✔ 最佳答案
That is between you and your vet. An exam may reveal why he is crying at nite and loosing interest in food.. It may be treatable, it may not be. Being that he is 16 and also blind, deaf and senile, you may decide its not worth treating either.
There is no right or wrong decision... I would advise that if you do not euthanize at this time, to at least discuss comfort care with your vet.