Why overnight peanuts worry us more than fresh ones
When peanuts sit out, especially in humid conditions, invisible mould spores can start producing aflatoxin long before you see any fuzz. A 12 kg dog eating a handful means enough toxin could be present to stress their liver, even if the nuts looked normal. Unlike immediate poisoning, aflatoxin damage builds quietly over days, so early signs are easy to miss.
Dogs process toxins differently based on size—your pup’s weight puts them in a middle zone where symptoms might not appear right away but could still escalate. Watch for subtle changes like skipping meals or less energy before more obvious yellowing appears. The liver tries to compensate until it can’t, so delays in symptoms don’t mean safety.
What to check in the next two days
Focus on three things: vomiting (especially with bile), stool consistency (sudden diarrhea suggests irritation), and gum color. Press gently on their gums—normal pink should return within two seconds; delayed refill or a pale/yellow tint means trouble. Keep water available but don’t force food if they refuse it—fasting briefly can reduce liver workload.
Unlike a one-time toxic dose, aflatoxin lingers. If your dog shows even mild signs like lethargy or one vomit episode, assume the toxin is active. Their liver might handle it, but waiting to see risks irreversible damage. Small breeds crash faster, but your dog’s size buys only hours, not immunity.
Why you might not see mould but still have risk
Aflatoxin-producing moulds don’t always create visible growth—sometimes they colonize the nut internally during storage. The handful your dog ate could have had a few contaminated nuts mixed in, spreading the toxin. Roasting kills mould but not pre-existing toxins, so appearance isn’t a reliable guide.
Dogs sniff out rancid fats better than mould, so if they willingly ate these, you might assume safety. Wrong. Their attraction to oily smells overrides toxin detection. The real clues come later: if their breath smells unusually sweet or their belly seems tender when touched, those are metabolic red flags.
How this differs from peanut butter scares
Unlike xylitol-laced peanut butter, which causes instant blood sugar crashes, spoiled peanuts work slowly. The danger isn’t choking or a sugar crisis—it’s cells silently suffocating as the liver fails to filter toxins. A 12 kg dog’s liver is roughly the size of your palm; aflatoxin attacks its ability to regenerate.
Emergency vets see more ‘mystery’ liver cases from stale nuts than acute peanut allergies. If your dog had a known peanut allergy, you’d see face swelling or hives within minutes. Here, the threat hides in what the mould left behind, not the nut itself. Store all nuts in sealed containers, not bowls—dogs counter-surf more often than we admit.
The full verdict, portion guidance and serving notes are collected on the Peanuts food facts page.