Suspect poisoning? US: ASPCA Poison Control (888) 426-4435 · UK: 01202 509 000 · Severe symptoms → nearest emergency vet now.

My small dog ate a mouldy protein bar that was left out overnight. What should I do?

Dogs · Food safety

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

Short answer

This is urgent. Mould adds another risk, but the primary danger is that many protein bars contain xylitol or chocolate, both of which are highly toxic to dogs. Contact your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 immediately. Do not wait for symptoms to appear.

Protein & energy bars — Food safety facts

Do not feed · Dogs · full breakdown on the linked food page

Very often sweetened with xylitol or coated in chocolate. Treat every bar as toxic until you read the label.

Dogs and cats carry the same rating (Do not feed), so the notes below hold for either pet.

Protein & energy bars should not be given to dogs at all. Even a small amount can do harm, so there is no portion small enough to be safe.

Do not induce vomiting and do not give milk or oil to “dilute” it. Note the food and roughly how much was eaten, then call your vet or a pet poison hotline and follow their advice on whether to bring the pet in straight away.

Why these cautions matter

Even a gram or two of xylitol can trigger a sharp drop in a dog's blood sugar, and larger exposures go on to damage the liver.

Theobromine is the part that hurts. Pets clear it far more slowly than people do, so it builds up and reaches the heart and nervous system.

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

The full verdict, portion guidance and serving notes are collected on the Protein & energy bars food facts page.

Open the full food page: Protein & energy bars food facts →