Inhumane Society Revisited: Outdoor Cats, Wildlife & Human Health

By Dr. Michael W. Fox & Deanna L. Krantz


In essence, cat TNR (trap-neuter-vaccinate (against rabies) and release) programs are good in theory only: The theory being that over time the cat population will decline. With rare exception in small, isolated populations where there is no incursion of non-neutered cats, this is possible. But in reality, with people allowing their un-neutered cats to roam free or escaping from their homes and getting lost and an elusive population of feral, breeding cats that are extremely difficult to trap, most community condoned cat TNR programs, no matter how well intended, are a total failure. Many TNR cats suffer from injuries and diseases, some 36 of which are transmissible to humans and to other cats and to some wildlife species such as Lynx and endangered Florida Panther. Even when there are volunteers feeding them, they will kill birds and small mammals and compete with indigenous carnivores (raptors, foxes, bobcats etc ) for prey. Also, food put out for them can be taken by un-neutered stray and feral cats help fuel the feline population growth.

Predation, where one animal kills another for food, is a natural biological activity and ecological role of indigenous carnivores. Non-indigenous predators, notably the domestic cat, are one of several invasive species that need to be controlled to help protect and restore bioregional biodiversity, ecosystem health and associated public health.

Municipalities would do a better service for cats' well-being, for wildlife protection and for public health by educating and legislating responsible cat care, including microchipping for identification; how to make life indoors a safe and enriching experience for cats; establishing closed colonies of neutered cats for group housing by local animal shelters and cat lovers united. The "No Kill" animal shelter movement should not mean that cats considered to be unadoptable are neutered and released into our communities. We would not do this to dogs and such cats should not be victim of the misguided sentiment of the advocates of TNR.

The stress, health and behavioral problems of indoor cats disturbed by cats prowling, yowling and spraying around their homes are well documented. Some are euthanized when they begin to spray in the home or become aggressive, or are put on psychotropic medications. So it is inconsiderate and highly irresponsible for cat owners to allow their cats to roam free off their properties and calls for legislation to mandate cats being kept on their owners' property.

Many advocates of trapping, neutering, vaccinating and releasing cats (TNR) claim that this saves these cats’ lives because they are too wild to be adopted and would otherwise be euthanized. They go on to argue that these cats adapt and find their place in the environments/ecologies where they are released. They also contend that cats play a vital role in controlling rodents that can carry diseases harmful to people, such as the plague or Black Death that in the mid -1300s wiped out one-third of Europe’s population.

This deep scar on the human psyche, passed on from generation to generation is one of the justifications used to rationalize releasing cats as “working cats” into our communities for our health’s sake to control “vermin” (Rats adjust behavior to evade cats). Cats kill very few rats because rats adjust their behavior and spend more time in their burrows to avoid becoming prey, researchers reported in Frontiers in Ecology and Evolution. The researchers used motion-sensing cameras and microchips to track rats' behavior in response to the presence of cats. United Press International (9/27/18).

Another justification, according to one (pro-life?) advocate of the “No Kill” animal shelter movement is that “We really need outdoor cats because in most places there are no natural predators to control wildlife.” Yet we have owls, hawks, red foxes and coyotes in our neighborhood, now competing with TNR cats released by our local humane society to fend for themselves through Minnesota’s harsh winters. Many may become food for coyotes.

This same No Kill advocate also asserted that “These cats killing birds like sparrows and starlings that were introduced here from Europe will help native birds recover.” Does this mean cats know the difference in their catch-as-catch can survival mode between native and non-native species?

Outdoor cats compete with wild predators such as foxes and hawks for the same prey while feeding outdoor cats attracts raccoons & other wildlife. Photos all in same location by the authors.

Cats were once blamed for causing the plague and were exterminated in several European communities, yet this did not stop the plague’s spread just as their presence made no significant difference in stemming the pandemic and pandemonium. TNR cats are not likely to help prevent a potential pandemic disease like the Black Death because many cats are not efficient rat killers and prefer to kill and consume smaller rodents and song and ground-nesting birds, reptiles and insects. And, more significantly, the Black Death, the plague caused by Yersinia pestis, most probably came not from infective rat fleas but from human fleas and lice transmitting the disease from person to person, rats and cats having little if any involvement.

Cats can get the plague and potentially carry infective fleas from rats (and rabbits), to humans, especially if they are indoor-outdoor cats. Would a colony of TNR cats really play any significant beneficial public health service in any community this regard, or actually pose public health concerns from other diseases transmissible to humans* such as rabies, visceral larva migrans, toxoplasmosis and giardiosis? Indoor-outdoor and feral cats can also harbor ticks which can cause Lyme disease, babesiosis and other potentially fatal human diseases. Cats can certainly help control rodents around grain and feed storage areas but there are none in most places where TNR cats are being released, including the suburban residential community of Golden Valley, MN where the authors live and where wildlife are at risk from outdoor cats. Also domestic cats can infect Bobcats and Cougars with lethal viruses as reported in dead and dying Florida panthers, an endangered species.

Advocates of TNR and organizations like The Animal Humane Society (AHS) in Minneapolis which calls its TNR program a Community Cat program of “RTF” (Return to Field) also insist that releasing vaccinated and neutered cats helps reduce the cat population by keeping other cats in the surrounding area away from where the TNR cats are being released. There is no scientific evidence to support this hypothesis beyond relatively isolated sites like a barn or college campus. With massive cat-catching drives coordinated municipality by municipality, suburban community by community, city-block-by-city-block and industrial “park” office and warehouse complex-by-complex and releasing large numbers of neutered cats close around the same time (otherwise resident cats will simply relocate and become a multiplying problem elsewhere) this would obviously mean fewer cats being born in a given area. Also problematic is that these RTF cats are not tested and treated for parasites which could be a public health risk and are not tested for feline leukemia and immunodeficiency virus infections which, along with several other diseases could put other cats at risk.

There are no large-scale inter-municipal efforts in most parts of the U.S. today to deal with the feral and cats-at-large issue and failure is inevitable without cat-owner education and strict enforcement of laws prohibiting owned and non-neutered cats being allowed to roam free and breed. Regardless, many cat owners are firm in their belief that their cats do best as indoor-outdoor animals. It is a long-standing cultural tradition which must be changed because of the relentless increases in human and cat populations. This erroneous belief as self-serving and harmful as the unconditional advocacy of TNR which causes much suffering, probably worse than death, for those poor “unadoptable” cats caught up in their own plague and an inhumane society acceptance of outdoor cat exploitation and cruelty. (For earlier examples see Inhumane Society: The American Way of Exploiting Animals by Dr. Michael W. Fox. St. Martin’s Press NY 1990). All TNR programs, releasing cats to roam outside of an enclosed area (wherein they should receive proper care) violate the animal health and welfare, environmental and wildlife protection and public health mandates of bioethics and One Health policy and praxis**.

One Minnesota Animal Humane Society (AHS) staffer informed us that “people in your neighborhood feed our Community Cats who help reduce the cat population where you live” but declined to tell us who does the regular feeding and inspection. Another staff member said there was no such feeding. These cats are regarded as “wild animals” by the AHS and local police dept. yet the MN Dept. of Natural Resources discourages people from feeding wildlife and some municipalities have ordinances prohibiting the feeding and encouragement of wildlife. Certainly, putting food out for free-roaming, feral and TNR “Community Cats” will attract raccoons, opossums and other indigenous wildlife and provide a food-source of cats for increasingly omni-present coyotes.

Outdoor cats are predators especially of song birds and small mammals

Outdoor cats are prey for coyotes now expanding into urban, suburban & rural communities across the U.S.

As a veterinarian and former Scientific Advisor and Vice President of the Humane Society of the United States (HSUS) in Washington DC co-author Fox always opposed TNR on humane grounds for those cats evaluated as “unadoptable” where the alternatives of group-housing in enclosed colonies is preferable, as per those of Pro Animale in Europe, and if not available, then euthanasia for humane, public health and wildlife protection reasons. As we have learned from personal experience, many such cats are amenable to human socialization and testing cats just caught and taken into a shelter will understandably show defensive-aggressive behavior out of fear. This should not lead to their immediate rejection as “unadoptable” and being released back where they were found. Their recovery/socialization for adoptability takes time and patience, and when in group-housing situations they will often lose their fear and come to trust people especially when they see other cats in the enclosed colony enjoying human contact and displaying affection.

Multi-level, indoor-outdoor group housing for stray cats, Pro Animale für Tiere in Not e.V.

Many cities across the U.S. are embracing TNR under the endorsement of the HSUS which should be held accountable for advocating one of the most inhumane practices of the 21st century. We are appalled that the HSUS actually endorses and promotes TNR which we consider antithetical to the mission and ethics of animal welfare and protection organizations and which we see as pandering to the pro-life-no-kill sentiment sweeping the country and as self-serving, not wanting to lose donors who love cats and who believe TNR programs are the best solution to what many biologists regard as a plague of free-roaming cats. No TNR program can be effective in communities where people with cats do not have them neutered and allow them to roam free off their properties---and breed, kill wildlife, and get killed, injured or diseased. Even if some TNR cat “colonies” are being regularly fed, cats will still kill, and any becoming sick or injured cannot be provided adequate veterinary treatments.

Much needed veterinary care was delayed in this long- suffering free-roaming cat until she was so weak she was easily caught but had to be euthanized.

Certainly in relatively closed rural communities and poor urban neighborhoods in the U.S. and abroad where there are large populations of cats outdoors, TNR is one tool to help control their numbers as with village dogs in India and Africa where we have worked. But the public health risks from cats carrying zoonotic diseases from rabies to Toxocariasis ( see Addenda below) and the lack of veterinary preventive medicine and disease surveillance in such communities is problematic.

Cats and raccoons together sharing food at TNR cat feeding station. Excellent opportunity to share pathogens. Raccoons are one of the reservoir hosts of the Rabies virus; they also spread Leptospirosis, Canine distemper, roundworms, fleas, and ticks.

According to the LEAGUE OF MINNESOTA CITIES INFORMATION MEMO Animal Regulation in Cities:

VI. Regulation of cats Section IV, Animal regulation – general information. In addition to the general requirements already discussed earlier in this memo, cities may impose requirements for care of cats by ordinance. “Outdoor Cats: Frequently Asked Questions,” Humane Society of the United States. Often the most problematic cats in the city are feral cats. Feral cats are from the offspring of lost or abandoned pet cats or other feral cats who are not spayed or neutered. These cats were never pets and do not have owners. (In comparison, stray cats are pet cats that have wandered off or gotten loose). RELEVANT LINKS: League of Minnesota Cities Information Memo: 4/10/2018 Animal Regulation in Cities Page 29 Feral cats are not tame like pet cats and can be difficult to handle. Feral cats can threaten the health, safety, and general welfare of the city. Some of the more common concerns include: • Noise from fighting or mating cats. • Foul odors from cats marking their territory. • Flea infestations. • Multiplying numbers of feral cats. • Visible suffering and death of kittens and cats. Cities may take action to deal with feral cats.

A. Feral cat trapping programs “Outdoor Cats: Frequently Asked Questions,” Humane Society of the United States. If cities choose to take action on the feral cat issue, it is often done by adopting a program. A “Trap-Neuter-Return” program is recommended by the Humane Society of the United States (HSUS). italics ours). At a minimum, this program includes spaying or neutering, giving rabies vaccinations, and surgically ear-tipping. (Ear-tipping is the universally recognized sign of a cat that has gone through this sort of program). The positive results from this program include: • Reduced mating-related fighting and other related noises. • Neutered or spayed feral cats roam much less and are less visible and less prone to injury from cars. • Reduced foul odors (neutered male cats are no longer able to produce the stinky spray used to mark territory). • Reduced reproduction activity leads to fewer feral cats being born, resulting in a lower population over time. Some cities will have city employees trap cats. Other cities will enlist the assistance of the residents in trapping cats. Cities may provide the traps for residents to pick up. Cities can accept feral cats that were trapped by residents and brought to designated spots, such as the animal control authority.

B. Feeding bans “Outdoor Cats: Frequently Asked Questions,” Humane Society of the United States. Sometimes cities will impose “feeding bans” that prohibit residents from feeding feral cats with the idea that if the cats are not fed, they will go away. While this seems like it would work, it often does not. One reason relates to enforcement. Feeding of feral cats is not easily observed behavior so it is not easy to enforce a ban. Further, some people do not like to see animals suffering and will feed the cats despite the ban. Even if people are not intentionally feeding them, feral cats can still find food from other sources like dumpsters and garbage cans. RELEVANT LINKS: League of Minnesota Cities Information Memo: 4/10/2018 Animal Regulation in Cities Page 30 “Outdoor Cats: Frequently Asked Questions,” Humane Society of the United States Feral cats can often survive for weeks without food (italics ours) and, since they are territorial animals, they will not quickly or easily leave their territory to look for new food sources. Instead, they tend to move closer to human activities as they grow hungrier and more desperate. Malnutrition makes them more likely to succumb to parasites, like fleas, that can spread into houses, garages, and businesses. Finally, malnourished cats are likely to continue to reproduce, resulting in malnourished kittens, causing this cycle to continue.

C. Disposition Section III-B, Disposition of animals. Some cities will choose to dispose of feral cats that have been captured instead of spaying or neutering and returning them. If the city chooses this method, it should dispose of these cats in a humane manner. (END)

NOTE: No mention is made about feeding and caring for TNR cats, tending the sick and injured or for re-vaccinating them especially against rabies.

One reader of Fox’s nationally syndicated newspaper column Animal Doctor was an enthusiast of TNR for some years but wrote to us that he eventually gave up in disgust and out of pity for these poor cats, stating:

” Prior to 1990s, TNR was considered illegal and was underground. What Animal Care & Control did regarding stray cats or dogs was rounding them up and having them euthanized (which is the humane thing to do in my opinion). Unfortunately since 1990s, things have gone backwards. TNR has become increasing popular because of the so called “No Kill” movement---- I don’t think TNR people are bad people at all. I did it for 3 and a half years myself. I know the intention of TNR people is good. I know my intention when I did TNR was a loving intention: I just wanted to help those poor cats. Maybe that’s why my philosophy changed over time having witnessed personally what could happen to these outdoor cats: getting hit by cars, getting killed and sliced under car hoods, fleas, ticks, parasites, ear mites, worms, infections, getting shot or poisoned by people, trapped in garages or places they cannot get out, freezing to death or suffer cold related symptoms like hypothermia and losing paws, the list goes on and on. My main issue is once you release them, it is highly unlikely and impractical to help them again when they need medical attention whether they are abandoned back onto the streets, backyards or even farms. Most of these outdoor cats don’t die of a humane death. If they are lucky enough, they get hit by a car and die instantly. But many times they likely die of a slow and agonizing death from diseases, infections etc. I think we live in a death fearing and death denying society. I think the issue with the “No Kill” movement falls under that umbrella. I think No kill shelters are horrible because once they are full, they turn away animals. Some people then just simply abandon their animals on the streets, in the woods, and sometimes even leave them behind in the homes after they are evicted. To me “No Kill” people lack a level of empathy because they operate from an ideological purity perspective, rather than from an empathy perspective for the animals such as feral cats. The reason I have the perspective I do is because I put myself in the feral cats’ perspective and all the struggles they to go through to get their basic needs met, food, water, shelter and medical care etc. To me the situation is clear: feral cats have a hard, short and suffering life on the street. If I can help them by bringing them indoors, I will do that. If I’m not able to, at least I could help end their suffering through euthanasia.”

(email from Paul Zhang, May 1/18).

Veterinarians in the U.S. and U.K. have been recently discussing managing “moral distress” in companion animal practice. Certainly emotional distress coupled with the moral dilemma of euthanizing healthy but temperamentally unadoptable cats ( and even dogs considered dangerous who can end up incarcerated their entire lives in No Kill shelters) is a professional challenge but should not lead to the unconditional endorsement of TNR as an alternative to ending the lives of cats humanely rather than opting ( for emotional rather than bioethical reasons) to neuter and vaccinate them and release them to fend for themselves outdoors. The same must be said about those many people who support TNR, putting their own emotion-governed values and beliefs over the emotional and physical well-being of the cats for whom they claim to love.

Peoples’ indoor-outdoor cats and TNR cats can affect indoor cats who see, hear and smell them around their homes. This can cause indoor cats to become un-housebroken, to spray, develop stress-related diseases such as cystitis, aggravate other common conditions such as diabetes and thyroid disease and trigger redirected aggression toward other cats and people in their homes.

The domestic cat deserves our respect and empathy and should not fall victim to the misguided, feel-good sympathy of home-owners feeding stray cats at their doorsteps and animal rescue/ sheltering “humane” societies setting neutered ones back into our communities all under the questionable authority and unqualified encouragement of the Humane Society of the United States. State veterinary, public health* and wildlife conservation and management authorities and organizations need to address this serious issue without further delay for the good of all.

Dr John Read | Wildlife Ecologist interview MAR 2020 · AUSSIE WILDLIFE SHOW on the threat of free ranging cats in Australia and cat control methods restoring ecological balance. Talks about the threat to humans -details toxoplasmosis. His book "Among the Pigeons, Why Cats Belong Inside" advocates for keeping pet cats indoors with a chapter on how TNR is ineffective.

Preventing Toxoplasmosis From Infceted Meat and Infective Cats

Cat owners and 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,

Essentially, handle meat with care and cook well if you must eat it and keep cats indoors so they do not pick up this parasite from prey they kill and eat, and especially if you are pregnant or immunocompromised, have someone else clean out the cat litter box especially if you still have an indoor-outdoor cat.

MAKING CATS SAFE from 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

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 to learn more.

Prefabricated cat enclosures marketed in the U.S. by Catio Spaces

Neck-bib better than a bell to stop bird catching & killing in enclosed yard. Indoor-outdoor cage accessible from inside the home with climbing and resting areas off-ground and top covered with sheltered area provided by U.K. home owner.

Indoor enriched environment and outdoor “catio” for group-housed rescued “feral” cats with 85% socialization recovery and adoptions Faribault, MN



Dr. Arie Trouwborst, of Tilburg University in the Netherlands, recently presented "Domestic Cats and International Wildlife Law" as part of a biodiversity lecture series for the Stetson University Law School. Dr. Trouwborst's research (Trouwborst and Somsen 2019; Trouwborst et al. 2020) has led him to conclude that stray and feral cats must be "removed or controlled when they pose a threat to protected species and/or sites" and that owned cats should be kept under their owner's control. CLICK HERE to watch Dr. Trouwborst's presentation.


The City of Saratoga Springs, Utah, conducted an analysis on "The Science of Feral Cats" to help it understand and effectively address feral cat issues in the community. The report was initiated after Best Friends Animal Society called on the City to implement a trap, neuter, release (TNR) program. This extensive report (100 pages) found that "overwhelmingly, science does not support TNR programs as an effective method to reduce feral cat populations" and that such programs "fail to adequately mitigate the significant threat to public health or alleviate the negative impacts on wildlife that feral and free-roaming cats pose." CLICK HERE to read the full report.

In a report entitled ‘Further discussion on declining wild bird populations and feral cats’ published in the Journal of the American Veterinary Medical Association ( Vol. 257: p 144-145, 2020), veterinarians David A. Jessup and Sonia M. Hernandez provide documented support for their contention that “the link between free-roaming cats and bird deaths is clear and that TNR programs, as typically structured, do not reduce free-roaming cat populations.” They assert “TNR programs alone seldom, if ever, result in feral cat colony reduction or elimination and that removal for adoption or euthanasia is needed to bring the number of feral cats down.”

They advocate that those choosing to care for feral and free-roaming cats set up large enclosures-mega-“catios” (with provision of shelter, food, water and veterinary care) to protect both wildlife, public health and the cats themselves.


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

This study notes: The cat population in Cayucos, Los Osos, and Morro Bay, Calif was estimated at 7,284 owned and 2,046 feral cats, and 38% of surveyed households owned a mean of 1.9 cats/household. Forty-four percent of cats defecated outside >75% of the time. Annual fecal deposition (wet weight) by owned cats in the 3 communities was estimated to be 77.6 tonnes (76.4 tons). Cat owners were more likely to oppose cat licensing and impounding stray cats and support trap-neuter-return for stray cats and less likely to be concerned about water pollution, than were non-cat owners.

Conclusions and Clinical Relevance—Feral cats represented a sizeable proportion (22%) of the free roaming cats in this area and could be contributing 30.0 tonnes (29.5 tons) of feces to the environment per year. However, feral cats are not the principal source of fecal loading because owned cats defecating outdoors contribute an estimated 77.6 tonnes (76.4 tons) or 72% of the annual outdoor fecal deposition.

There are several not uncommon diseases that can be passed on to humans from cats’ feces, detailed by Cornell University College of Veterinary Medicine:

“ Salmonella poisoning, also called salmonellosis, is caused by a group of bacteria called Salmonella, and can lead to diarrhea, fever, and stomach pain. It is possible to contract the disease from infected cats, which can carry Salmonella bacteria and pass them in their stool. Although salmonellosis usually resolves on its own, some individuals require medical attention to address severe diarrhea or the effects of the infection on organs other than the digestive tract.

Salmonella is more commonly found in cats that feed on raw meat or wild birds and animals, so owners can reduce the risk of salmonellosis in themselves and their cats by keeping cats indoors (italics mine) and feeding them cooked or commercially processed food. Wearing gloves when cleaning litterboxes or gardening (in case outdoor cats have defecated in the soil) and washing hands thoroughly after these activities is also recommended.

Certain feline intestinal parasites, including roundworms (Toxocara) and hookworms (Ancylostoma), can also cause disease in people. Children are particularly at risk due to their higher likelihood of contact with soil that has been contaminated by cat feces. Although most people infected with feline intestinal parasites do not show signs of illness, some people may get sick. Visceral larva migrans, a potentially serious disease that can affect various organs, results from consumption of Toxocara eggs (for instance, when soiled fingers are placed in the mouth). Toxocara larvae may then migrate to abdominal organs, including the liver, or to the central nervous system. Symptoms of visceral larva migrans may include fever, fatigue, coughing, wheezing, and abdominal pain. Ocular larva migrans is the term used for a condition in which Toxocara larvae migrate to the eye, causing visual disturbances, abnormal eye movements, or eye pain and discomfort.

In their research publication (PLoS Negl Trop Dis. 2014 Aug; 8(8): e3116.)

Toxocariasis in North America: A Systematic Review, Rachel M. Lee et al state:

“Toxocariasis is an important neglected tropical disease that can manifest as visceral or ocular larva migrans, or covert toxocariasis. All three forms pose a public health problem and cause significant morbidity in areas of high prevalence. To determine the burden of toxocariasis in North America, we conducted a systematic review of the literature following PRISMA guidelines. We found 18 articles with original prevalence, incidence, or case data for toxocariasis. Prevalence estimates ranged from 0.6% in a Canadian Inuit community to 30.8% in Mexican children with asthma. Commonly cited risk factors included: African-American race, poverty, male sex, and pet ownership or environmental contamination by animal feces.”

Free-roaming, foraging dogs and cats are the main source of this global parasitic disease. These authors conclude: “Further research is needed to determine the true current burden of toxocariasis in North America; however the prevalence estimates gathered in this review suggest that the burden of disease is significant”.

According to the U.S. Centers for Disease Control and Prevention “A U.S. study in 1996 showed that 30% of dogs younger than 6 months deposit Toxocara eggs in their feces; other studies have shown that almost all puppies are born already infected with Toxocara canis. Research also suggests that 25% of all cats are infected with Toxocara cati. Infection rates are higher for dogs and cats that are left outside and allowed to eat other animals. In humans, it has been found that 5% of the U.S. population has been infected with Toxocara. Globally, toxocariasis is found in many countries, and prevalence rates can reach as high as 40% or more in parts of the world. There are several factors that have been associated with higher rates of infection with Toxocara. People are more likely to be infected with Toxocara if they own a dog. Children and adolescents under the age of 20 are more likely to test positive for Toxocara infection than adults. This may be because children are more likely to eat dirt and play in outdoor environments, such as sandboxes, where dog and cat feces can be found. This infection is more common in people living in poverty. Geographic location plays a role as well, because Toxocara is more prevalent in hot, humid regions where eggs are able to survive better in the soil” ------

Cutaneous larva migrans, an itchy skin disease, is caused by contact with soil contaminated with Ancylostoma larvae. These larvae may penetrate and migrate under the skin, with resultant inflammation, itching and pain, and raised, red linear lesions in the skin that follow the larva’s migration. Proper hygiene, including washing hands before meals, cleaning soil from vegetables, and reducing exposure to cat feces can prevent infection”.

It is uncertain whether species of Giardia that infect cats are contagious to humans or vice versa, although recent studies suggest the possibility of cat to human transmission. Careful hygiene will eliminate the risk of accidental ingestion of cysts.

Toxoplasma ( From ) Toxoplasmosis can be transmitted to humans, although most otherwise healthy people infected with this organism show few if any signs of disease. The exceptions to this are immunocompromised individuals and pregnant women, both of whom should be very careful to avoid exposure to infective Toxoplasma oocysts (see our article on Zoonotic Diseases).---

---The Centers for Disease Control and Prevention (CDC) has recently identified toxoplasmosis as one of five neglected parasitic infections of people due to its high prevalence. More than 60 million people in the U.S. are thought to be infected.

Cat owners and 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,

Reducing the incidence of toxoplasmosis in cats requires measures to reduce both exposure to infective oocysts and shedding of oocysts into the environment. Cats should preferably be fed commercially prepared, cooked foods (appropriate heating inactivates any T. gondii cysts that may be present) and should not be allowed to eat uncooked meat or intermediate hosts, such as rodents. They should also be denied access to facilities housing food-producing livestock and food storage areas.

Because cats only shed the organism for a short time, the chance of human exposure via cats they live with is relatively small. Owning a cat does not mean you will be infected with Toxoplasma. Since it takes a minimum of 24 hours for T. gondii oocysts in cat feces to sporulate and become infective, frequent removal of feces from the litter box, while wearing gloves and washing hands afterward, minimizes the possibility of infection.--- Indoor cats that do not hunt prey or consume raw meat are unlikely to be infected with T. gondii. In the U.S., people are much more likely to become infected by eating raw meat and unwashed fruits and vegetables than by handling cat feces. The possibility of infection after gardening in soil that has been contaminated with cat feces also exists, and this possibility can be mitigated by wearing gloves and by washing hands after gardening.

Pregnant women and immunodeficient individuals are the two populations most at risk of developing health problems after T. gondii exposure. In utero infection is of the greatest concern in humans. Between one-third and one-half of infants born to mothers who acquired Toxoplasma during pregnancy are infected. The vast majority of women infected during pregnancy have no symptoms themselves, and the majority of infected infants will show no symptoms of toxoplasmosis at birth. Many of these children, however, are likely to develop signs of infection later in life, including loss of vision and hearing, mental retardation, and, in severe cases, death.

In people who are either undergoing immunosuppressive therapy or have an immunosuppressive disease such as acquired immunodeficiency syndrome (AIDS), toxoplasmosis may cause enlargement of the lymph nodes, eye and central nervous system disturbances, respiratory disease, and heart disease. In these patients, especially those with AIDS, relapses of the disease are common, and the mortality rate is high”.


For further reading see:

Maybe Rats Aren't to Blame for the Black Death - National Geographic.

Anne Fawcett & Siobhan Mullan,2018, Managing moral distress in practice, Veterinary Record, In Practice, 40: 34-46

Why I Am Against Trap Neuter/Spay Release (TNR) For Feral Cats

For details visit Trap, Neuter, Release - American Bird Conservancy Trap, Neuter, Release (TNR) is advertised as a tool to reduce feral cat numbers. Unfortunately, TNR programs have been shown to fail to reduce feral cat numbers….

Risk of parasitic infections is high in indoor-outdoor cats

Peter Marra & Chris Santella, Cat Wars: The Devastating Consequences of a Cuddly Killer. Princeton University Press 2016

Chalkowski K., A.E. Wilson, C.A. Lepczyk, and S. Zohdy. 2019. Who let the cats out? A global meta-analysis on risk of parasitic infection in indoor versus outdoor domestic cats (Felis catus). Biology Letters 15: 20180840. doi: 10.1098/rsbl.2018.0840. Domestic cats that spend time outdoors are nearly three times more likely than their indoor-only counterparts to contract parasitic infections, including some that can infect people and other animals, according to a meta-analysis published in Biology Letters.( 19 different pathogens including many relevant to human, domestic animal and wildlife health, such as Toxoplasma gondii and Toxocara cati.). The researchers also found that cats in higher geographic latitudes have a greater risk of picking up parasitic infections. - Trap-Neuter-Release is not a humane or effective solution for feral cats. TNE-Trap, Neuter, Enclose is the ethical and humane altenative.

Includes United States Department of the Interior /FISH AND WILDLIFE SERVICE letter in support of NJ ban of TNR, with the statement that US Fish and Wildlife Service considers "all domestic and feral cats (a non-native and invasive predator)"

Legal standing re the relevancy of the Endangered Species Act

FWS "Supports efforts of volunteers or organizations that trap and neuter free-ranging cats, but require that animals be adopted and kept indoors or be released into managed areas that are appropriately fenced or otherwise enclosed to prevent animals from roaming outside of a contained space."

Also includes: SAMPLE PETITION: We, the undersigned, are opposed to Ordinances that permit Feral Cat Colony Management, also known as Trap-Neuter-Release or Trap-Neuter-Return or TNR or Community Cat Management.

**See M.W. Fox Healing Animals & the Vision of One Health. Create Space Books, 2011.

The authors live in Golden Valley, MN. Krantz was formerly acting director of investigations and law enforcement at the ASPCA, New York and Fox is a veterinarian and former Vice President of the Humane Society of the U.S. Washington DC.


Photo montage of “Mr. Sammler” trapped on our property in Golden Valley MN by Fox & Krantz, * Dec.27, 2015-March 7, 2016. First seen in the summer, eventually trapped, neutered, tested for feline immunodeficiency and feline leukemia virus, treated for round and tape worms and fully vaccinated. Estimated 18 months old. Gradually acclimated to us and resident ex-feral cat who served as a socializing catalyst.

Summer night hunter, then caught in trap (portrait through the wires) then in-house holding cage meeting resident ex-feral cat

Tentative social interaction begins 2 weeks after release from crate, kept open in cat’s “safe” room.

Secure in cubby-hole, after 2 weeks accepts being touched and later, paw massage; plays with feathers on a cane under rug

Submits to resident cat, bonds looking outdoors at bird feeders and sleeping together; after 4 weeks enjoys interactive play and stroking with feather-cane and plays under carpet with feather cane and resident cat

Mr Sammler, 8 weeks into recovery; a magnificent Silver tabby landrace, adapting well to life indoors

Mr. Sammler’s eye talk: Surprise and curiosity, fear and insecurity, trust and acceptance

The authors, Dr. Michael W. Fox and Deanna L .Krantz can be reached at Website