We have a 5 yr old male chihuahua who has recently been losing weight. We brought a female chihuahua who is 8 months old into our household. She just recently got her period. The male chihuahua does nothing but follow her around and does not eat like he once did. Is this normal or is there something that can be done to get his appetite back?

The very first thing to do is to separate them. She is entirely too young to be having a litter. Her body isn't ready for the stresses of pregnancy. Even if he is neutered, he could still mate with her, injure her or infect her. Such carelessness leads to no end of misery. I fine it totally wrong for somebody that isn't even familiar with common terms for a female dog's heat cycle or season, to have an intact female. Do you realize we are slaughtering millions of dogs a year for lack of homes? Do you realize how many hours of freely given time by volunteers it will take to balance it if you careless let them mate? There are people that love dogs and desperately try to find homes for them to keep them from being killed for lack of homes. They would very much appreciate if if you manage to keep her from having one more litter. Better yet, get her spayed as soon afterwards as the vet is willing to do it.

His problem may or may not relate to her condition. I have an extensive discussion on not eating at https://www.askmehelpdesk.com/dogs/information-articles-our-dogs-expert-labman-53153.html#post254171