• A puppy is lodged in the birth canal and cannot be removed. • There is strong, persistent labor for 30 minutes without delivery of a pup. • There is weak, intermittent labor for 3 hours without delivery of any puppies. • It has been more than 3 hours since the delivery of the last pup, and it is probable that more puppies are still inside. • There is a greenish-black vaginal discharge and no labor or puppies within 3 to 4 hours.