How much should a female dog bleed while in heat?

The amount of bleeding can vary from dog to dog, but generally, a female dog should not bleed excessively while in heat. The bleeding may be light at first, then become heavier for a few days before tapering off again. Some dogs may only bleed for a few days, while others may bleed for up to 10 days. If your dog is bleeding heavily or for a prolonged period, it is important to take her to the vet to rule out any underlying medical conditions.