Why mould matters more than the basil itself
A few wilted basil leaves won’t harm your 15 kg dog—it’s the mould growing on them that could cause trouble. While fresh basil is harmless, mould produces toxins that may irritate his stomach or intestines. Since he ate only a small amount, severe poisoning is unlikely, but digestive upset is possible within the next day.
Watch for signs like repeated vomiting, diarrhea that lasts more than a few hours, or refusing food he normally loves. These suggest his system is reacting to the mould. If he acts lethargic or has tremors, call your vet immediately—those are rare but serious signals.
How to handle the next 12 hours
Don’t panic if he vomits once or has a single loose stool—his body may just be clearing the irritant. Offer small amounts of water frequently to prevent dehydration, but hold off on food for 6-8 hours to let his stomach settle. If he keeps water down, try a bland meal like plain boiled rice with a bit of lean chicken.
Skip his next regular meal if he seems queasy, but don’t fast him longer than 12 hours unless your vet advises it. For a dog his size, this tiny amount of mould likely won’t cause lasting harm, but monitoring him closely ensures you catch any unusual reactions early.
When compost risks go beyond basil
Compost piles often contain other mouldy food scraps or even toxic items like onions or chocolate residue. If your dog raids the compost regularly, consider fencing it off. A one-time nibble of mouldy basil is low-risk, but habitual compost diving exposes him to greater dangers.
Check the area where he found the leaves—if he may have eaten other decaying plants or rotting fruit, the risk increases. Mushrooms growing near the compost are especially hazardous. For this incident though, focus on the basil mould alone unless you spot evidence he ate something else.
Why bigger dogs handle mould better
Your 15 kg dog’s size works in his favor—the same few mouldy leaves would pose a higher risk to a tiny 2 kg chihuahua. Larger bodies dilute toxins more effectively, so his reaction will likely be milder. Still, monitor him as diligently as you would a smaller pet, since some moulds produce potent toxins.
If he’s otherwise healthy with no liver or immune issues, he’ll probably process this without trouble. Older dogs or those with pre-existing conditions may struggle more, but for your average adult dog, this is more of a wait-and-watch scenario than an emergency.
The full verdict, portion guidance and serving notes are collected on the Basil food facts page.