Since this site isn't exclusive for certain people, I'll answer your question. Anyone that stabs a dog to death for any reason is a sick individual ! That's what Animal control is for. Not for someone to take into his own hands. I've been bitten by dogs and never stabbed one. Very cruel and heartless person.
Do you agree or disagree with the vendor's reaction? Chicken rice vendor used a knife to cruelly stab a stray dog that was tied up with the fence. He stated that dog didn't have an owner and once bit his son.
That sick !@#$!
Neither ... Since you don't state where it took place, and it's a matter of perspective.
It would be "horrible" in countries like the US, where dogs are viewed as more family members than livestock ... But not that big a deal in countries where dogs are viewed as another form of livestock.
I mean, unless you're a vegan or vegetarian - you have no issues with a cow, pig, or chicken being treated that way.