Well when he had the bout of it in Texas he had flecks of blood in his vomit and the vet said it was colitis brought on y the stress of the trip. If it affects only the colon then I wonder why they vomit at all then.
Ok maybe from this...Bleeding can also be caused by eating the wrong foods. Pets that raid the trash or root around in the compost pile may suffer from food poisoning and get miserably nauseated.
Their retching can break blood vessels in the esophagus, the tube that carries food from the mouth to the stomach. This isn't a serious problem, but it will cause the vomit to look a little bloody.
One of the most serious -- and all-too-