Eutanasia - Mercy or cruelty?

A few days ago I was watching a documentary about a veterinary station. They showed a little dog who had been tortured by its previous owner. The little animal's legs had been broken and had healed the wrong way so the poor fellow was in pain with every step he did. So after a difficult conversation, the vet and the dog's new owner decided it was the kindest to put it down. This actually made me think. 

While we consider it being merciful to put down an animal who is suffering, without the animal even able to voice its opinion, most people are repelled if a person suffering from a painful and terminal disease voices the request for eutanasia. Don't get me wrong I am well aware that there is a huge difference between animals and human beings, but the animals are not even requesting help, while the humans do. Are we granting animals a mercy we deny humans? 

There is a large variety of laws in different countries from actual permission to complete illegality concerning eutanasia, which in a way is surprising as, when it comes to this situation nationality, money, education etc. doesn't really matter anymore, as all men are truely the same when it comes to death. 

Of course a huge factor in the judgement of eutanasia is usually religion and this might in a way explain why the legal approach to eutanasia is so different in various countries.

But instead of discussing laws I wonder if the approach shouldn't be a different and yet simple one: What is the right thing to do for people who are actually suffering? If we are consequent the laws are what should follow once this question is answered.

If a person is suffering from a painful and lethal  disease and is of sound mind and disposing memory and asks for help to end his life do we really have the right to forbid that? If you are thinking "no" ask yourself "why"? Is it for the person that is suffering or for the people around him. Shouldn't the right to command over his own life be the ultimate freedom for a person (Of course always in terms with sanity!)? 

To be absolutely clear this statement is only meant in terms of eutanasia an NOT in terms of suicide. If a person who is healthy thinks about suicide this person clearly needs psychological help. The main difference is that a person requesting eutanasia will not get better, their disease is lethal and painful, their situation won't improve and they are mentally stable, while a fisically healthy person thinking about suicide is mentally ill and can be helped. 

When thinking about this topic I was of course confronted with religious views and have decided not to go into this aspect. If there are literally dozens of laws there are at least ten times more rules applied by religions. I consider this question is equally important for all mankind independently from their religion because after all we are all human beings not matter how we say our prayers. 

So the question has to be if there is a simple right or wrong in the matter or if it is more complex? Isn't it at the same time selfish of a dying person to ask someone for help in killing themselves and to burden this on the other persons soul? Because no matter how you decide in such case you will have to deal with a lot: You either help someone to end their life or you have the knowledge that you prolonged  person's suffering  by denying the help. 

Usually I conclude with my own opinion but in this case I won' t do it, as honestly I really cannot come to a conclusion on what is right or wrong in this matter. I am thankful I have never been in such situation where I had to decide and I dearly hope I never will.