My pup is now about 6 months old. He is just about done teething, most of his new teeth are in. But in the past few days his personality has changed drastically. He went from being a little monster, running around and playing all day, prey drive through the roof...also, when I'd turn on the vaccuum or hair dryer he'd go crazy barking and running at it. Now, all of a sudden he's totally changed. He just sleeps all day, doesn't really play at all anymore, ball drive has diminished but he'll still chase it around, just not as much as he did or with the same focus.
He's from strong working lines, with two VERY drivey parents, and had tons of prey drive until recently. He just seems so listless now...he was driving me up the wall he had so much energy before, but now he just sleeps.
Can I expect him to get his drive back again, or is this permanent? Anything I can do to help? I have been doing work with the ball on a string since I got him at 9 weeks, basically how Ed's article describes, I was thrilled with how he was coming along. He'll still chase the ball but not with the same energy. If this is normal, when can I expect that aweosme drive to return?

He sounds sick to me. What did the vet say?

My 2 cents. How is his diet? and Also when you are training, are you allowing him to win enough. I had a problem with my dog as I was not rewarding enough........therefore the dog sees it as "whats the point". Ed covers this in his tapes that a dog with low drive needs reward more often. Im just wondering if in your training, that your not rewarding enough, so therefore the dog is giving up which looks like low drive to you.

The diet is fine, no changes made since I got him. His coat is shiny, he's the picture of a healthy puppy. No symptoms of any kind, except a change in personality.

I haven't been doing quite as much work with the ball since he's been teething, but his drive didn't change at all until very recently. I'll take him outside again today and see where he's at, it's been raining a lot lately so he hasn't gotten to go out and play as much. But I expected him to be going stir crazy, and that i'd have to take him out in the rain (which he's not a big fan of either!), but he's just turned into an angel. And this did start before it started to rain, so I don't see the rain having anything to do with it.
I'm just freaked out...I was expecting him to get more wild as he grows and he's turned into the model puppy. Maybe this will pass...

Did you vaccinate recently? To just get low like that all of a sudden is not a good sign. I would without hesitation take him to a vet for a check. Maybe he ingested something he shouldn't have. Good Luck.