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The most sensible answer to this question is ‘no.’ Yes, letting your female dog have a litter may sound kind and allow her to develop fully, but the reality is that you will potentially attract a whole host of stray dogs who would be very interested in impregnating your prized pet. Females can come in season at the most inappropriate times which can be a huge hassle for you. And let’s not forget, you will then have the challenge of finding new homes for the puppies. Or getting each individual pup micro-chipped, and vet checked as it is mandatory in New South Wales according to the Companion Act 1998. Check with your veterinary clinic as to what their views are. If you are interested in allowing your pet to have puppies, ensure that you are well aware of the associated costs, legalities and headaches that can come along with breeding. 
Why Is This?

The breed of your dog can make a big difference to when she first comes in season. Smaller dogs tend to come into season very early in their lives while larger dogs may take up to 18 months. From 6 months onwards is usual for a dog to come into season, especially smaller breeds of dogs.If you intend to keep your dog ‘whole’, but not breed her, you will have to take good notice of her after she turns 6 months old. Sometimes, dogs can come in season when they are less old, but this is rare and may indicate that there is something wrong with your dog.

Should I Breed Her The First Season She Has?

Again, the answer should be ‘no.’ Although she is showing the typical signs of being in season, it is thought best not to allow her to produce a litter of pups with this first season. The dog is often not fully developed mentally for the changes to her body or the continuous whimpering of her offspring. Some dogs will actually refuse to have anything to do with the pups or attempt to harm them in some way. She may also become aggressive towards her owners in some cases. Keep her away from any male while she is in season and, if you must, aim to get her to her third season before you allow her to conceive.

How Do I Know When My Dog Is In Season?

Her mood may change, and she may become ‘sooky’ towards you, craving more affection than usual. She may move differently. A dog that never carries her tail higher than her backbone may suddenly show everything all the time. She may continually lick her vulva. Often the state of her vulva is the first time you will notice she has changed because it will swell and change into a darker color. Later in the heat cycle, she will produce a small amount of blood several times. The heat will last around 2 to 4 weeks, and she will accept mates during that time. The optimum period though, if you wish to have pups conceived, is between the 10th to the 15th from when she first came in season. Hence checking the procreation state of your dog regularly is recommended.