Oh, then this is the fact i must say
Good to know that you can notice the behavioral difference in your cat. In most of my case, I just couldn't notice it.. They act strangely normal, then just vanish out of the thin air.. yes, they are all roamed free, not a 100% indoor cat..
I once went to a vet and she explained that cats have great antibody/resistance against sick/fever.. In a case you see them unwell, then surely it is truly sick - which is more than the fever we always have.. i must say demam panas instead of demam biasa.. because cat will act like normal if they are demam, as in nature, they will have to feed themselves or their family no matter demam or tak..