Cats: Why They Should be Enclosed and Not Roam Free


By Michael W. Fox BVetMed, PhD, DSc, MRCVS

As will be documented in this review, one of the greatest animal health and welfare, wildlife conservation and public health concerns which are not being fully addressed in the U.S. and most other countries, and which can be quickly remedied by public education and legislation, is owned cats being allowed to roam free and un-neutered cats establishing feral populations in urban and rural communities and invading natural ecosystems.

I love cats as well as all creatures wild and domesticated and am very opposed to allowing them to roam free. There is an estimated 24.5 million owned cats in the U.S. ( Source: 2017-2018 U.S. Pet Ownership & Demographics Sourcebook ). Unfortunately, there are no rigorous estimates for the number of feral cats living in the United States. The best available estimate suggests that the population is probably about 32 million, roughly 76% of whom live in urban areas. (Source: If half of America’s cat owners let their cats outdoors, this means there are around 44 million cats roaming free, at risk and putting wildlife and public health also at risk.

WIDLIFE CONCERNS: Free-ranging domestic cats kill an estimated 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually. (Source: Cats compete with indigenous wild carnivores, including raptors, for prey and can spread diseases to them and bring home diseases from them as well as from the prey they consume. Millions of cats live in two worlds as indoor-outdoor animals (still a cultural norm in the U.K. and many other countries) and often bring home wild animals they have killed or injured such as chipmunks, voles, baby rabbits, chickadees and lizards, require veterinary treatments themselves for injuries and diseases as well as their owners who contract various infections and confront infestations that these cats bring back into their homes and beds. (For more details see the review article Also, for the humane alternative of TNE ( trap-neuter-enclose) to TNR ( trap-neuter-release) visit


Insectivorous birds like Barn Swallows, Swifts, Nighthawks, Purple martins, Eastern kingbirds, Sparrows, various migratory songbirds especially Warblers, like Blackpoll and Yellow warblers, Bluebirds. Eastern phoebes. House wrens. Hummingbirds, Baltimore Orioles and Red-eyed vireos are known for eating flying insects, including mosquitos. Many of these birds fall prey to free-roaming cats who, in turn, by reducing this natural mosquito control by birds, put humans and other animals at risk from mosquito-borne diseases. These include heart-worm disease (dirofilariasis) which is increasing in dogs, cats and humans. According to The United State Centers for Disease Control and Prevention (CDC) mosquitoes kill more than one million people a year just from the transmission of malaria. Scientists are concerned global warming could lead to the explosive growth of mosquito-borne diseases worldwide, some of the most common diseases spread by mosquito bites include Zika virus, West Nile virus, chikungunya virus and dengue fever, There is no vaccine to prevent or medicine to treat most of these diseases. So one prevention is to keep cats indoors or suitably enclosed to protect insectivorous birds.

Most municipalities in the U.S. use sprays to kill adult mosquitoes and pellets of insecticides spread often by helicopters over lakes to kill mosquito larvae. But in the process, they kill beneficial aquatic insects and other aquatic species that would consume the mosquito larvae while insectivorous reptiles, amphibians, bats and birds starve to death because their main food source of mosquitoes and other beneficial insects This loss of biodiversity, exacerbated by herbicides and insecticides used in agriculture, forestry and by gardeners, leads to dysbiosis and the proliferation of disease-transmitting chemical-resistant insects, notably sandflies, ticks and midges as well as various mosquito species.

Few municipalities have any effective ordinances mandating keeping cats indoors or enclosed on private property, creating a perfect storm, now exacerbated by climate change in many areas with increased rainfall and humidity and mosquitoes becoming insecticide-resistant. Thus a perfect storm is created for the spread of mosquito-borne diseases in communities that can sicken and kill people, companion animals, livestock and wildlife.

NOTE: Two people in Delaware tested positive in Oct. 2021 for West Nile virus, and an unvaccinated horse with WNV was euthanized Oct. 5 after the animal became unable to stand. Both West Nile virus and Eastern equine encephalitis can be fatal to equids, and owners should “work with their veterinarian to set up a routine vaccination protocol,” said Deputy State Veterinarian Karen Lopez .Full Story: WBOC-TV (Salisbury, Md.) (10/8/21)


For centuries we have used cats especially around our properties and farms, warehouses and docks to control rodents. Such cultural tradition and acceptance needs to be questioned from cat cat health and welfare perspective and from the perspective of public health. The common situation down on the family farm was litter after litter of kittens from non-neutered resident cats most of whom died from infections or were put in a gunny sack and drowned or smashed against a wall or rock, which I have witnessed.

A full reassessment from the public health perspective would call an end to “Working Cats” who can pick up fleas from rats and other wildlife and spread plague into our communities: and a much more prevalent infection: Toxoplasmosis. This disease circulates between cats, the primary host, and rodents who become infected by the cats and in turn, infect other cats ( and wild predators) when they are consumed. It also spills over to other species, not only wildlife but to farm animals when infective cat feces contaminate their feed and where they graze. They, in turn, infect people, as do in-home, and often outdoor-indoor infected cats. Toxoplasmosis is a disease infecting 11% of the U.S. population and some 60% worldwide. Several countries find pork, beef, poultry, dairy products and rabbit meat testing positive for this ubiquitous parasite putting consumers at risk. It is notable that the decline in pigs testing positive in the U.S. is attributed by the U.S.D.A. to hog factory operators keeping cats away from their farms.

The logical solution is to make it mandatory to keep cats away from farmed animals ( also those in zoos) and to make all animal feed-storage areas rodent-proof without the use of rodenticides which poisoned rodents can transfer to wild predators-snkaes, foxes, raptors, who consume them and become poisoned.


In their review article “Rabies Prevention and Management of Cats in the Context of Trap, Neuter, Vaccinate, Release Programs”, veterinarians and scientists Allison D. Roebling, MPH, DVM, Dana Johnson, DVM, Jesse D. Blanton, MPH, Michael Levin, PhD, Dennis Slate, PhD, George Fenwick, PhD ,and Charles E. Rupprecht PhD summarize their findings as follows::

“Domestic cats are an important part of many Americans’ lives, but effective control of the 60–100 million feral cats living throughout the country remains problematic. Although Trap-Neuter-Vaccinate-Return (TNVR) programs are growing in popularity as alternatives to euthanizing feral cats, their ability to adequately address disease threats and population growth within managed cat colonies is dubious. Rabies transmission via feral cats is a particular concern as demonstrated by the significant proportion of rabies postexposure prophylaxis associated with exposures involving cats. Moreover, TNVR has not been shown to reliably reduce feral cat colony populations because of low implementation rates, inconsistent maintenance, and immigration of unsterilized cats into colonies. For these reasons, TNVR programs are not effective methods for reducing public health concerns or for controlling feral cat populations. Instead, responsible pet ownership, universal rabies vaccination of pets, and removal of strays remain integral components to control rabies and other diseases.” (Citation from Zoonoses Public Health. 2014 Jun; 61(4): 290–296. Published online 2013 Jul 17. doi: 10.1111/zph.12070)

Rabies, Cats and Coyotes.

While non-profit organizations like are helping communities live in greater harmony with coyotes who are moving into many previously coyote-free places across the U.S., many wish for their extermination, fearing rabies. This disease is transmitted by the bites and saliva of infected animals, Each year, rabies causes approximately 59,000 deaths worldwide. In the CDC’s 2020 rabies surveillance report ( only 11 coyotes tested positive as compared with a total of 288 cats, a number that has increased from 245 reported in 2019. Only 57 dogs tested positive in 2020, a drop from 66 in 2019.

Municipalities need to consider these findings and take every measure to improve public health standards by mandating, as with dogs, rabies vaccinations for all owned cats and not allowing cats to roam free in their neighborhoods. Many such communities have skunks, raccoons, foxes and bats who, as this CDC report documents, serve as reservoirs for rabies infection. This could be quickly passed on to outdoor cats and then from the cats to people when they return home or when they bite people who contact them outdoors. This virus affects animals’ brains and is appropriately called ‘le rage’ because infected animals are hyper-aggressive and bite at whatever they can, as I have witnessed working at the animal hospital and refuge my wife Deanna Krantz founded and ran in S. India over a decade ago.

All engaged in TNVR-trap, neuter-vaccinate (against rabies) and release “community cat” programs should cease and desist because these cats can rarely be trapped again for needed re-vaccination if they survive such inhumane abandonment. While it is true that cases of cat-to-human rabies infection are rare in the U.S., the incidence of rabies in wildlife is on the upswing, increasing the risk of cats becoming infected: And, as the CDC notes: “The number of human rabies deaths in the United States has been steadily declining since the 1970’s thanks to animal control and vaccination programs, successful outreach programs, public health capacity and laboratory diagnostics, and the availability of modern rabies biologics. Yet each year, hundreds of thousands of animals need to be placed under observation or be tested for rabies, and between 30,000 to 60,000 people need to receive rabies post exposure prophylaxis.”


Researchers distributed GPS tracking backpacks to pet owners in six countries, including the United States, United Kingdom, Australia, and New Zealand. They collected data on both how far 925 pet cats roamed and how many animals they hunted down. Pet cats kill between two and ten times more wildlife than native predators, the researchers found.

“Our research shows that pet cats can have a large impact on prey populations, but that this is mostly localized near their houses,” said Roland Keys, lead author and a professor at North Carolina State University, in a video accompanying the study. Paired with the fact that house cats tend to live in close quarters with one another, our pets’ collective killing power can be four to 10 times greater than that of wild animals. All of this evidence adds up to one, straightforward solution to protect wildlife populations, Kays says: Keep your cat inside.

R.Kays et al The small home ranges and large local ecological impacts of pet cats. Animal Conservation 11 March 2020 Abstract: Domestic cats are a conservation concern because they kill billions of native prey each year, but without spatial context the ecological importance of pets as predators remains uncertain. We worked with citizen scientists to track 925 pet cats from six countries, finding remarkably small home ranges (3.6 - 5.6 ha). Only three cats ranged >1 km2 and we found no relationship between home range size and the presence of larger native predators (i.e. coyotes, Canis latrans). Most (75%) cats used primarily (90%) disturbed habitats. Owners reported that their pets killed an average of 3.5 prey items/month, leading to an estimated ecological impact per cat of 14.2-38.9 prey ha-1 yr-1. This is similar or higher than the per-animal ecological impact of wild carnivores but the effect is amplified by the high density of cats in neighborhoods. As a result, pet cats around the world have an ecological impact greater than native predators but concentrated within ~100m of their homes.


Cats allowed off their property can get lost, hit and injured or killed by traffic, coyotes, dogs and other large animals as well as being trapped, shot, poisoned, bitten and infected by other cats, notably with feline AIDS and get feline infectious leukemia and other viral infections. Cats with feline panleukopenia have infected and killed endangered Florida panthers.

Domestic cats also carry feline viral diseases such as feline leukemia virus which has infected and killed endangered Florida panthers. ( See Multiple Introductions of Domestic Cat Feline Leukemia Virus in Endangered Florida Panthers by Elliott S Chiu, Simona Kraberger, Mark Cunningham et al Emerg Infect Dis 2019 Jan;25(1):92-101. doi: 10.3201/eid2501.181347.)

Feline distemper, also called feline panleukopenia, is an acute, highly infectious viral disease common in unvaccinated domestic cats that can affect other members of the Felidae, (bobcat, lynx,) and Procyonidae, (raccoon) and Mustelidae.( ferret, mink, weasel, marten, fisher, otter, badger, skunk, wolverine) ( See,4570,7-350-79136_79608_85016-26505--,00.html).

Feline AIDS or feline immunodeficiency virus has also been detected in Florida panthers.( See Miller, D.L., Taylor, S.K., Rotstein, D.S. et al. Feline Immunodeficiency Virus and Puma Lentivirus in Florida panthers (Puma concolor coryi): Epidemiology and Diagnostic Issues. Vet Res Commun 30, 307–317 (2006). )

Pumas, bobcats, and domestic cats are sympatric in many areas of North America and share many of the same pathogens, some of which are zoonotic. Researchers analyzed bobcat, puma, and feral domestic cat samples collected from targeted geographic areas. They examined exposure to three pathogens that are taxonomically diverse (bacterial, protozoal, viral), that incorporate multiple transmission strategies (vector-borne, environmental exposure/ingestion, and direct contact), and that vary in species-specificity. (See Sarah N. Bevins, Scott Carver, Erin E. Boydston et al Three Pathogens in Sympatric Populations of Pumas, Bobcats, and Domestic Cats: Implications for Infectious Disease Transmission PLoS One. 2012; 7(2): e31403. 10.1371/journal.pone.0031403 They reported: “Bartonella spp., Feline Immunodeficiency Virus (FIV), and Toxoplasma gondii IgG were detected in all three species with mean respective prevalence as follows: puma 16%, 41% and 75%; bobcat 31%, 22% and 43%; domestic cat 45%, 10% and 1%. Bartonella spp. were highly prevalent among domestic cats in Southern California compared to other cohort groups.

Feline Immunodeficiency Virus exposure was primarily associated with species and age, and was not influenced by geographic location. Pumas were more likely to be infected with FIV than bobcats, with domestic cats having the lowest infection rate. Toxoplasma gondii seroprevalence was high in both pumas and bobcats across all sites; in contrast, few domestic cats were seropositive, despite the fact that feral, free ranging domestic cats were targeted in this study. Interestingly, a directly transmitted species-specific disease (FIV) was not associated with geographic location, while exposure to indirectly transmitted diseases – vector-borne for Bartonella spp. and ingestion of oocysts via infected prey or environmental exposure for T. gondii – varied significantly by site.”

See also Frequent cross-species transmissions of foamy virus between domestic and wild felids .by Kraberger S, Fountain-Jones NM, Gagne RB,et al Virus Evol. 2020 Jan 12;6(1):vez058. doi: 10.1093/ve/vez058. eCollection 2020 Jan.PMID: 31942245 Assessing cross-species transmission of hemoplasmas at the wild-domestic felid interface in Chile using genetic and landscape variables analysis .by Sacristán I, Acuña F, Aguilar E, et al Sci Rep. 2019 Nov 14;9(1):16816. doi: 10.1038/s41598-019-53184-4.). Feline calicivirus can be passed on from infected cats to other wildlife according to a study by Seth P. D. Riley, Janet Foley, and Bruno Chomel. Exposure to feline and canine Pathogens In Bobcats and Gray Foxes in Urban and rural Zones of a National Park in California. Journal of Wildlife Diseases, 40(1), 2004, pp. 11–22 q Feline parvovirus, which has a high incidence in unvaccinated cat populations, can also be passed on to raccoons and foxes .( PARVOVIRUSES (PARVOVIRIDAE) | Cats, Dogs and Mink Colin R. Parrish, in Encyclopedia of Virology (Second Edition), 1999)

Feline scabies (Notoedres cati and Sarcoptes scabiei ) are a parasitic skin infestation which can decimate wolf packs and infect foxes, coyotes, bobcats and other wildlife as well as humans and can be spread by free-roaming cats infested by these mites.


Ear mites (Otodectes cynotis) are a common cause of chronic ear infection, a condition called otitis externa with itching/ pruritus, in cats and dogs worldwide. The mites cause much suffering and even loss of hearing if untreated, and scratching and head-shaking can result in hematomas ( blood clots) in the ears which eventually cruple into ‘cauliflower ears”. Some cats with ectopic mites present with generalized alopecia and pruritus similar to flea allergy dermatitis.

This common parasite, which can be transmitted to and from other wildlife such as foxes and coyotes, calls for all TNR cat colonies and indoor-outdoor cats to be regularly examined and treated as needed since it is such a prevalent parasite.(Akucewich LH, Philman K, Clark A, et al. Prevalence of ectoparasites in a population of feral cats from north central Florida during the summer. Vet Parasitol. 2002;109(1-2):129-139.Thomas JE, Staubus L, Goolsby JL, Reichard MV. Ectoparasites of free-roaming domestic cats in the central United States. Vet Parasitol. 2016;228:17-22.).

CATS KILLING SONGIRDS AT RISK FROM “SONGBIRD FEVER” Birds can carry Salmonella bacteria which can make cats ill and even die from this bacterial infection which can also be passed on from the cats to humans in the home.

Cats can play a role in the spread of other emerging diseases like Q fever (Meredith AL, Cleaveland SC, Denwood MJ, et al. Coxiella burnetii (Q-Fever) Seroprevalence in Prey and Predators in the United Kingdom: Evaluation of Infection in Wild Rodents, Foxes and Domestic Cats Using a Modified ELISA. Transbound Emerg Dis. 2015 Dec;62(6):639-49. doi: 10.1111/tbed.12211. Epub 2014 Jan 31. PMID: 24479951.)

Rather than offering more supportive citations to stress the urgent need to protect all wild felids like Bobcats, Lynx and Panthers/Cougars and other wildlife species, not simply from the competitive predation by domestic cats but from diseases they can contract from infective cats, better community control of domestic cats coupled with owner-education and legislation to not allow cats to roam free are called for. But this is not to discount the significance of competing with indigenous predators for food/prey.


Outdoor cats who are not treated for bot and other fly maggot infections develop chronic secondary infections and suffer considerably. Several fly species can infect wounds, causing a condition called myiasis. According to one extensive review (Pezzi M, Bonacci T, Leis M, et al, Myiasis in domestic cats: a global review. Parasit Vectors. 2019 Jul 29;12(1):372. doi: 10.1186/s13071-019-3618-1. “Factors favouring the occurrence of myiasis in cats are prowling in infested areas, poor hygiene conditions due to diseases and/or neglect, and wounds inflicted during territorial or reproductive competition.”

According to a posting on this subject, ( “Cats are accidental hosts of Cuterebra larvae. They are most commonly infected when they are hunting rodents or rabbits and encounter the botfly larvae near the entryway to a rodent’s burrow. The adult botfly deposits its eggs near or in the opening of rodent and rabbit burrows. After hatching, the botfly larvae, which typically infect rodents and rabbits, enters the host’s body through an opening such as the nose or mouth or through a skin wound. After several days, the botfly larvae migrate to the tissues beneath the skin where they encyst and continue their development. Most cases of warbles in cats occur around the head and neck. Most cats will develop a deep abscess or skin infection at the infection site after the warble has left the skin. How can I prevent my cat from getting warbles? The best prevention is to keep your cat from hunting rodents.”


Several sources estimate that the life expectancy of an outdoor cat is only 2–5 years. By contrast, the life expectancy of an indoor-only cat is nearer 12–18 years (even up to 20 years!). One major reason for the shorter lives of cats allowed outdoors is because when they enter another cat’s territory-which could be a feral cat’s or a no -less irresponsible neighbor’s, cat, bite wounds can transmit FIV-the usually fatal feline immunodeficiency virus. Aside from being hit by vehicles, the other major cause of considerable suffering and expensive veterinary treatment is for cat fight injuries from claw-puncture wounds to deep bites transmitting bacterial infection into underlying tissues, muscles, tendons and joints. These wounds can be crippling and lead to septicemia—blood poisoning—and a slow death if the cat is not immediately treated.

Every veterinary hospital will attest to the fact that many of their feline patents come in with bite and scratch wounds, usually from other cats and on occasion from wildlife such as foxes, raccoons and coyotes . Some of these poor cats had no defense since their owners had them declawed. Other owners let their cats out “because they wanted out.” Neutering and the company of another cat indoors generally prevents this desire.

I am especially concerned about TNR “Community Cat” programs that do not provide any protective enclosure for their cats which means that any free-roaming and wide-ranging stray, feral or outdoor-indoor Tom cat could encounter and injurious fighting occur. Catching TNR cats with fight injuries would be challenging and probably too little too late if the injured and suffering animal is actually caught. “Working Cats” with infected bites and scratches are likely to die slowly from a combination of infection and starvation, being too ill or crippled to hunt. For more details go to


Often under-diagnosed when cats go blind or develop a fever, become lethargic, anorexic, lameness, skin nodules and respiratory distress, histoplasmosis is a fungal disease in the soil. It is the second most commonly reported fungal infection in cats, following cryptococcosis.

Cryptococcosis is a type of fungal infection that occurs when a cat inhales spores from a type of fungus that grows in organic material such as soil, decaying wood, or bird guano (especially droppings from pigeons). Spores also can enter the skin through an open wound. Since these fungi are everywhere in the soil, cats are likely to get the soil on their paws and ingest it when grooming, along with fungal spores. The spores could be inhaled or get into the fur in dry and dusty weather and when cats dig into the soil chasing small rodents or making a pit in which to defecate. The fungal diseases are a major reason to keep cats indoors and never use soil in the cat’s litter box.


The incidence of oral, squamous cell cancer in cats, which is generally fatal, is estimated to account for 3% of all feline cancers. It can be avoided. The research study Environmental risk factors for the development of oral squamous cell carcinoma in cats by Riccardo Zaccone et al 27 May 2022 identifies two major risk factors: outdoor access and petfood containing chemical additives. So, the best preventives are to keep cats indoors and feed good quality, ideally Organically Certified and at least additive- free cat foods, or make your own as per my recipe posted at


Indoor cats are upset by cats outdoors their reactions including redirected aggression toward their owners and companion cats in the home; spraying/territorial marking and stress-related cystitis and other health issues such as excessive grooming and house-soiling. These latter behavioral problems can mean abandonment, surrender to a shelter and euthanasia.

Uninformed cat owners who do not neuter their cats, especially young tom cats, often finish up letting their cats out if they do not actually escape, when they start to spray, stink up the home and are hormonally-driven to get outside to mate.

Some of the reasons and solutions to enhance their overall health, safety and well-being are detailed in the American Bird Conservancy’s Cats Indoors Program: “Ever since the invention of kitty litter, cat owners have realized the many benefits of keeping their furry companions safely indoors, on a leash, or otherwise safely contained. This transition has enabled cats to live longer and healthier lives, resulting in fewer trips to the veterinarian and extending the years of mutual companionship. Keeping cats safely contained also protects birds and other wildlife from a cat’s instinctive predatory drive.” For details, and for local Humane Societies and cat rescue organizations to promote visit

The Association of Fish and Wildlife Agencies (AFWA), in collaboration with American Bird Conservancy and other partners, has published a comprehensive domestic cat management guide. The “Toolkit to Address Free-ranging Domestic Cats (Felis catus) on Agency Lands Managed for Native Wildlife and Ecosystem Health” covers a range of topics including predation and disease concerns, legal and policy issues, and management solutions. The toolkit is the result of work by AFWA’s Feral and Free-ranging Cat Working Group, which will soon release more detailed guidance on model policies and an updated AFWA resolution on the control of free-ranging domestic cats. Schweitzer, S.H., and C.M. Gillin (eds.) 2020. Toolkit to Address Free-ranging Domestic Cats (Felis catus) on Agency Lands Managed for Native Wildlife and Ecosystem Health. 32 pages.

One Health is a collaborative strategy, supported by the Centers for Disease Control and Prevention, for achieving optimal health outcomes that recognizes the interconnectedness of domestic animals, wildlife, the environment, and people. American Bird Conservancy recently published an overview of One Health and its relationship to the Cats Indoors program. See One Health, Domestic Cats, And Zoonotic Diseases Grant Sizemore August 30, 2021

Mr. Sizemore writes “Our Cats Indoors program educates the public and policy makers about the many benefits to birds, cats, and people when cats are maintained indoors or under an owner’s direct control. In addition to advocating for responsible pet ownership solutions, we also oppose Trap, Neuter, Release (TNR) for feral cats because of the persistent and severe threats posed by these cats on the landscape.” Kwame Anthony Appiah, writer of the New York Times “The Ethicist” column, reported on the ethics of keeping cats indoors. Appiah commented that “responsible animal-rights groups now agree that our feline companions should not be left to roam free.”

Many people have improved the quality of life and overall well-being of their cats by first, having two or more cats rather than one, and secondly, providing access via a flap door set in a window pane or outside door to an enclosure as per the various “Catio” designs provided by the company Catio Spaces. Catio Plans range from $39.95-$69.95 and 10% is donated to animal welfare organizations. See DIY Catio Plans: Catio Spaces also offers free catio tips. Visit www.CatioSpaces.comto learn more.


Diseases transmissible from cats to humans include: Capnocytophaga, Chlamydiosis, ,Leptospirosis, MRSA resistant Staphylococcus aureus, Streptococcus A, Tuberculosis, Pasteurellosis, Plague, Salmonellosis, Yersiniosis, Tularemia, Cat flea typhus, Sporotrichosis, Cat scratch fever,(Bartonellosis) Ringworm ( Dermatophytosis), Malassezia dermatitis, Chaga’s disease (American trypanosomiasis),Giardiosis, Dipylidiasis, Echinococcosis, Larva migrans, visceral, Larva migrans cutaneous, Strongyloides, Acariasis (mange), Rabies.( Ref: The Merck Veterinary Manual, 2010). Cats have infected people with influenza virus and vice-versa.

Cat feces can contain pathogens transmissible to humans and other species, wild and domesticated, be they around farms, in rural, suburban, urban or slum communities. In the latter there may be a trade-off where a lack of sanitation and high rodent numbers are a threat to public health slightly offset by cats’ predation on infective wildlife. See ‘Outdoor fecal deposition by free-roaming cats and attitudes of cat owners and nonowners toward stray pets, wildlife, and water pollution’ by Haydee A. Dabritz, et al Journal of the American Veterinary Medical Association July 1, 2006, Vol. 229, No. 1, Pages 74-81 There are several diseases that can be passed on to humans from cats’ feces, detailed by Cornell University College of Veterinary Medicine:

Toxpoplasmosis is a cat-originating disease. More attention needs to be given to cat-to domestic animal disease transmission as with Toxoplasma in cat feces contaminating farmed animal feed and passing the disease on from infected cattle and sheep in their meat to humans. Cats around zoos also pose a risk of Toxoplasmosis spread to captive wildlife species.

Cat owners, meat eaters and livestock keepers need to take this statement to heart: “Approximately one-third of the world’s human population is seropositive for the apicomplexan protozoan parasite Toxoplasma gondii. Members of the cat family (Felidae) are the only known definitive hosts of T. gondii, yet the parasite can infect all warm-blooded animals as secondary or intermediate hosts [1].

Toxoplasmosis can have a profound impact on human health, not only in terms of congenital disease in infants, severe pathologies in immunocompromised individuals (eg, organ transplant recipients and people with AIDS) [2], and acute, symptomatic infections in adults during outbreaks [3–5], but also through its association with a large burden of behavioral and neurological disorders, including schizophrenia, in immunocompetent individuals [6–9].

Toxoplasma gondii is also of major economic importance for the livestock industry, being responsible for approximately 23% of ovine abortions in Europe and the United States [10].” From the report Toward Improving Interventions Against Toxoplasmosis by Identifying Routes of Transmission Using Sporozoite-specific Serological Tools by Gregory Milne, Joanne P Webster and Martin Walker Clinical Infectious Diseases, Volume 71, Issue 10, 15 November 2020, Pages e686–e693,

Birds of Prey Infected with Cat Parasite

Scientists Sawsan Ammar et al report in their article, Toxoplasma gondii prevalence in carnivorous wild birds in the eastern United States, (International Journal for Parasitology: Parasites and Wildlife,15: 153-157, 2021) They collected carcasses and tissue samples from ten species of raptor among three states (FL, PA, TN) to determine infection prevalence with Toxoplasma gondii. Overall, 32 of 155 birds (20.6%) tested positive for T. gondii exposure. Birds from the order Strigiformes (3 species) had the highest seroprevalence (75.0%), followed by Falconiformes (5 species; 44.8%), and Ciconiiformes (2 species; 3.8%). Barred Owls (Strix varia) had the highest seroprevalence (77.8%). Although raptors have been considered largely resistant to toxoplasmosis, more research is needed on subclinical disease. Furthermore, the exposure rates of raptors may be useful indicators of environmental contamination with T. gondii. The raptors in this study were likely exposed through consumption of infected prey tissues from other birds, small mammals, or insects.

Some have dismissed these concerns emphasizing that infected cats are only infective for a short time. But in actuality they shed Toxoplasma in the environment ( contaminated food, water and soil) can remain infective for many months. Cats become infected when they kill and consume mice and other small mammals carrying the infective intermediary cysts of Toxoplasma, and when fed infected raw meat. Also, recovered cats no longer shedding this pathogen can succumb to this disease and may start shedding again when this dormant pathogen in their bodies multiplies when the cats are stressed and immunocompromised.

Bartonellosis, commonly called cat scratch fever, is now being recognized as a potentially serious bacterial human disease (causing various inflammatory diseases as of the heart, brain and joints) contracted from cats contaminated with flea feces. This bacterium is harbored by fleas and transmitted in their feces to cats’ claws, skin and oral cavities. (See K Burns Bartonellosis: A zoonosis hidden in plain sight. JAVMA 258:1170-1175, 2021.).

Preventing this disease is not feasible when owned cats are allowed outdoors because they are likely to pick up and bring home fleas. Anti-flea drugs, many putting cats at risk from toxicity, that do not immediately kill on contact but must first be ingested by the fleas from the blood of orally medicated cats are no insurance against Bartonellosis and other flea-borne diseases such as typhus and plague. Humans, infants in particular, while playing on the floor, may accidentally swallow a flea infected with Dipylidium tapeworm larvae and become parasitized.

TULAREMIA: Cats that spend time outdoors may be exposed to ticks or animals carrying Francisella tularensis, which causes tularemia in cats, people and other species. It doesn’t take much bacteria to cause illness, so it’s wise to use a tick preventive and seek veterinary care for animals that show signs of illness such as fever, lethargy or appetite changes and people should watch out for cat bites and scratches, which can pass the pathogen to humans. Full Story: Farm Forum (7/26/22)

Visceral larva migrans (VLM) or toxocariasis is a zoonotic infection usually caused by dog or cat round worms of the Toxocara genus. The eggs passed out in the feces are ingested and then hatch into larvae, which penetrate the intestine and start migrating. Because humans are not the definitive host, the larvae cannot mature, and so continue migrating for months or years.

There are two clinical syndromes of infection: VLM and ocular larval migrans (OLM). The symptoms of VLM are related to the organ invaded, most commonly the liver, lung, (asthma being a common symptom) or other thoracic or abdominal organ. VLM usually affects children <5 years old, often from ingesting Toxocara eggs in free-roaming cats’ feces deposited in sand boxes and other play areas. (Visceral Larva Migrans - an overview | ScienceDirect Topics › medicine-and-dentistry).


People who share a bed with, cuddle and kiss cats and dogs while sick with COVID-19 are more likely to pass the disease to their pets, researchers report in Emerging Infectious Diseases. (1). Lead author Prof. Dorothee Bienzle from the University of Guelph’s pathobiology department said results suggest that cats have a higher rate of COVID-19 infection than dogs, stating to the press “It has to do with how well the virus latches on to the receptor in the cat or dog’s respiratory system,” said Bienzle. The high prevalence of COVID-19 antibodies in cats surprised researchers, she said. “We did not expect quite that many,” she said. “Over half of the cats that live in a household of a person who had COVID had antibodies. That’s very high.”(2)

This timely study confirms what I and others with veterinary, medical and scientific background and understanding of epidemiology and zoonoses advocate: All owned cats should be contained/enclosed and not allowed to go off their owners’ property. This would help prevent local wildlife and stray and feral cats from being infected with the SARS-CoV-2 virus and becoming a public health risk as reservoirs of potential infection for years to come. Also, cats infected by humans with this virus could pass on the infection to people as happened in Thailand. (3).Virologists have established that a cat belonging to a COVID-19 positive family sneezed in the face of a veterinarian testing the cat for this disease. Such cases of cat-to-human transmission are probably rare, and researchers emphasize that people should care for their cats — and perhaps take extra precautions when handling cats that might be infected — and not abandon them.


1.Bienzle D, Rousseau J, Marom D, MacNicol J, et al). Risk Factors for SARS-CoV-2 Infection and Illness in Cats and Dogs1. Emerg Infect Dis. 2022 Jun;28(6):1154-1162. 2022.

2.CTV News (Canada)/The Canadian Press (626)

3.Sila, T Sunghan,J. Laochareonsuk.W et al Suspected Cat-to-Human Transmission of SARS-CoV-2, Thailand, July–September 2021 Emerg. Infect. Dis. 28, 1485–1488 2022

Blood samples from 8% of cats being treated for unrelated conditions at the University of Minnesota veterinary college clinic tested positive for COVID-19 antibodies. (Star Tribune, Science & Health. p.2, July 25th 2021).

These studies underscore the importance of not letting cats roam free because of the possibility of human-infected cats infecting other cats and wildlife and then establishing a reservoir of infection in the community. The first medicine and principle of One Health is prevention. This responsibility needs better coordination between State and Federal agencies responsible respectively for domestic animal health, wildlife management and protection and public health. A lack of coordination is evident in a recent review of programs and policies with regard to cats-at-large, domestic cats being allowed to roam free from their homes or becoming feral as wildlife predators.

Veterinarians in private practice, in contrast to those in public health, may not wish to alienate their clients by insisting them to keep cats indoors and providing educational materials. This money-driven lapse in professional responsibility needs to be rectified along with educating those veterinarians who contend that letting owned cats become indoor-outdoor animal companions is best for their overall health and welfare. For more details see the 2019 American Association of Feline Practitioners report Feline Zoonoses Guidelines available at

Local veterinarians and their State Associations need to engage with community animal control and shelter/rescue organizations to more effectively educate and appropriately legislate responsible care of owned cats who should never be allowed to roam off their care-givers’ property. This is not allowed for owned dogs and the same should be applied for owned cats.

A science based policy for managing free roaming cats by Christopher A. Lepczyk · David C. Dufy · David M. Bird · Michael Calver · Dmitry Cherkassky · Linda Cherkassky · Christopher R. Dickman · David Hunter · David Jessup · Travis Longcore · Scott R. Loss · Kerrie Anne T. Loyd · Peter P. Marra · John M. Marzluf · Reed F. Noss · Daniel Simberlof · Grant C. Sizemore · Stanley A. Temple · Yolanda van HeezikBiol Invasions Abstract:

“ Free-roaming domestic cats (i.e., cats that are owned or unowned and are considered ‘at large’) are globally distributed non-native species that have marked impacts on biodiversity and human health. Despite clear scientific evidence of these impacts, free-roaming cats are either unmanaged or managed using scientifically unsupported and ineffective approaches (e.g., trap-neuter-release [TNR]) in many jurisdictions around the world. A critical first initiative for effective, science-driven management of cats must be broader political and legislative recognition of free-roaming cats as a non-native, invasive species. Designating cats as invasive is important for developing and implementing science-based management plans, which should include efforts to prevent cats from becoming free-roaming, policies focused on responsible pet ownership and banning outdoor cat feeding, and better enforcement of existing laws.”

FROM Dr. Fox’s Animal Doctor syndicated newspaper column, July 2023:

The American Association of Feline Practitioners (AAFP) Position Statement Supports Health and Wellbeing of Free-Roaming Cats

DEAR READERS, If you have been reading this column you will know that I question the humanness, effectiveness in cat population control as well as the harm to wildlife and public health risks of the widespread practice of TNVR: trap, neuter, vaccinate and release, of unadopted cats. This position statement from the AAFP (sent by gives unqualified endorsement of TNVR is a call-out from me calling for all concerned to contact the AAFP to stipulate proper care-feeding, shelter, veterinary care as needed and isolation by enclosure if not in areas inaccessible to other free-roaming cats and wildlife.

BRIDGEWATER, NJ; JUNE 08, 2023 – The American Association of Feline Practitioners (AAFP), the trusted leader in feline health and wellbeing for the veterinary community and cat caregivers, announced a new position statement that addresses the growing complexities of managing free-roaming cats. (This is the full statement is from the AAFP website.)

“The American Association of Feline Practitioners (AAFP) supports the humane management of free-roaming cats. A free-roaming cat is any cat not confined to a house or other type of enclosure; this includes owned cats with outdoor access, owned cats that have become lost outdoors (strays) and unowned neighborhood cats that are often supported by caregivers but are not claimed as personal pets or property. Any of these populations may include cats on a socialization spectrum towards people from friendly to feral.

The AAFP supports the humane management of free-roaming cats with the overarching goals of: ✜ sustained reductions of unowned free-roaming cat populations over time; ✜ improved cat health and wellbeing; ✜ mitigating negative impacts on the environment, wildlife, public health and neighborhoods; and ✜ supporting free-roaming cat caregivers and their human-animal bond.

The AAFP supports reducing the number of free-roaming cats through humane capture, sterilization and appropriate homing based on the spectrum of socialization to people and lifestyle that characterizes Felis catus with adoption into homes, where appropriate, and return to the original or appropriate location (eg, barn, community) once sterilized.1 The AAFP supports non-lethal programs for controlling free-roaming populations. Outdoor access for companion cats should focus on methods that address the goals listed above, including leash-walking and fenced yards or other enclosures when possible.2

The AAFP recognizes that the management of free-roaming cats is complex. The AAFP encourages collaboration between humane groups, conservationists, animal control authorities, caregivers and other stakeholders. The AAFP encourages more interdisciplinary research to increase evidence-based management practices.

References 1. International Cat Care. Cat friendly decision-making: managing cat populations based on an understanding of cat lifestyle and population dynamics. (2022, accessed 21 April 2023). 2. American Association of Feline Practitioners. 2016 Impact of lifestyle choice on the companion cat - indoor vs. outdoor. (2016, accessed 21 April 2023).”

I sent this email on June 9th 2023 to Jeff Pane, Marketing and Communications Manager, AAFP: I appreciate you sending me this posting. I have looked over the new statement that condones trap, neuter, vaccinate and release (TNVR) of feral and unadoptable cats but find no details as to how such colonies should be cared for by those involved. Should they be fed? Should they be restricted to contained areas to protect wildlife? What reference citations support the implicit belief of the AAFP that TNVR reduces overall cat numbers in various communities? I would like answers at your earliest to post in my nationally syndicated Animal Doctor weekly newspaper column.

J.P. Replies: The AAFP does not currently have a Position Statement developed on how cat colonies should be cared for; as noted in the Statement – “The AAFP recognizes that the management of free-roaming cats is complex. The AAFP encourages collaboration between humane groups, conservationists, animal control authorities, caregivers and other stakeholders. The AAFP encourages more interdisciplinary research to increase evidence-based management practices.” However, in the Position Statement there is a link to the International Cat Care’s resource – Cat Friendly decision-making: Managing cat populations based on an understanding of cat lifestyle and population dynamics.

My Response: All involved and concerned should consider the excellent advice and initiatives posted by International Cat Care ( website referenced above) and to involve the AAFP in reaching out to make TNVR more than a slow death sentence and life of suffering for unadopted cats being released in many communities across the U.S., harming wildlife and putting public health at risk as I document on my website www.drfoxonehealth .com. It is surely incumbent upon the AAFP to develop a Position Statement on how cat colonies should be cared for.

There is no “freedom” for the domestic cat in having to live as a predator, killing in order to survive.


A single injection of an experimental gene therapy that spurs production of anti-Mullerian hormone (AMH) prevented pregnancy in six female cats in a study published in Nature Communications. (Vansant, L.M., Meinsohn, M.C., Godin, P. et al. Durable contraception in the female domestic cat using viral-vectored delivery of a feline anti-Müllerian hormone transgene. Nat Commun 14, 3140 (2023). If proven safe and effective in larger studies, the gene therapy could offer a nonsurgical alternative for controlling feral cat and dog populations, particularly in under-resourced regions, and reproductive biologist David Pepin is also studying AMH as a human contraceptive. Six of the cats who received a single intramuscular injection of a AMH that prevents ovulation by curtailing the growth process of ovarian follicles, over a two-year follow-up period none of the six that received the gene therapy shot became pregnant.