
Agree with you suejaw re artificial colours and additives.
If you look at children when they get hyperactive the cause are the artificial additives in food, typically in sweets. Most people think it's the sugar that causes the problem, but it's not. (At least per a report on the BBC a couple of days ago.)
I stay away from any dog foods that contain artificial ingredients, it's easy enough to do. Both people and dogs are now bombarded with more artificial ingredients - whether it be in foods, or cleaning products, in the quality of the air we breathe - and the combination of all of these is believed to be behind the sharp increase in asthma and allergies in people. I bet dogs are impacted too.
So if I can avoid artificial colours and additives in my dog's food I do, and it's easy enough to do.