Gestation, or the term of a pregnancy in dogs starts from the first time they are bred, or fertilised, and lasts until the puppies are born. This period can vary based on the breed or size of the dog, but usually is about 9 weeks. Unlike humans, female dogs can have menstruation cycles throughout their entire lives, and can have puppies at any age after their first heat.

Puberty begins in a female dog from between 6 to 24 months of age. She mates when she is in heat, or oestrus. There are four stages of the oestrus cycle:

*Proestrus Stage: This is the preheat period, lasting 4 to 9 days.

*Oestrus Stage: This is the stage when the female dog will mate, and lasts 4 to 13 days.

*Diestrus Stage: Lasting 2-3 months, this stage involves the pregnancy, elevated progesterone levels, and swelling of the mammary glands.

*Anestrus Stage: This is the longest lasting stage, about 5 months, when the female dog starts to prepare for the subsequent heat cycle.

It is usually hard to predict if your dog is pregnant or not, even if conception was 5 weeks prior. There is not a standard pregnancy test for a dog's urine or blood that can be done at home. It's generally advised to take your dog to the vet to confirm a pregnancy. A pregnancy is usually detected by X-ray 45 days or so after fertilisation.

Noticing Signs of Pregnancy in Dogs

Early Signs

*Decrease in appetite is often one of the first symptoms you may see in your dog. She may have morning sickness and begin eating less in the first few weeks of becoming pregnant.

*Your dog may feel exhausted, and may show a sudden decrease in activities as she experiences hormonal changes.

*Your dog's nipples may enlarge and may be a sign of pregnancy progression. Breast material will begin to develop under the nipples, which will eventually increase to prepare for milk production.

Mid-term Signs

*Two to three weeks after gestation, your dog may show an increase in her appetite.

*Her nipples may become swollen and darken in colour.

*Your dog may begin to gain weight and her abdomen may become thicker, which can be seen about four weeks into the gestation period.

Late Term Signs

*There will be definite, noticeable growth in the abdomen, which will vary based on breed, size, and how big the litter is she's carrying.

*You will begin seeing and feeling the puppies move during the last stage of pregnancy.

*White fluid may begin coming out of her nipples, signalling she is ready for lactation.

Behaviour and the Gestational Period

Just as in humans, a female dog may show changes in her behaviour while she's pregnant. The farther the pregnancy progresses, the more these changes may be seen. She may become restless, anxious, and may want to be left alone or go to an isolated area. With the growing belly, she will become uncomfortable, and may become aggressive. You should not let children play with a pregnant female dog as she may lash out at them. It is also not unheard of for a pregnant dog to tear clothes, papers, or drapes trying to make a "nest" to give birth in.