Like many issues in animal welfare, the answer of why there are homeless animals is not a simple one. There are many reasons for homeless animals. The root of the problem, as with most issues in animal welfare, is irresponsible human behaviour.
Humans who allow reproduction is one of the biggest problems in cats. Too often, people show up the OHS with a litter of kittens. "The mother isn't mine. She has just been living under my porch for the last eight months. I feel sorry for her, so I feed her, " is the common refrain. Guess what? That is your cat. She is in your custody. She is your responsibility.
The second biggest problem is cats that are allowed to roam. It is irresponsible not to have your animal under your control at all times. Cats are subject to all manner of risk: cars, disease, fighting, and too often, intentional harm by neighbours. As many as forty a day end up here at the OHS. Too few owners come looking for their roaming cat and the result is an owner claim rate that hovers around five per cent.
In dogs, the more common problems are poor breeding practices leading to either congenital health or temperament problems, failure to address (or creating) behavioural problems, and failure to plan for emergency veterinary care. All of these result in homeless dogs to be cared for at the OHS—several thousand every year.
In the end, our community doesn't have an animal problem. Our animals have a human problem.