This tennis ball is too large to swallow
Brutus, the doberman, has an affinity for tennis balls. He chases them, he hoards them, he lays in the hot south Florida sunshine with them, he shreds them.
And he eats them.
Following thousands of dollars of stomach surgery and two weeks of bed rest, Brutus is a survivor. His owner's wallet is not so fortunate.
Chances are that if a dog can eat a foreign object, he will. Dogs chew, and with that comes the hazard of actually swallowing something dangerous. Stones, clothing (panties in particular), toys, three whole raw chickens (true story) and other objects are dangerous if a dog is out of observation range.
If the object a dog has swallowed cannot cause damage on the way back out, a call to the vet and then induced vomiting may be the best course of action.
The symptoms that a dog has swallowed something that cannot be passed or vomited include listlessness, obvious discomfort, bloating, non-productive vomiting. Don't wait. A dog that may have swallowed something that is causing intestinal blockage should be seen quickly by a vet for x-rays, diagnosis and, in the worst case, surgery.