lethargic, not eating properly

Question
I own a 5 and 1/2 year old Boxer. Always very enthusiastic and happy. The last 3 days he doesn't seem to have much of an appetite. He will eventually eat but has always had a very strong appetite. He seems a little lethargic and doesn't quite seem to have his normal energy level. Any thoughts? How long should I wait before I make an appointment with his vet?

Answer
Walter,

I don't know where you live, but could it have anything to do with the heat?   Is he drinking water,  normally or in excess?  Also, does he eat at all?  Or just a little ?
Is he having normal bowel movements, or is it diarreah? Any vomiting ?

If he is not eating at all more than two days, then I would take him to the vet.  If he is extremely lethargic ...won't get up or won't walk, then I would take him to the vet,  or if he has diarrhea and/or vomiting , I would take him to the vet.

If he is just not acting quite "up to snuff" , then I would give it a few days and see if he gets better.  If there is no improvement in a few days, then I would take him in.  If a normally active dog becomes lethargic for no reason,  then something is wrong.   I hope this has helped!

God Bless,
Becky