loss of weight & appetite

Question
My 10 year old neutered male cat has with in the past month started loosing interest in eating & has lost weight from 10 lbs to 8.7 lbs.  I can only get him to eat canned tuna & canned chicken, but no cat food.  I have always feed him meow mix  hairball formula & have just recently switched to the vitality formula for over 7+ cats.  Do you have a suggestion?  Thanks,  Karen

Answer
You said you always fed him meow mix hairball..I wouldn't have changed it. It is 100% nutritionally complete for adult cats. Cats hate change of any kind especially their food and litter..they want the same (in our eyes) "boring" routine life. and if you don't change their food verrrry slowly their stomach will be upset and you will be cleaning up vomit and diarrea. SO..go back to the meow mix hairball and if he does not return to his normal routine
after that, like within the next couple days, I'd take him to the vet for bloodwork..to rule out a developing medical condition.. Thats a lot of weight for a CAT to lose in a month and I wouldn't take any chances especially since he's senior now too.

Thanks for the question