St. Bernards love children. This is a great thing if you have a family or want to have a family and either own or want to purchase a St. Bernard. The dog will bond to your children and will become quite loyal to them. Well-socialized St. Bernards will accept their family's children, and any children that may come to visit or that they may meet in the park or elsewhere. However, as is true with every dog breed, a St. Bernard should never be left alone with a child, no matter how well socialized the dog is.
With any dog breed, it is best to introduce the St. Bernard to a child while the dog is still a puppy. This way the dog will grow up around children and will become accustomed to the loud noises and fast movements that children make. While the St. Bernard is not typically skittish, these things can shock any dog that is not familiar with the behavior of children.
St. Bernards should be introduced to children slowly, perhaps introducing the children one at a time to the dog. This technique depends on what type of personality your St. Bernard has, so work with his temperament. Most often, however, the St. Bernard will happily accept all of your children very quickly.
The St. Bernard is not an aggressive dog. This means that he should not snap or growl at your child even if he or she is near his toys or food dish. What is interesting about the St. Bernard, however, is that the dog will defend a child if he feels the child is in danger or being threatened in some way.
One thing that you must keep in mind is the dog's size. Within his first year, your St. Bernard will grow very quickly. He will reach physical maturity in his first two years, and this growth rate is of course much faster than that of a human child. This means that your child will still be quite small when your puppy has reached his full 150 to 180 pounds. The St. Bernard has to be taught right away that jumping on people and especially on children is unacceptable. Even if he isn't heavy enough to knock over your five year old child when the dog is a puppy, he will be able to knock the child over within a year.
With very small children, the St. Bernard's tail is even a problem. He has a very long and very heavy tail that wags when he is happy, which he usually is. This swishing tail can act like a bat, knocking over anything in its path, and that can include a child. There is no remedy for this except for supervising your child whenever the St. Bernard is around. This is something that must be done whenever a child is with the St. Bernard.