I'm editing some wording and details in the original message and my response for the sake of anonymity and clarity, but this and all the Reader Question articles will be based on real people's questions and the real answers I gave them. So, without further ado, the first Reader Question!
Is it unusual for a puppy to have two distinct personalities during the day?
He is sweet as can be from rising until about 2. Then he starts to get wound up and is a total maniac by 5 until bedtime. Leaping, biting, not listening. We've tried walks, rousing play, fetch, field trips, just about everything we can think of. The only thing that pacifies him is constantly feeding him a kong. I'm about ready to call it quits.
Getting Too Old For This
What you describe is really normal, and it's a stage that lots of puppies go through. Some puppies just pass out when they get overtired, but some become horrible devil monsters instead. I've had some of both in my own dogs. It's so common for pups to get confused, bratty, and wound up at exactly that time of day, so it's not caused by anything you're doing wrong. It's like a toddler who melts down with a massive tantrum because it's bedtime, but he also can't keep his eyes open.
Tuckering him out and training his brain earlier in the day can sometimes shorten the duration of the crazy behavior later because he won't have the physical and mental energy to sustain it, but that doesn't always work to eliminate it entirely. So start with being sure you have ample training, problem solving, and physical exercise earlier in the day when he's more manageable.
When he's still being bratty after 5, the crate is your friend. So is lowering your training expectations for that time. Work on the complicated stuff earlier in the day and plan on that 5-to-bedtime slot for just managing him and carefully nonrewarding the insane behavior and rewarding any good behavior you get. You can also give yourself a break by putting him in the crate with his kong when it's just too frustrating. You should always try to get at least a little bit of a positive interaction from him if you have the energy, rather than just putting him away when he's crazy, but don't feel like you have to fight your way through every single minute of this time slot every single day.
What I would not do is any kind of collar or verbal corrections when he's being a nut job like this. I wouldn't in general, but this would be a particularly bad time for them. He's already got too much energy and a thoroughly confused puppy brain. Anything energetic or interactive will probably just ratchet up the behavior, so withdrawing your attention and nonrewarding him will show him that being bratty makes humans super boring. Also, be sure that if you do crate and kong him, don't do it right after he does something like bark or nip. There's a chance he'll find it really rewarding to go into his crate with a yummy kong, so you don't want to teach him that he can have that if he's a brat.
It'll take a bunch of repetition because he's worked himself into such a tizzy, so you probably won't see much improvement in the first week, but he should learn and also mature his way out of this relatively quickly.
Keep up the good work!