My beautiful, 14 year old Tonkinese, "Wednesday Blue," has had a constipation problem for at least a year or more. She will attempt to poop in the litter box but she is too bound up and ends up dropping it somewhere else in the house. Without getting any more graphic than necessary, here poop is always hard and dry. The vet put her on Royal Canin Fiber Response and there may have been a very slight improvement but nothing close to normal. The vet has no other ideas except to keep selling me this prescription food. I was wondering if perhaps I should feed her canned food which would put more water in her diet. The problem, however, is the weekends when I'm not home. Normally I just leave a full bowl of dry food but that won't work with canned. So my question is this: Can I feed her canned food during the week and the dry food on the weekend? Any suggestions or comments would be greatly appreciated.