Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to know when a dog is done giving birth [title] Consult your vet to see how many puppies should be in the litter. [step] Usually, the vet will examine the dog around day 50 of pregnancy to see how many puppies it is carrying. This number should tell you how many puppies to expect.

Ending1: [substeps] Puppies younger than 39.5 weeks are considered very young. [title] Perform a pre-delivery test on your puppy. Ending2: You can also identify when puppies are scheduled to be born. [substeps] Puppies are usually not weaned when they are between the ages of two to six weeks old. Ending3: [title] Ask about vaccinations when the dog is ready to give birth. [step] This information will help you decide on the best course of action. Ending4: If the dog hasn't had all of the puppies yet, there are more to come. [substeps] It is extremely important to take your dog to the vet throughout pregnancy.

Answer format: ending1/ending2/ending3/ending4