Yes these are actual dog shirts!! You can find them near the registers and they have collars, leashes, squeeky toys and food/water bowls. Not all Old Navy's have the same selection, but it's worth a shot. I've also seen some of the items on ebay, of course for a lot more than you can buy it at the store
This time the shirt was $5, last month the Valentine shirt was only $2.50, but they are still cheaper than buying ones online.