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Managing existing parasitic conditions and immunizing against ailments such as rabies are crucial safeguards, even for felines that remain indoors. (Image credit: Liudmila Chernetska)
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Many individuals consider pets to be a significant part of their lives, offering valuable companionship. However, our animal companions can occasionally be a vector for undesirable microorganisms and illnesses, especially if they frequently venture outside.
We are professionals in ecology and veterinary medicine who investigate the health of wild animals and the transmission of pathogens between wildlife, domestic animals, and humans. If your cat spends time outdoors, or if neighborhood cats enter your yard, our recent discoveries could be pertinent.
Pathogenic organisms that can infect both animals and people are termed zoonotic. From a microorganism’s viewpoint, humans are simply another animal host. Wildlife is frequently highlighted as a source of novel diseases for humans because there are considerably more species of wild animals than domestic ones.
Nevertheless, even if a pathogen has the capacity to infect humans, it requires a transmission route. Humans share a greater number of zoonotic pathogens with domestic animals than with wild animals, due to the close proximity in which domestic animals live with us. Pathogens gain an even greater advantage if they can infect a pet.
In our recently published study, we synthesized information from over 400 investigations to examine how a cat’s lifestyle—whether primarily indoors, allowed to roam outside, or living feral—influences its probability of harboring pathogens transmissible to humans.
Throughout this compilation, approximately 100 pathogens detected in cats were identified as zoonotic and capable of human infection. Common examples include rabies, *Toxoplasma gondii*, roundworms, and *Salmonella*.
Our research
We determined that pet cats permitted to roam outdoors had a three to fivefold increased likelihood of carrying a zoonotic pathogen compared to cats kept exclusively indoors. More remarkably, cats with outdoor access exhibited a similar probability of carrying at least one zoonotic pathogen as feral cats. While outdoor-dwelling owned cats carried fewer types of pathogens than feral cats, the same pathogens that affect feral cats can also infect owned cats.
These risks escalate to a widespread issue because freely roaming pet cats engage in close contact with humans, wildlife, and other domestic animals. Based on the studies reviewed, approximately 60 percent of owned cats had access to the outdoors unsupervised; in certain regions, this figure surpassed 90 percent.
Cats that roam hunt, interact with wild animals or other domestic pets, and traverse environments potentially contaminated with pathogens and toxins. Research indicates that cat owners may underestimate their pets’ hunting activities by roughly 80 percent, meaning numerous captures of prey and animal encounters go unobserved.
These types of interactions are not infrequent and are not confined to species typically considered pests. Estimates for wildlife fatalities caused by cats within a single country reach into the billions, with over 2,000 distinct wildlife species documented as prey for domestic cats.
Cats prey on animals that can carry zoonotic pathogens, including rodents, birds, and bats, many of which would otherwise have minimal direct contact with humans.
(Image credit: Anton Darius)
Cats hunt creatures that can harbor zoonotic pathogens, such as rodents, birds, and bats, many of which would typically have little direct interaction with people. Owned cats might bring home rodents infected with viruses, and documented instances exist of cats delivering rabies-positive bats into residences. Consequently, a cat returning with prey can establish a pathway for pathogens circulating in wildlife populations to reach humans.
Furthermore, the risk is not confined to pet owners. Cats that roam outdoors deposit feces in gardens, parks, playgrounds, and other communal areas, potentially leading to significant levels of contamination. One study estimated that outdoor cats deposited over 60 metric tons [60 tons] of feces annually per 10,000 households.
Depending on the specific parasite, feces can contain hundreds to hundreds of thousands of parasite ova that can remain viable in soil or water for months to years, posing a risk of infection to humans or other animals that come into contact with them.
What cat owners can do
The most direct measure, which is also the most cost-effective and humane, is to prevent unsupervised outdoor access. This does not necessitate denying cats the opportunity to experience the outdoors. It can involve constructing “catios” or enclosed spaces, utilizing leashes for walks, allowing supervised outdoor time, or employing other methods of contained outdoor enjoyment.
Implementing systems like “catios” or utilizing leash walks can help reduce pathogen exposure for cats.
(Image credit: Carlos G. Lopez)
Veterinary attention remains significant. Addressing existing parasitic infestations and obtaining vaccinations against diseases like rabies are vital protective measures, even for cats confined indoors. Since neither vaccines nor antiparasitic treatments encompass the full spectrum of wildlife-associated pathogens, managing exposure emerges as the more comprehensive approach to protection.
The discussion surrounding free-roaming cats is frequently presented as an unresolvable dichotomy: either cats roam freely, or their natural behaviors are suppressed. This framing is inaccurate and inconsistent with how we manage other companion animals.
We do not presume that dogs require unrestricted access to roadways, neighboring properties, or the ability to hunt wildlife for their welfare to be optimal. Indoor cats and cats with opportunities for supervised outdoor exploration can lead healthy, fulfilling, and longer lives.
Policies and strategies that govern how and where owned cats roam outdoors can contribute to preserving biodiversity, the well-being of felines and wildlife, and public health. This aligns with the core principle of One Health, recognizing that the same choices that protect ecosystems can simultaneously safeguard the animals and people who inhabit them.
This article was collaboratively written by David Lapen, who is employed by and receives research funding from Agriculture and Agri-Food Canada.
This revised article is reprinted from The Conversation under a Creative Commons license. Access the original article here.
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