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I've been mixing a tablespoon of ketchup into my 14 kg mixed-breed dog's kibble every evening for the past three months — is this doing any harm over time?

Dogs · Food safety

Last reviewed: 2026-09-05 · Reference ranges: ASPCA, Pet Poison Helpline & Merck Veterinary Manual

Short answer

It can be. A tablespoon daily adds up — over three months your dog has consumed a significant amount of hidden salt, sugar, and onion powder, all of which accumulate. Onion powder in particular is toxic to dogs in repeated doses, and the chronic sodium load stresses the kidneys and heart. Watch for increased thirst, frequent urination, vomiting, or loss of appetite. Switch to plain, unseasoned food and mention the ketchup habit at your next veterinary check-up.

Ketchup — Food safety facts

Feed with care · Dogs · full breakdown on the linked food page

Sugar, salt and onion powder in a small package. Not a treat.

Dogs and cats carry the same rating (Feed with care), so the notes below hold for either pet.

Ketchup is not poisonous to dogs, but it is easy to over-feed. Rich fat, salt or seasoning can bring on vomiting or diarrhoea within a day, and repeated large portions are a recognised trigger for pancreatitis.

If it ate some before you noticed, watch for vomiting, diarrhoea, loss of appetite, unusual tiredness or a painful, swollen abdomen over the next 24 hours. A one-off small amount in a healthy adult usually passes with water and rest; repeated exposure, a puppy or kitten, a senior, or a pet with an ongoing illness is a reason to call your vet the same day.

Why these cautions matter

Garlic and onion damage a pet's red blood cells and can bring on anaemia. Signs are often delayed for several days, so looking fine straight afterwards does not rule it out.

A heavy salt load drives up thirst and urination, and in the worst cases leads to sodium ion poisoning, which is a genuine emergency.

Added sugar brings empty calories, and over months that means weight gain and dental disease — both far harder to undo than to avoid.

Ketchup can turn up now and then, but not as a daily habit: keep the rest of the day's food unchanged and watch the next walk and the stool that comes with it.

The full verdict, portion guidance and serving notes are collected on the Ketchup food facts page.

Open the full food page: Ketchup food facts →