Cat Health Questions? Ask a Cat Vet for Answers ASAP.
Older cans can lose their voice. This happens to both inside and outside cats. The problem may be temporary if it is due to a reaction to something in the environment that he is mildly allergic to.
The problem may permanent if it is due to weak muscles and nerves in the vocal cords.
Keep an eye on him. As long as he is able to swallow when he eats and drinks he should be fine