Did your dog take to the kayak pretty quick? Does he ever jump out?
Initially, Nala's only experience with water was our back yard swimming pool, and she was terrified of it. But the first time I took her to the river, she ran right in without a thought. When she's on the river now, she spends half her time in the water and half in my kayak (or canoe), so she does jump out at times when I'd wish she didn't (she doesn't always obey my commands). And she's been known to chase wildlife on the river too, so I generally keep her tethered to my 'yak's anchor trolly, and she ends up pulling me (there's a pic below of her pulling me on the the upper Brazos recently). Lately I've been trying to give her more freedom on the river; just hope she doesn't get into any trouble. Bottom line, she still needs some work, but I find it enjoyable work.
I actually wrote a couple of pieces about her on the river for my blog. LSC: Nala on the Brazos LSC: Nala on the Brazos Part II