I am not the best to answer this because my husband "lets" me do all the taking care of for our dogs. We have 4. But one is his on Paper. He takes her to the vet, feeds her and watches over her. I buy dresses and vest and shirts for mine but I do not buy anything for her because he does not like the idea of putting clothes on a dog.
It really justs sounds like he is a litle jealous. Mine is too but now that he has Trinity he is much better. He still says that if there was reincarnation he would want to come back as a puppy or dog in our home.
Be as patient as you can with him without compromising what you think is best for Pnut. Maybe show him some of your research as to why you made the decision you did about the dog food.
Hope I helped some.