An 18 years old cat,... Anything out of the ordinary had to be checked. Can be so many things and in an old animal, you don't want to take a chance

Yes it is , through grooming[ saliva], scratching, sharing food bowls and cat litter. BUT  having said that, I do know of a cat who was rescued from the pound and lived merrily with another 7 cats for a couple of years before they realised he had feline leukemia. None of the other cats ever got … Read more

Take him to the vet asap. Could be poisoning,gastric ulcer, lots of things!