Normally, the dogs achieve sexual maturity at the age of 6-12 months. However, some large breeds have their first estrous cycle at the age of 12-24 months. There are four stages of estrous cycle in dogs such as proestrus stage, estrus stage, diestrus stage and anestrus stage. During the estrous stage, the female dog allows the male dog to mate. If the eggs are fertilized by the sperms from the male dog, then the female dog gets pregnant and an embryo is formed. You should consult the veterinarian to confirm the dog's pregnancy. Generally, normal gestation period in dogs is approximately 58-68 days, with an average period of 63 days. There are certain conditions that can confuse with pregnancy such as mammary gland neoplasia (cancer), pyometra (infection of the uterus), mastitis (inflammation of mammary glands), false pregnancy, or abdominal enlargement due to fluid accumulation or organ enlargement.

There are certain signs and symptoms, from which you know about dog pregnancy. Knowing the symptoms, you will be able to take care of your dog. For the first three weeks of dog's pregnancy, you might not notice any symptoms. The pregnancy symptoms can be divided into different stages. Here are some symptoms of pregnant dog:

Early Signs

Reduced appetite is one of the earliest signs of a dog's pregnancy. The dog feels exhaust easily and becomes less active during gestation. It happens because there are certain changes in the hormonal levels to support the process of embryo production. Growth of nipples is another good indication of dog pregnancy. The nipples of unbred female dog are quite small and the area beneath them is flat. Once the pregnancy is in progress, the breast material is developed beneath the nipples to prepare for eventual milk production. You can also notice some behavioral changes in most female dogs during the pregnancy period. They either show affectionate behavior or desire to be left alone.

Progressing Signs

After one month of pregnancy, the dog shows some progressive signs. You will notice an increase in appetite and decrease after ending the heat period. There is a remarkable weight gain and the dog's abdomen becomes thick. If you gently check the abdomen, you will find it firm and thick.

Late-term Signs

The signs of pregnancy increase remarkably in the last weeks of pregnancy. There is a significant increase in abdomen size. It becomes firm and hard. If the dog carries only one or two pups, then the abdomen is slightly increased, but it is firmer. Smaller breeds generally show more abdomen size as they have small space to hold the puppies. The abdomen of some small breeds literally drags the ground at the end of pregnancy period.

You can notice movement of the puppies during last weeks of gestation. A few days before delivery, there is a definite increase in their movements, as they get into position for birth. Milk production starts and colostrums, the first milk, may leak as the time of delivery comes near. You will notice the nesting behavior of female dog. She will prepare the area where she wishes to deliver the pups.

Knowing these symptoms, you can take a good care of your pregnant dog. You need to feed a special, nutritional diet for healthy mother and puppies.