The first six hours with a vomiting 5 kg dog
A spoonful of mayonnaise might not sound like much, but for a 5 kg dog, that’s a concentrated fat hit. His vomiting is his body’s way of rejecting what it can’t handle right now. Withhold food for the next four to six hours to let his stomach settle, but offer ice cubes or small licks of water every 15 minutes. If he vomits water three times in a row, stop liquids and call your vet.
Track the timing: vomiting that starts within two hours of eating the mayonnaise suggests simple stomach irritation. If it begins after four hours or includes yellow bile, his small intestine might be reacting too. Note whether the vomit contains undigested food or just frothy liquid—this helps your vet assess how far the irritation has spread.
Why small dogs react more to fatty foods
Your dog’s 5 kg body has less room to buffer rich foods compared to a larger breed. The fat in mayonnaise slows stomach emptying, which can trigger nausea and reverse gut movements (hence the vomiting). Even after he stops throwing up, he might drool excessively or lick surfaces constantly—signs his stomach still feels off.
Watch his posture: a dog with ongoing gut discomfort often stands with his back arched or lies in a tight crouch. His belly may gurgle loudly. These symptoms usually peak within eight hours post-ingestion. If they persist beyond twelve hours or he refuses to move from his spot, the fat load may be overwhelming his system.
Transitioning back to food after vomiting stops
Once he’s kept water down for two hours, introduce a teaspoon of plain boiled chicken or low-fat cottage cheese. Wait thirty minutes—if no vomiting occurs, give another teaspoon every hour for four hours. The goal is to stimulate his gut gently without restarting the nausea cycle. Avoid rice unless he tends toward diarrhea; some dogs get constipated after vomiting episodes.
For the next three days, divide his meals into four smaller portions instead of two large ones. Add a tablespoon of warm water to each meal to aid digestion. Skip treats entirely until his stool returns to normal—usually within 48 hours. If he normally eats a high-fat kibble, ask your vet about temporarily switching to a gastrointestinal formula.
Red flags in the 24-hour window
While most small dogs recover within a day, repeated vomiting can lead to dehydration quickly. Check his gums: they should be slick and pink, not tacky or pale. Press a finger gently on them—the white spot should refill with color within two seconds. If his eyelids look sunken or his nose is dry and cracked, he’s losing too much fluid.
One episode of diarrhea is normal as his system clears the fat, but more than three watery stools in eight hours risks electrolyte imbalance. Similarly, vomiting that changes from food to clear liquid, then to yellow bile, then to white foam shows his stomach is emptying too far—time for veterinary intervention. Don’t wait for all symptoms to align; one worsening sign is enough to call.
The full verdict, portion guidance and serving notes are collected on the Mayonnaise food facts page.