How much did your 4 kg dog actually swallow?
Chewing through a bag suggests more mess than ingestion, but don't assume the best. Check for shredded pieces on the floor and estimate what's unaccounted for — a tablespoon of chopped green onions is high risk for a dog this size. The white bulb portions contain the highest toxin concentration, so note if those were in the mix.
Dogs often gulp when startled, so even if you see debris, your pet may have swallowed the worst bits quickly. Watch for green stains around its mouth or onion breath, which confirm contact. Time matters less than quantity here — whether it happened 10 minutes or an hour ago, the priority is calculating exposure.
Small dog, big blood cell problem
At 4 kg, your dog's red blood cells are vulnerable to oxidative damage from even mild onion exposure. Unlike one-time large doses that cause obvious poisoning, repeated small exposures (like nibbling kitchen scraps) can silently accumulate. This incident might be the tipping point if your dog has stolen oniony foods before.
The danger isn't immediate vomiting — it's the slow breakdown of hemoglobin over 24-72 hours. Your dog might seem tired tomorrow but bounce back, then crash on day three when oxygen transport fails. That's why vets run baseline blood tests immediately, then repeat them to catch the downward trend before symptoms appear.
Kitchen first aid while waiting for the vet
Rinse your dog's mouth gently with water to remove onion residue from gums and teeth. Don't use soap or hydrogen peroxide — irritation could worsen nausea. Offer ice cubes to lick rather than a full water bowl; this prevents gulping that might trigger vomiting while keeping hydration up.
If the vet advises home monitoring, set up a quiet space with easy access to go outside. Crate rest is better than free roaming right now — excitement increases circulation, spreading toxins faster. Have a flashlight ready to check gum color (they should be bubblegum pink, not pale or yellowish) every few hours.
Why this isn't like other food scares
Many owners mistake green onions for 'mild' compared to regular onions, but the toxicity per gram is similar. What changes is the form — pre-chopped supermarket onions often have more surface area exposed, releasing toxins quicker in the gut. Your dog's small size turns what would be a non-issue for a Labrador into a hematologic emergency.
Watch for subtle behavioral clues in the next 8 hours: refusing favorite treats, sleeping more than usual, or panting without exercise. These precede the dramatic signs like collapse or red urine. Keep other pets away — stressed dogs may hide symptoms, and you need to observe every small change.
The full verdict, portion guidance and serving notes are collected on the Green onions (scallions) food facts page.