Sometimes you make rash decisions when you're trying to skirt this level of horror.
It's not always that heartless, though. Some people genuinely mean well but just can't help being complete fuck-ups. One man brought in a dog in such bad shape that my co-worker simply looked up and asked him, "When was the last time you saw this dog?" It was inconceivable that a dog could become so ill unless its owner had been given an urgent months-long mission to Russia by his international spy ring (and also traveled back in time to 1956, I guess), leaving the animal with nothing but a 500-lb. bag of food and a prayer. That was pretty much the case, minus the espionage, and as a result the dog withered away with heartworm. The pitiful creature was so close to death, he had maggots on him. And he could have been saved if this guy had noticed the obvious signs at some point before a mysterious hooded figure with a sickle started hanging out in his backyard.
Luckily, his skeletal mouth couldn't whistle or make kissy sounds to call Spot into the grave.
But even among the people who do mean well, you get another problem ...