Getting into some philosophical stuff here - I`m loving it!
In my way of thinking - no.
I think you gotta differentiate between two sphere`s here.
The first, would be the one where you define an item/object/being for it`s use.
The second would be to put your findings into the context for the person.
So, following that strain of thought, there`d be a difference between Fiona the cat, which is dearly loved by her owner, and Hachiko (name just got into my brain - you gotta watch the movie, which has the same name!) the service animal.
While there`s "only" an emotional bond with the first animal, the second is compensating for a physical deficit of it`s owner. The best example would be a seeing-eye-dog.
Now, I guess, in the mind of it`s owner, Hachiko would be "linked" to his ability to compensate for his loss of the sense (seeing). So, if you`d take away the dog, it would be like taking away his ability to "see" the outside world (`cause his doing that through his dog in a crude way).
So, even if the doggies service isn`t really needed, `cause the pat. is in a safe enviroment, I think he would experience the parting of the animal as a loss of his sense.
Example:
You`re living on an island - which you don`t need to leave, though it`s reassuring to know there`s a bridge to the mainland if you ever feel the need to get out of there.
Even if you don`t need to leave the island, wouldn`t it be bad to know that the bridge got burned down (assuming it`s a wooden bridge).
To clarify - I`m only going into the extent of the emotional part, of course, this is no argumentation for any legal responsibility and it`s just guesswork/my thoughts,