A dog, or cat or horse {or any other animal} is nothing like having a child...and if a man says he doesn't want children, believe him.
A dog is a dog - a child is a whole different ball game.
Women ''accidentally'' get pregnant on purpose, hoping the man will change his tune when the baby arrives- to no avail.
So many relationships founder after having children.
There used to be a forum {Searched for it since, but can't find it} about men who hated being fathers - it was eye opening.
They often felt ''trapped'' into having more children than they wanted, or were unwilling fathers to a first child.
A vasectomy is what they need to ensure they don't get 'trapped' in future.
It was full of men complaining how they hated the sound of the baby crying, how the woman told them they were on the pill &c and no need to use a condom..
Any man who doesn't want children needs to buy, keep, and put on his own condom, and to dispose of it safely where the contents can't be ''harvested'' soon after.
There was a case on Radio 4 years ago about a man who was very careful about condoms, but at a court hearing the baby was genetically his- the woman admitted to harvesting the condom contents while the man was in the shower-
He was liable for costs.