The Lied Animal Shelter, though it wanted to be, is not a shelter. It is what used to be called, many centuries ago, a "pest house". The old name has a very modern resonance. "Pest" is short for "pestilence" and the dogs and cats that were warehoused until they were killed for being diseased were society's "pest-pets" - pet animals that are not wanted by anyone.
Every unwanted or sick animal is a problem to society. Just like rats and raccoons, dogs and cats and rabbits can be a public health, safety, and nuisance problem.
There are businesses that for money, openly and honestly rid society of wild pests such as rats and raccoons. And there businesses that rid society of pest-pets too. The honest ones are called pounds. The dishonest ones call themselves "shelters".
The Lied Animal Shelter was not a shelter, but because that is what it called itself, everyone repeats it parrot-like. It was the pound for Clark County. It was society's pest-pet disposer for a densely populated area. It had to take stray dogs and it chose to take surrendered cats and dogs.
Choosing to take all surrendered pets must result in killing for disease and for space as this example (and thousands of others) shows. There is no other option, not when there are more pets than new homes for them as is still the case everywhere, in BC as well as in Clark County.