Listless dog

Question
I have a 11 month old Jug (1/2Jack Russel, 1/2 Pug).  Usually he is active and jumps on anyone who comes through the door.  Since Sat, however, hes been very listless.  Hes always shivering.  I noticed on Friday his testicles looked extreamly swollen, but today they look normal again.  I have no idea what is wrong with my dog and hes acting so sad and cold.  Could you please help me.

Answer
These are the kind of dogs that usually pull a muscle or strain something doing just what you described- jumping on everyone.

Anytime a dog shivers and acts sad it's usually because they are in pain. I can't tell you from what, but I can tell you that he needs to see a vet and after he is well he needs to be neutered also.

You will have a healthier happier dog once he is neutered and you will prevent him from having many, many health issues from not being neutered.

So get him in to see the vet so he can find the source of this pain and be sure to mention the swollen testicles.
He is more than old enough to have the surgery.
I hope he is well soon.