Someone on the board PM'd me not long ago about how I introduced D & K - because I'm too lazy to type it all out again, I'll just copy most of my reply to her:
I didn't do anything special as far as intros go. Dena has always been really good with other dogs, and very easy going in general and somewhat submissive in a "You want to be the boss? Sure, whatever" kind of way, so I wasn't *too* concerned. Not an 'alpha bitch' at all, although she does have her moments now that she's got a bratty little bro to pick on, which he totally deserves....
We had him shipped, and I debated bringing her to the airport with us so they'd meet in the car, but we decided to leave her at home. We brought his shipping crate into the garage pen and set it down and opened the door. She barked at him, he screamed, and then she stuck her head in and sniffed him. After that, they were fine.
I have some pictures of their first meeting, and the days following, so you can see how quickly they became fast friends.
That same day
The next day
Carefully sliding the bone out from under his leg, lol!
Sitting together for treats on day 5
Playing on day 8
Some things I think are important is to make sure each of them get some alone time with you. When he was still not housebroken or trustworthy unsupervised I'd crate him or put him in the garage pen while I made dinner or cleaned house, and kept Dena in the house with me. I took her to daycare twice a week while he was too young to go, and then once he was old enough I took him twice a week for a couple of months, so they each had time away from each other. Tom would take Dena with him in the car when he went somewhere and I would spend time bonding and training Keefer. We'd take her with us when we went out to dinner or to Costco, and he'd stay home alone.
After the first week or two they spent most of their time together when we were at work, except for when one of them was in daycare, so I wanted to think of as many ways to give them each individual attention as I could. Now they are never apart unless they want to be. Sometimes when Tom is home working in the office one or the other one wants to be in the house with him, and the other one asks to go outside, but we never deliberately separate them anymore.
I don't know if you've ever had two dogs at the same time before, but I hadn't, so that was new territory for me. I really struggled with knowing when and if I should intercede, and I probably erred on the side of caution. When Dena was a baby I used to wear my treat bag from the time I came home from work until bedtime, and I did the same thing when we got Keefer. When they started playing really rambunctiously, and LOUDLY, I'd break it up with sits and downs for treats. I'd mark and reward attention and calm behavior. When they blew me off I'd put them both in their crates for a timeout. There is a definite tone you'll hear when one of them goes too far and the other gets pissed, and then it's really clear that it's time to step in, but I wasn't exactly sure what behavior seemed okay now, but might escalate into not okay behavior somewhere down the road when he was bigger, so I never let them pick on each other. Usually if they keep going back for more, everyone is fine - if someone is trying to get away and the other one won't back off, it's "*I'M* the alpha around here" time!
I wasn't prepared for the fearsomeness of their play either. We had this sweet, calm, perfect girl in Dena, and then we got her a little brother to play with and she turned into a completely different dog! Still a good girl, but the two of them will chase each other in circles around the dining room table, dive on each other, bite at each other faces and heads, all accompanied by barks and play growls. If you didn't KNOW it was all in fun, it could freak you out 'cause it sounds pretty scary sometimes!
The intro, interaction, and routine questions are pretty much answered above. As far as the other stuff, I've always fed them side by side and they eat at the same time. I've never had a problem them guarding their food from each other. At first, when Keefer was little, I'd wait in the garage while they ate to make sure that whoever finished first didn't try to steal the other ones food, but now I don't bother. They'll both hold a down with their food bowls on the floor in front of their noses, even if I go in the house to refill their water bowl before releasing them to eat. They usually finish eating around the same time and then lick each other's bowls. The only thing they'll guard is bully sticks. Both of them respect each other enough not to push it, so it's never escalated to a fight - if someone gets too close a little growl backs them off immediately. I figure they deserve to chew their evening treat in peace, so I allow it.
We have the garage pen for during the day, so they are together when we're not home. Tom is a general contractor with a home office, so he's around a lot or in and out during the day, so the dogs are wherever they want to be then, either with him in the house, or outside in the garage or their dog run, which is accessible by a dog door from the garage. At night they are crated side by side in our bedroom.
My main worries were about the additional time involved, and having never had two dogs at the same time before, if I would be up to managing their interactions to prevent future problems. I stressed about that a lot - I just didn't know if I'd be able to tell play from something more, and what behavior I should allow and what I should stop immediately. I wouldn't say that looking back that was a silly concern, but it was easier to tell when it was time to step in than I thought it might be. Lots and lots of mutual NILIF helps a lot.
The thing that surprised me the most was how much more assertive and bitchy Dena can be! She's always been the good girl, the calm, well behaved dog, just hanging out and relaxing around the house. She has way more energy now that she has someone to play with. She always seemed perfectly content being an only dog, but I think she really enjoys having another dog in the house, and he definitely does not push her around! She'll stand over him dangling a toy on his head to get him to play, and they love to rip toys out of each others mouths and playing tug. It's a lot of fun, and very entertaining, and in many ways it was much easier than I expected. They got along really well from the very beginning - he's always been bold and confident, he loved Dena and was never intimidated by her, and she was totally fascinated with him. The hardest part was just having a new puppy and all that goes along with that.