How long after labor starts is a dog considered to have dystocia?

A dog generally gives birth about two hours after its water breaks. If the water has broken and the dog shows clear straining but still has not delivered after two hours, it is very likely dystocia, and the owner should take it to a vet or contact a vet promptly. Dystocia is dangerous; if a dead fetus forms in the womb it can cause septicemia and death. A smooth delivery may finish in about half an hour, while a slow one can take 2-3 hours; whenever signs of dystocia appear, help the dog as soon as possible.