Pet, Companion?

I figure that different dictionaries probably give similar definition of "pet" or "companion," so I simply used wikipedia dictionary.
Pet (plural pets)

1. An animal kept as a companion.
2. One who is excessively loyal to their superior.

Companion (plural companions)

1. A friend, acquaintance, or partner; someone with whom one spends time or keeps company
   
   His dog has been his trusted companion for the last five years.
   
2. (dated) A person employed to accompany or travel with another.
3. (nautical) The framework on the quarterdeck of a sailing ship through which daylight entered the cabins below.
4. (nautical) The covering of a hatchway on an upper deck which leads to the companionway; the stairs themselves.

Synonyms friend

 

Here, I am talking about cats and dogs. Perhaps also fish, turtles, snakes, and other non-economical animals. The meaning of pet and companion seems overlapping. By logic, a pet is a companion; therefore, it is a friend. But in my opinion, pet and companion are somewhat different. By using the term pet, it is still considered as an "animal." On the other hand, when I say companion, an animal is being personified. Companion is our soul mate and true friend.

Companion cannot be given away. We don't abandon our friends when they get sick. We might fight with them sometimes, and in some extreme cases, we sever the relationship – divorce, breakup, spilt up. However, we don't give them up for reasons like "I am getting pregnant so I have to give my cat away" or "because my future mother-in-law doesn't like dogs so I am giving them away" or "the cat popped in my bed too many times."

When a family member is ill, we do everything we can to save them, care them, treat them. Pet? Well, some people simply think their life value less than mankind. They don't deserve or require intense care. It is ridiculous to spend thousands of dollars in medication, food, or toys. Here is not to judge, but ain't that irresponsible?