How overnight hazelnuts differ from fresh ones for a 6 kg dog
Hazelnuts exposed to moisture (from humidity or saliva) for over 4 hours begin growing invisible mold colonies — your Shih Tzu essentially ate two problems: the nuts themselves and whatever microorganisms thrived on them. The vomiting suggests his system recognized the double threat and is trying to expel it, which is actually preferable to silent absorption of mycotoxins.
Small breeds process toxins differently than larger dogs — what might give a Labrador mild indigestion can overwhelm a Shih Tzu's detox capacity. His current diarrhea indicates the body's emergency purge protocol is active, but watch for a dangerous shift to lethargy or wobbly movements, which would signal toxin penetration beyond the gut.
The mold danger hiding in seemingly normal nuts
Not all mold is visible — the most dangerous mycotoxins come from microscopic growth between the nutmeat folds. These toxins attack the nervous system first, often causing subtle tremors in the lips or eyelids before full-body shaking begins. Your dog's small mass means neurotoxins circulate faster and concentrate more intensely in his tissues.
Fatigue after vomiting is normal, but pay attention to his recovery pace. If he remains listless between vomiting bouts or shows disorientation (like bumping into walls), this suggests mycotoxin absorption. The high fat content also risks triggering pancreatitis in small breeds, especially when combined with the gut irritation from mold — a vicious cycle of inflammation.
Why you can't wait out vomiting in this case
Most food-related vomiting resolves in 6-8 hours, but mold toxins change the equation. Continued diarrhea beyond that window risks dangerous dehydration in a 6 kg dog — his fluid reserves are about 1/10th those of a 60 lb dog. Check his gums: if they feel tacky rather than slick, or if the skin on his neck doesn't snap back quickly when pinched, he's already dehydrating.
Blood in vomit or stool (appearing as coffee grounds or red streaks) indicates gut lining damage from either mechanical irritation or toxin effects. Small dogs have less intestinal surface area to spare — what would be a minor lesion in a larger animal becomes a significant injury at his size. Rapid breathing when resting is another red flag, suggesting toxin-induced metabolic acidosis.
When to bypass monitoring and go straight to emergency care
Three specific neurological signs demand immediate vet attention: uncontrolled drooling (not panting), pupils of unequal size, or inability to stand without swaying. Mycotoxins can cause these symptoms within 2-12 hours of ingestion in small dogs. Don't attempt home remedies — some well-meaning suggestions like activated charcoal can be dangerous if vomiting persists.
If his vomiting stops but he develops a sudden interest in shadows or invisible objects (snapping at air), this indicates hallucinogenic mycotoxin effects. Your vet may need to administer intravenous lipid therapy — a treatment that literally pulls fat-soluble toxins out of circulation. The sooner this begins, the better his prognosis for full recovery without lasting liver impact.
The full verdict, portion guidance and serving notes are collected on the Hazelnuts food facts page.