How do I stop one dog from finishing first and stealing another's food?

The most reliable fix is physical, not behavioral: if the fast eating dog cannot reach the slower dog's bowl, the stealing stops immediately. A closed door or gate between rooms during meals, then letting both dogs out once bowls are empty and picked up, handles this without any training.

A slow feeder bowl with raised ridges or a shallow puzzle feeder can turn a two or three minute meal into ten minutes or more, which narrows the gap between the two dogs and reduces how much idle time the faster eater has near an empty bowl.

Once both dogs are done, pick up bowls promptly rather than leaving an empty one down, since a dog checking an empty bowl can still wander toward a neighbor's bowl that still has food. Feeding on a consistent schedule, rather than free feeding, also makes it easier to supervise this transition every day.

Verbal correction alone rarely stops food stealing in the moment, since a dog that has already reached another bowl is already rewarded by the food in front of it. Preventing access in the first place, rather than intervening after the fact, produces far more consistent results and avoids creating tension around mealtimes for either dog. Keep a written or mental note of each dog's usual finishing time for the first week of any new setup, since spotting a widening gap early makes adjusting the routine much simpler. A slightly larger notebook entry noting weight and behavior together can reveal patterns a quick glance at the bowl alone would miss.