. It is usually near the composition or the feeding guidelines rather than on the front. If a pack does not say "complete", treat it as not complete.

2. Read the feeding guidance. A complete food gives daily amounts by body weight, intended to be the whole ration. A complementary feed gives a smaller amount described as an addition.

3. Ignore the front of the pack for this purpose. "Complete nutrition", "full spectrum", "everything your dog needs" and similar phrasing is marketing language and is not the legal designation.

4. Check the composition list. Ingredients are listed in descending order by weight, which tells you what the product is mostly made of.

Is complementary food worse than complete food?

In short: No. They answer different questions. One asks "can this be the whole diet", the other asks "what does this add to it".

This is the misunderstanding worth clearing up, because "complementary" reads as a downgrade and is not one.

A complete food has to cover every base, which means breadth. A complementary feed can concentrate on a few things and do them properly, which is the whole point of a topper or a supplement. Judging a supplement for not being complete is like judging a vitamin D tablet for not being dinner.

What the designation genuinely tells you is how to use the product. What it does not tell you is anything about ingredient quality, sourcing or how well the thing is made. For those, you read the composition and ask the brand.

Where WYLDR fits

WYLDR's Every Dog Every Day is a complementary feed. It is designed to sit alongside your dog's normal food, not to replace it, and we will never describe it as complete, because it is not. That is the correct designation and it is also the honest one: a five-ingredient daily supplement is not a diet and was never meant to be.

Frequently asked questions

What does complementary dog food mean?
Under Regulation (EC) No 767/2009, which applies in the UK as assimilated law, a complementary feed is compound feed which has a high content of certain substances but which, by reason of its composition, is sufficient for a daily ration only if used in combination with other feed. In plain terms, it is designed to be fed alongside a complete food, not instead of it.

What does complete dog food mean?
The same Regulation defines a complete feed as compound feed which, by reason of its composition, is sufficient for a daily ration. It is designed to be a dog's entire diet without anything else being needed.

Is complementary dog food bad for dogs?
No. Complementary is a statement about a product's role in the diet, not its quality. Treats, toppers, chews and supplements are all complementary feeds. The only real risk is feeding one as though it were a complete diet.

Can I feed only complementary food to my dog?
No. A complementary feed is not formulated to meet a dog's full daily needs on its own. It should be fed alongside a complete food.

How do I know if my dog's food is complete or complementary?
The pack must say. Look near the composition or the feeding guidelines rather than the front of the pack. If the word "complete" does not appear, treat the product as not complete and check with the brand if you are unsure.

Are dog treats complementary feed?
Yes. Treats, biscuits, chews, toppers and supplements are all complementary feeds, because none of them are formulated to be a dog's whole daily ration.

Sources

• Regulation (EC) No 767/2009 on the placing on the market and use of feed, Article 3(2)(i) and 3(2)(j), as published on legislation.gov.uk in assimilated UK form: link
• FEDIAF, Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs, September 2025 edition: link
• FEDIAF, Code of Good Labelling Practice for Pet Food, October 2019: link