I am not one to keep pets. For me, they are too much work, especially that I have two kids to take care of and a career to keep.
When I was a kid living with my parents though, we had dogs. But they serve mostly as guards in the house. They are not really for companions. We had no personal relationship.
But those who keep pets as friends should really take good care of their animals. They should be given ample care because then the affection is reciprocated. If they get sick, they should really be brought to the veterinarian so that they can be given appropriate prescription pet medications.
Yes, pets should be properly diagnosed and given proper medication. You cannot just give them anything. And of course, there is the dosage that you have to think of. So you have to be careful otherwise they can get sicker.