Rosie who is 10 has had to have hers emptied twice in the last 4 months, never having had a problem before. We switched to raw feeding just over 12 months ago and her poo has become much smaller on this diet, which is normal. My vet feels that because her poo is not now as bulky as before, she is not now forcing the anal glands to empty. I have now started to give quinoa, which is non cereal, and blitzed veg, to her food. So far so good.
I'm not going to change from feeding her raw as I feel she has done so well on it and the most important, she loves it. Strangely the amount of bone doesn't seem to be a factor, just the size of the poo. If it becomes too chalky or hard I just adjust the amount of bone in the next few meals.