On occasion y cat has been going back to the litterbox after urinating.His urine output is very good all the time but at times (not all the time ) he will go back into the box and try to go more. He doesnt do this everytime. I took a sample to my vet and the vet said he has crystals in his urine and put him on a urinary diet dry food.She said his PH was 7 and this was borderline.She said the diet with drinking alot should do the job. My question is how do you make a cat drink more water? At times I felt he was drinking to much! My next question is what canned foods are good.He loves canned foods and has been eating Pro Plan canned foods. The vet also advised me to get AZO STANDARD pills in a drug store, when i asked what this is for she said it mask pain he feels , I do not feel comfortable about giving him this, after all its for humans and he does not seem to be in pain, this morning he was normal , playing and jumping and being a bad kitty ! the only signs of anything he shows was like i said AT TIMES he will go back to the box and try to pee more after he has had a normal quanity of urine passed.