Visiting the veterinarian means that you need to make the time to go with sufficient disposition to be able to talk with the doctor without any rush.  There are times and indeed there are some doctors that believe that whatever you might tell them regarding your cat will simply not cut it.  But this is not true and in more than one times, some of these doctors will allow you to understand what it is that they are doing.

Still, it is your duty to be able to counteract, argue and discuss the treatment options that your kitty will have, regardless of those that are self evident, conditions such as cancer and other auto-immune diseases that are constantly taking a big toll of cats and kittens. 

No one knows your cat better than how you know him or her and you need to make sure that the veterinarian is aware of this; if the doctors suggests one course of treatment that you know that your cat not only will not like but that in addition, could cause him or her to suffer.

Becoming so depressed that he or she might not have the necessary strength to fight the disease back.  Then you need to let him or her know this, so that the course of action taken might differ or be very different from the previously set one.

Just the same, as soon as you see your beloved cat doing things that he or she would not do normally, then it is time to visit the veterinarian.  Some vets will not properly welcome that you are so quickly to take your cat to see them if he or she is not gushing blood; but if you believe that this is the attitude of your current vet, then it might be time to consider switching.

A veterinarian that does not welcome the regular visits of his or her patients is a person who does not understand or welcomes that fact that this is probably the first way to prevent a serious disease to turning into a cause of death.