Thank you for adopting! The safest bet is for him to see a veterinarian for a full exam, blood work, etc 1) At one year of age it's not normal for a dog to be lethargic as his daily normal behavior:( 2) Shallow breathing would have me concerned. There's so many things that could be causing him to be extra wiped out after surgery. Hopefully there's nothing serious going on that a few days of pain medication and ongoing good nutrition and your love won't remedy.
#PetHealthandNutrition