There's a new product out not sure if you've heard of it, Petzlife Oral care gel which can be used on cats and dogs and you apply it either with finger or soft toothbrush and it breaks down the plaque etc without having to brush. It's applied daily until the teeth are clear then 3-4 days thereafter... I've just started a trial run on my dog at the moment with a view to stocking it
here's the link
PetzLife Products Inc - "Dedicated to Improving Pets Lives