Hello, my name isXXXXX and I have over 20 years of experience as a veterinarian. I am sorry to hear about Dip's habitof licking things. Is this a new habit for your older fellow?Ideally Dips would see his veterinarian for an examination and some blood tests including a complete blood count, biochemistry profile and feline leukemia and feline immunodeficiency tests. Some cats exhibit pica (eating or licking non-food items) when they are anemic or sick and we do want to make sure that he is healthy and there is not a physical reason for his behavior. If you have other cats in your home and they seem normal an infectious cause is less likely, though some cats can carry immunosuppressive viruses and appear healthy.
Sometimes in older cats licking non food items can be a sign of senility and anxiety. If he if physically normal it may help to use medications to reduce anxiety and improve brain function, for example selegilene (Anipryl).In case this is related to nausea at home to try and settle his stomach you can give either: 1)Pepcid ac (famotidine) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 12 hoursOR2)Prilosec (omeprazole) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 24 hoursThese are acid reducers and should help him feel better.
I also recommend feeding soft foods mixed with water to make eating and swallowing more comfortable. Sometimes cats lick things because they have mouth pain too.
If he is refusing to eat even soft foods you can try offering meat baby foods or a bland diet of 2/3 boiled, shredded white chicken and 1/3 boiled white rice. You can mix in low salt chicken broth or warm water to make the food softer and easier to eat and swallow as well as get more fluids into him.If he isn't eating his food well he should see his veterinarian for diagnostic testing, intravenous fluids and supportive care. Cats that don’t eat for several days can develop a type of liver disease (hepatic lipidosis) because as they break down fats for energy to live the liver becomes overwhelmed, so we do want to keep a close eye on him.Please let me know if you have any further questions.