If your cat has been on this diet for some years and the problem has just started, I don’t think it could be caused by the food. As cats get older, constipation can become a significant problem but there are lots of other reasons why constipation could develop and it is important to have this problem checked out by a vet. You can also do some simple things which might help – such as making sure the rim of the litter tray is not too high for him to climb over now that he is a bit older. Arthritis is quite common in older cats and not always easy to recognise, so try to rule out whether this could be happening because of a mobility problem by making access to the litter tray easier. I would also supply at least one other additional litter tray in a different location, just in case your cat has been frightened while using the existing one and if therefore reluctant to pass stools there. Equally, if your cat normally toilets outside I would provide an indoor litter tray somewhere safe and secluded. Encouraging activity, if your cat is keen to try it is also a good idea, as generally moving about more can keep the bowel working more efficiently – although be careful not to allow him to over exert himself and strain his joints. Gentle play usually works best. Make sure he is getting plenty of water to drink and again that it is easily accessed.
By Libby Sheridan (Hills Pet Nutrition) (Professional Advisor)