What happens after a female dog gets neutered? Any specific issue that she can face? Also how do they get neutered? By any tablet or any surgery?

Neutering has many advantages like the pet wonot face any uterine issues like pyometra and others in the senile stage and pet may gain weight after the surgery so have to look into that part, the pet wonot face any issues after the neutering and it is done by surgery but not by any tablet