Why mould matters more than the granola itself
The visible mould you saw is just the surface issue — the real concern is what grows invisibly inside the bar. Unlike humans, cats lack enzymes to break down many mould byproducts, so even a few licks can deliver concentrated toxins. Your cat’s small size means those mycotoxins hit harder per pound of body weight than they would in a larger animal.
Watch for subtle changes first: is your cat turning away from food it normally loves, or hiding more than usual? These can be early red flags before vomiting or diarrhea appear. Since the exposure happened overnight, the clock started ticking hours ago — don’t wait for severe symptoms if you notice small behavior shifts.
The 24-hour window for mould reactions
Mycotoxin symptoms typically appear within 12-24 hours, but sometimes take longer to manifest. Your cat may seem fine initially, then suddenly develop tremors or excessive drooling as the toxins circulate. Keep a log of any changes, even minor ones like increased thirst or irregular litter box habits.
Unlike food poisoning from bacteria, mould toxicity doesn’t always cause immediate gastrointestinal upset. Neurological signs like unsteady walking or dilated pupils warrant an emergency vet visit immediately, even if no vomiting has occurred. Have the granola bar wrapper handy to check for other risky ingredients.
When granola ingredients compound the problem
Many mouldy granola bars also contain hidden dangers like raisins or chocolate chips that might not be visible after partial consumption. Check the ingredient list for these toxins — if present, your cat is facing multiple threats simultaneously. Even tiny amounts of raisins can trigger kidney failure in cats.
The combination of mycotoxins plus potential chocolate or raisin toxicity creates a cascade effect. Your vet may recommend blood tests sooner rather than later to monitor kidney function, since early intervention greatly improves outcomes. Don’t assume that because only a small amount was licked, the risk is minimal.
Preventing future kitchen hazards
Cats are drawn to the oils and fats in granola bars, so this won’t be the last time yours investigates human snacks. Store all such items in sealed containers well above counter height — feline thieves can open drawers and cabinets you thought were secure. Consider keeping a pet-safe treat jar as decoy.
If you frequently leave food out, train yourself to do a "cat sweep" before leaving the kitchen. Look for anything mouldy, chocolate-based, or raisin-containing that might have fallen where paws can reach. A moment of prevention saves hours of worry and potential vet bills later.
The full verdict, portion guidance and serving notes are collected on the Granola food facts page.