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Not eating: when to call the vet

Every pet has an off day now and then. Here’s when to call – for cats, dogs and young animals – and which signs can’t wait.

The short answer

If a cat hasn’t eaten for a day, call your vet the same day: just 24 hours without food can seriously harm an adult cat (Cornell Feline Health Center). If a dog hasn’t eaten for more than 24 hours, it should be examined (Texas A&M University). Young animals sooner: for kittens under 6 weeks, even 12 hours can be life-threatening. If a dog has a bloated belly or retches without vomiting, go to an emergency vet right away.

Cats: even one day counts

According to the Cornell Feline Health Center, not eating can seriously harm an adult cat after as little as 24 hours. So call your vet the same day.

Eating less is serious too. International Cat Care says a cat needs to see a vet urgently if its appetite has been reduced for three days or more. Overweight cats are especially at risk, because fat can build up in the liver (Merck Veterinary Manual, University of Illinois).

That’s why a cat should never go hungry, not even to lose weight.

Dogs: call after 24 hours

A dog that hasn’t eaten for more than 24 hours or seems lethargic should be examined (Texas A&M University).

If it isn’t eating and is vomiting or has diarrhea, call within 8 to 12 hours (Animal Medical Center New York).

Puppies and kittens: call sooner

Young animals have few reserves. For kittens under 6 weeks, even 12 hours without food can be life-threatening (Cornell). Small-breed puppies can develop low blood sugar in their first months (Merck Veterinary Manual).

If a young animal skips a meal or eats much less, it’s best to call the same day.

When it’s urgent

  • Emergency vet right away: a dog with a bloated, painful belly, restlessness or retching without vomiting (Merck Veterinary Manual).
  • Call today: vomiting for more than 24 hours or with blood, a painful belly, fever or severe tiredness (Cornell, Merck).
  • Call today: a cat that hasn’t eaten for a day, a dog for more than 24 hours, a young animal skipping meals.

What your vet will ask

  • Since when has your pet not been eating, or eating less?
  • Is it drinking normally?
  • Is it vomiting or does it have diarrhea?
  • Could it have eaten something unusual?
  • Has anything changed, such as the food?

Jot it down – it saves time on the phone.

Become too thin?

If your pet has lost weight for no clear reason or is too thin, your vet should examine it thoroughly (WSAVA, AAHA).

A very thin animal must not suddenly get a lot of food: vets start with a small part of the amount and increase it over several days (Merck Veterinary Manual, ASPCA). Your vet decides how much.

Questions

How long can a cat go without eating?

No longer than a day. Just 24 hours without food can seriously harm an adult cat (Cornell Feline Health Center), and for kittens under 6 weeks even 12 hours. Call your vet the same day.

How long can a dog go without eating?

If a dog hasn’t eaten for more than 24 hours, call your vet (Texas A&M University). Sooner if it’s vomiting, has diarrhea or seems lethargic, and go to an emergency vet right away if its belly is bloated or it retches without vomiting.

My cat is eating less than usual. Is that bad?

If it has been eating less for three days or more, it needs to see a vet urgently (International Cat Care). That’s especially important for overweight cats, because fat can build up in the liver.

Sources

Last checked: October 2026