While some countries have dogs, chickens, or even goats wandering around outside of a shelter, the most commonly seen outdoor animal in the United States is cats. Though many are feral, a large number of these felines are pets who are kept outdoors.

Some outdoor cats are considered “working cats”—they have a mousing job in a variety of places, such as barns, warehouses, or greenhouses. Many times, cats can be adopted out as working cats, since, prior to being rescued, they lived only outside and wouldn’t do well as indoor-only cats. They may have behavioral issues or too much of a wild personality to live indoors and in a house. However, this does not mean that all cats are meant to be working cats.

Cats who are used to being house pets—especially if they have been declawed—should never be made to go outside without a leash since they have no way to fend for themselves. The danger of permanently losing track of the cat isn’t the main concern because most cats will return to the place where they are given food and attention regularly. Letting a cat roam free when it is unnecessary is a poor idea due to what could happen to the cat while it is outside of the safe walls of the home. This is evident by the fact that on average, outdoor cats live only to be two to five years old, whereas indoor cats can live to be ten to fifteen years and quite often beyond that.

It is not uncommon for cats to fight, especially if both are outside and looking for food. So, many outdoor cats may return with scratches and bite marks that could potentially be fatal. Not only are wounds a danger to felines left outdoors without supervision, but also diseases, viruses, and other sicknesses are as well. Rabies, worms, feline leukemia, fleas, toxoplasmosis, feline herpes, and immunodeficiency virus are just a few of the many illnesses that outdoor cats can contract and spread if they are permitted to wander. Many of these are life-threatening and could permanently affect the well-being of the cat.

Not only can having an outdoor cat be damaging to the cat but also to the environment. When a cat is placed outside in a suburban yard, it is being introduced to an ecosystem that it is not native to. As taught in basic biology classes, all species and factors are closely intertwined in an ecosystem, and if a new species is thrown in or pulled out suddenly, all of the other organisms will be affected. While working cats may snatch up the occasional mouse that scurries through the barn, a suburban, outdoor cat left to venture out on its own will certainly catch more than rodents. Unfortunately, birds, reptiles, and small mammals are all victims of outdoor cats, some of which are endangered.

Domestic cats have led to the extinction of 33 species, and many of the kills they make aren’t even beneficial to the cat. Even if they are well fed, cats will kill just out of instinct, leading to the meaningless death of many creatures. When the prey that wild animals would normally feed on has a low population due to outdoor cats overhunting, the wild predator populations would be affected as well.

Though outdoor cats can be beneficial and a great option for formerly feral cats when used to catch mice in a barn or other structure, pet cats should always remain indoors. If a cat is insistent on exploring the outdoors, a leash and harness, while potentially an amusing sight, could be a wonderful resource for cats to safely enjoy nature without posing a threat to themselves and native species.