This answer is part of Pets Spring Cleaning Campaign. This question is old, but this answer will still help people with the same problem.
Reason for fear:
When an adult dog has a temperament like this to a specific thing (such as children), it is usually because they have had:
- negative exposure;
- or no exposure.
It is pretty common for dogs to have negative exposure to children, especially to young children who don't understand why they shouldn't pull the dog's tail or chase it around.
No exposure is also common, especially in households without children. If as a puppy, your dog never got to interact with children, adding children into the mix for an adult dog may make your dog confused, scared, or angry depending on their personality.
thesprucepets.com says almost the exact same thing:
Why Do Dogs Fear Children?
There are two major reasons why dogs may develop a fear of children.
- A lack of early socialization: Dogs who aren't exposed to children as puppies may become fearful when they meet them later in life. When they encounter children for the first time as adult dogs, they may be extremely frightened by the unfamiliar size, smells, noises, and movements of children.
- The aftermath of a negative experience: Dogs may also develop a fear of children after a painful or unsettling interaction. Young children often have a tendency to pull tails, grab handfuls of fur, steal toys, and even poke eyes. Some dogs are tolerant of children's poking and prodding. Other dogs may develop a fear of children after only one bad experience.
Unfortunately, without enough information in your question, I can't tell you which reason for fear this is, but it is one of the two.
How to improve relations between children and dog?
Will having a baby in the house improve the dog's attitude towards children if he has everyday exposure?
Probably not, as your dog is already five years old, and the best time to expose your dog to new things is when they are a puppy (Source).
That doesn't mean you can't try to get your dog to tolerate children at this age.
Before going to your parents, you should slowly introduce your dog to sounds and scents of children, such as playing crying, and screaming from a speaker.
You, as an adult, can pretend to be a child, and run around and act excited.
Doing things like this will hopefully get your dog adjusted to a child's behavior.
It is also important to give basic training to your dog, teaching things like down (to avoid jumping on children) and stay.
Once your baby arrives, you should slowly and patiently introduce your dog to him. With supervision. Your dog doesn't have to like him, but you must ensure that he will safely tolerate him. Use positive reinforcement for good encounters. Don't force your dog to be with a child, respect his feelings, or else he definitely will dislike children. Take it slow.
are there any steps we can take to minimize the dog's stress with the new pack member arriving?
To ensure the safety of your dog and the child, give your dog a safe space to retreat to if feeling stressed or pressured. Don't let the child near the safe space.
Also, establish ground rules with the children. No teasing, shouting at, grabbing, stepping on, taking from, etc. from your dog.
If you see any unsafe behavior from the children or dog, limit interactions between them to ensure safety for both dog and child.