I'd say you need two things to really make these step up the scale;
First you need to get your flight light higher otherwise you're going to keep getting those demonic dogs coming right at you with their glaring red eyes! If you're using the popup flash its not going to work; if you're using a speedlite flash get a flash bracket (loads on ebay, though some are better than others) and an offcamera flash cord and raise the flash up higher.
Secondly (and I don't know what lens you're using, you might need one with a wider max aperture) I find the fence in the background distracting - especially so since these are pet photos not captive animal zoo shots. I think that, difficult to focus as it will become (because you'll have a much smaller depth of field) using a much wider aperture would help a lot in dropping the depth of field off and giving a natural blur to the background. You might also (depending on the size and shape of the enclosure) shift your shooting direction so that there is more distance between the dogs and the fence background.