The State Of The Economy And Dog Adoptions

Those who have experienced job or home loss and can no longer financially support their dogs face a lack of alternatives when it comes to surrendering their pets, leading them to frequently release them to roam freely. When dog owners who employ cruel training methods or engage in illicit breeding cannot find purchasers for their puppies, they often choose to abandon them.

If you are deeply involved in animal welfare, then you should make yourself deeply aware of the economics of pet ownership and animal welfare. National and local economic trends play a significant role in adoptions and pet retention. 

Regarding the meat of the linked article, I don't think you can use selective euthanasia to solve municipal shelter overcrowding issues. Instead, they should be privatized. Microeconomics add up to macroeconomics. All inefficiencies along the supply chain need to be eliminated.