How to use EEG on dogs? I need to take EEG readings on dogs for BCI and seizure prediction research. To do so do I need special equipment? 

Is there an accepted approach in terms of frequency, electrode size and placement, etc?
After a quick google search I (surprisingly) found that it already has an application: the No More Woof headset. 

I believe the most important part is that you have a headset that fits and does not move when a dog walks or turns his head. Then it does not matter that much where and how the electrodes are oriented. The only thing you need to do is map the locations of the available electrodes to correct brain-regions of a dog. For human studies there are many different layouts of EEG caps (FieldTrip), which is fine, because they have such a clear mapping to brain areas. 

How a dog's brain looks like and what frequencies can be expected I do not know, however. Perhaps you can follow up on the "No More Woof" to see what references they used to base their approach on.