My dog throws up right after eating fast, why

What most fast eaters do is closer to regurgitation, an almost effortless bringing up of undigested food, rather than the more active, abdominal-heaving vomiting that follows an upset stomach. The food often still looks like tube shaped kibble and can appear within minutes of finishing the bowl.

Large gulps of food combined with swallowed air can overfill the esophagus before it has fully relaxed to let food pass through, so it comes straight back up. This is more likely with a very large meal eaten in under a minute or two.

Slowing the meal down with a slow feeder bowl or by splitting it into smaller portions is usually enough to stop this pattern within a few days. If it continues after slowing the pace, or if the dog then eats the regurgitated food and repeats the cycle, it is worth mentioning to a vet.

Some fast eaters bring food back up and immediately eat it again, sometimes repeatedly, which can look alarming but is usually just the same gulping problem compounding itself. Removing the dog from the area briefly after any regurgitation, rather than letting the cycle repeat, along with the same slow feeder and smaller portion strategies, tends to break the pattern within a week or two. Cleaning up any regurgitated food promptly, rather than leaving it accessible, also reduces the chance of a repeat cycle happening while you are not in the room to notice or intervene. Keeping a brief note of how often this happens across a couple of weeks helps show a vet whether the pattern is easing with slower feeding or staying the same.