Living with dogs can be beneficial to kids. But children and dogs are not always going to automatically start off with a wonderful relationship.
If you have a young child and are thinking of having a dog there are a few things you need to consider whether buying a puppy or an adult dog:

Puppies
Puppies require a lot of time, patience, potty training and supervision. Puppies also require socialization in order to become well-adjusted adult dogs.
A puppy may become frightened, or even injured, by a well-meaning, curious child who wants to constantly pick him up, hug him or explore his body by pulling on his tail or ears.

Adult Dogs
Adult dogs require less time and attention once they have adjusted to your family, but you still need to spend time helping your new dog with the transition to his new home.

Start In The Right Way:
Small kids should never be left alone with a dog or puppy without adult supervision!

Let your child sitting down whenever it wants to hold the puppy. For larger dogs, have your child sit in your lap and let the dog approach both of you. This way you can teach your new puppy to treat your child gently.

Children often want to hug dogs around the neck. Your dog may view this as a threatening gesture, and may react with a growl, snap, or bite. You should teach your child to pet your dog from underneath the dogs chin, rather than hugging him over his head. You should also teach your child to avoid staring at your dogs eyes.

Children tend to become sometimes fearful when dogs try to take a treat from their hand. This causes them to jerk their hand away at the last second. Have your child place the treat in an open palm, rather than holding it in his fingers.

Children move very quick and have high-pitched voices. Consequently, your puppy may respond to your childs running by chasing him, nipping at his heels, jumping up at him, or even trying to knock him down.

At the same time, kids have to learn to respect a puppy as a living creature who is not to be teased or purposefully hurt and needs time for itself.