Why a 12 kg dog can't handle a full bowl
That bowl likely contained 1-2 cups of milk—far more lactose than your dog's intestines can process at once. Unlike cats where vomiting is the first sign, dogs often absorb some lactose before reacting, which makes their vomiting more concerning. It suggests his stomach is trying to expel what his intestines can't handle, creating a double digestive assault.
The vomiting so soon after drinking means his system recognized the overload quickly. Expect diarrhoea next, possibly explosive and urgent, as the remaining lactose draws water into his colon. Keep him in easy-to-clean areas and have enzyme cleaner ready—lactose-laden diarrhoea leaves stubborn smells that may trigger repeat accidents in the same spot.
The danger timeline for medium dogs
First 4 hours: Vomiting may continue as his stomach tries to empty. Allow access to small ice cubes but no large water amounts yet—swallowing too much could trigger more vomiting. If he can't keep down even ice chips after two hours, vet intervention becomes necessary to prevent dehydration.
4-12 hours: Diarrhoea typically starts during this window. It may be preceded by restlessness, frequent squatting, or whining. Walk him on leash even in fenced yards—lactose-induced diarrhoea often strikes with little warning. Note the stool's consistency: watery is expected, but black or bloody isn't and requires emergency care.
Hydration strategies for vomiting dogs
After the initial vomiting subsides (usually within 6 hours), begin offering tablespoons of water every 15 minutes. If he keeps it down for two hours, increase to quarter-cup amounts. Adding low-sodium chicken broth can encourage drinking, but avoid store-bought broth containing onions or garlic.
Check his hydration by pressing a finger against his gums—color should return within 2 seconds when released. Slow capillary refill time, dry nose, or sunken eyes mean he's already dehydrated. Subcutaneous fluids from your vet may be needed if he refuses water or continues vomiting beyond 8 hours.
When to escalate to the vet
Three vomiting episodes in one hour, or any vomiting after the 8-hour mark, means his system isn't handling the lactose overload. Similarly, if diarrhoea contains blood or resembles raspberry jam, don't wait—these suggest intestinal irritation has progressed beyond simple intolerance.
Watch for bloating signs too: pacing, unsuccessful vomiting attempts, or a tight abdomen. While rare from milk alone, lactose reactions can sometimes trigger pancreatitis in susceptible dogs—shown by severe abdominal pain (reluctance to move, praying position) that demands immediate veterinary assessment.
The full verdict, portion guidance and serving notes are collected on the Milk & dairy food facts page.