TIP #1: SPEED EATERS ANONYMOUS
"I feed my two dogs together, and the smaller one seems to gobble her food without chewing it and then throws it back up a few minutes later. Why does she do this?"
She may be worried that if she doesn't wolf down her food, your other dog will get some of it. This is rational fear, but her coping strategy isn't ideal. How about feeding your dogs in separate rooms so the little one feels less pressured by the presence of the bigger dog? If she still eats so fast that she vomits even when she eats in private, then spread out her food over a large surface (such as a cookie sheet) or in several small bowls in different parts of the room so she can't hoover up her entire meal in one breath. And if you now feed your dogs only once a day, divide the food into two or three smaller meals per day instead. Knowing that her next meal is just around the corner may help your gobbler to relax and enjoy her food less anxiously.
If these measures don't work and the vomiting continues, make an appointment with your vet to check for a medical problem.
- excerpted from The Complete Healthy Dog Handbook
TIP #2: ACCEPTABLE RESOURCE GUARDING
Resource guarding is a natural, normal canine behavior. In fact it's a normal behavior for most warm-blooded animals. Even we humans guard our resources - sometimes quite fiercely. Think about it. We lock our doors. Store clerks have loaded .22 rifles under checkout counters, while homeowners keep shotguns and baseball bats leaning in the corner by the back door. Banks keep valuables in vaults. Some of us get insanely jealous if someone pays too much attention to our significant other.
Dogs guard their resources as well, sometimes quite fiercely. This is most troublesome when they guard from humans, but can also get them in hot water when they guard from other dogs. That said, some dog-dog guarding behavior is quite appropriate and acceptable.
As an example: In a dog park or doggie daycare, Dog A is chewing happily on a (insert any valuable resource here). Curious, Dog B approaches. Dog A gives Dog B "the look." Dog B quickly defers, saying "Oh, excuse me!" by calmly turning and walking away. No harm done. Much of the time the dogs' owner isn't even aware that this occurred.
- Whole Dog Journal
Jeff Dentler, CPDT-KA, IAABC-ADT, FFCP, CTDI