In hind-sight, I think I may have been a little harsh.
For myself, I can tell you two stories....
Whilst back packing through Indonesia, in a predominantly Muslim region of Java, I think, I happened upon a dog being teased by many local kids. This dog was a surviving runt of a litter, it was in one Hell of an awful state, it swayed and staggered like a blind drunk, it’s body was distorted and ravaged, I’ve never seen a creature even vaguely similar to this animal. I asked the hotel owner about it and he stated they never do anything about such animals, let alone a mercy killing.
This is the 1st time I’ve ever related this story; so after a while of observing the constant harassment of this creature, I took the dog out into the surf & strangled it. I looked into its eyes as this seemed somehow the right thing to do, if not for him, but for me. I still have a strange rash on my wrist from this dog. Soon after, it was suggested that I leave the town.
Another incident was whilst backpacking in Egypt on the Red Sea. A local feral cat had been knocked down by a car and was in constant pain, lying up in the shade of a bush. No one wanted to do anything about it, no vet would be called and people found it humorous in some way. I established up front if anyone owned the animal and was pretty much laughed at!
I took a milk crate, which was more gaps and holes than plastic, managed to get hold of the cat & walked out into the sea, and again I performed a mercy killing.
Sometimes action is called for and I have no regrets about my having the courage of my convictions with regard to both the dog and the cat, but I still think about both animals and hope that my actions lessened their pain.