I have a 10 week old black lab. When we first got him, he did not mind when we picked him up and was great. Now, recently within the past 2 weeks, he pees every time we pick him up. I know a lot of people will say its because he's excited, but even when he is with us for a while, he still pees when we pick him up. We take him out regularly and take him out right after he eats or drinks. Why is he all of a sudden doing this when he wasn't doing it before and is there anything we can do to prevent it?

Has something happened?

Did you yell at him or hit him when he peed or did something you didn't like?

This sounds like fear. He's worried that you'll get mad, and it's causing him to pee when you pick him up.

How are you training him? What methods are you using?

No we don't hit him or anything along those lines. The only thing we do when he does something wrong is say "no"

Has something scared him while he was outside? Anything at all that made him fearful?

This really sounds like a fear reaction.

The best way to proceed would be to make sure you take him outside for a pee before picking him up. When he does pee praise him as if he's just won a gold medal in the olympics. Lost of "good boys" and a treat. Make sure he knows that this is what you want him to do.

If he pees when you pick him up, take him directly outside, give your pee command, and wait for him to do his thing. Praise, praise, praise.

Don't scold when he pees on you. Ignore it, don't react in any way.

Once he stops getting a reaction then hopefully he'll clue into the fact that peeing on you isn't going to get him anywhere.

In the meantime, any other household accidents should be corrected as usual. A firm no, then directly outside to do his thing. Remember the praise. The praise is very important.

He's still very young. A lot can happen at his age that can scare him into nervous peeing. Our lab was around 12 weeks old when our neighbor redid his roof. Our pup went out front to sniff around, and the roofers dropped some old shingles off the roof. It made a very loud sound. Our puppy was terrified, and for many months after that he'd pee out of fear. It took a while, a lot of patience, a lot of praise for the right behavior, and not reacting to the nervous peeing, and then he finally stopped. :)

As I am a vet I have had a lot of customers with there dogs saying he/she wees when he/she picks it up!
Mostly when an animal does this it means it has been scared by something/where it is nothing really to worry about what you have to do is if he/she does something good you praise him/her carry on doing that and your dog will understand there is nothing to be scared of but keep doing that every time and this won't happen again hopefully.
Hope it works for you! :-)