When your dog becomes ill, it can't tell you what it is feeling or where it hurts. Watching what the dog does or doesn't do can indicate if it has an upset stomach. Dyspepsia, the clinical term for a dog's upset stomach, can range from mild to severe.
Vomiting is your dog's way of ridding his system of a substance that didn't agree with him in order to make his stomach feel better. He may have ingested a toy, rock, sock or some other type of foreign object. Or it may be due to a simple case of gastroenteritis.
A dog knows instinctively that eating grass will induce vomiting which will settle his upset stomach. A dog who eats grass will usually vomit soon.
If a dog who lives to eat suddenly shows no interest in eating, this could be a symptom of an upset stomach or stomach ache. Missing one or two meals is not usually cause for alarm, but any more than that could mean a more serious problem.
An active dog who becomes lethargic could have an upset stomach. If a normally active dog becomes unusually sleepy and apathetic, it might have stomach problems.
Bad breath can indicate mild to severe stomach problems. Your dog may only have eaten something that didn't agree with it, but prolonged bad breath could be indicative of an internal disease or parasite upsetting its stomach.
Picking up your dog and hearing it groan, cry out or whimper can be symptoms of an upset stomach. If your dog's midsection is gurgling and tender to the touch, the chances are good it has stomach issues.