Lineup line art

So a while back a coworker of my mom's asked if I would do up another picture like this except using adult dogs and tennis balls instead of puppies and leashes. I think perhaps she wanted huskies again, but this is what I got. They are rather cute, though, aren't they?

I sketched this out some time ago during a lull at work, but didn't get around to inking it until this afternoon. I liked the line art and figured other people might as well, so here you go! Feel free to color this if you want (no need to ask permission to do so!); just please remember to credit me if you do. I should have my own version up fairly soon. ^^

Note: This is Photoshop compatible (just duplicate it and set the new layer to "multiply") but not for MS Paint or anything like that. Sorry.