The end of innocence?

Zack turned 19 months yesterday and we've now had our first time-out. He's been running around like a crazy boy having fun, but, he's just as likely to run away from us as run toward us. The problem has been developing around Zack's treatment of Tobey. He's been occasionally hitting him with toys and just started kicking the dog. He is throwing and kicking a ball well, it is just that those actions are translating to the dog. What doesn't help is that if Zack makes Tobey squeal in pain, he laughs because it is a funny sound. Tobey has been very forgiving in all of this which is fortunate. However, we've started to take time-outs with him when he doesn't listen to us. The challenge there is trying to keep a toddler still for 30-60 seconds. That is just as hard.