What is Trap-Neuter-Return (TNR)?

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Trap-neuter-return (TNR) is the process of humanely trapping community cats, sterilizing them, and then returning them to the location where they were caught. TNR is also sometimes called trap-neuter-release, trap-neuter-vaccinate-return (TNVR), and trap-neuter-return-monitor (TNRM).

The accepted method of free-roaming cat control has been to take lethal measures. Animal control has used trap-and-kill methods for over a hundred years (1, 5, 9). In addition to being horrible, it clearly has not worked. Community cats didn’t disappear or even diminish as a result. This is due to the vacuum effect.

The vacuum effect happens when animals are removed from an environment, but the resources in the environment stay the same (3, 5). The remaining animals of the species will either breed until they reach the environment’s capacity again, or animals from elsewhere will migrate to the area, or both (1, 3, 5, 9, 11). In the end, no matter how many community cats animal control departments have euthanized, the population has always recovered. TNR was created as a solution that is humane and, while it takes time, ultimately effective.

How Does TNR Work?

The goal of TNR is to reduce community cat populations over time with the least possible harm to individual cats. Ideally, the cats ultimately benefit. Cats are trapped in box traps, which are designed to not cause injury, and taken to a veterinarian. How much care they receive at the clinic depends on who is doing the TNR, but at minimum the cat is sterilized. Rabies vaccines are pretty standard (1-3, 5, 9). A variety of other vaccinations are sometimes given as well. The cats are examined, and any health issues or injuries are treated.

During the spay/neuter surgery, veterinarians often mark community cats so that others can tell they are sterilized. This prevents the cats from the unnecessary stress of being captured and possibly operated on again (3, 6, 13). Eartipping is a common method of marking sterilized community cats. Eartipping means the vet removes the top quarter inch of a cat’s ear, usually the left ear, during the surgery (2, 3, 6). It doesn’t harm the cat, and it is clearly visible even from some distance. Alternatively, vets may put a small tattoo on the abdomen (12, 13) or a v-shaped notch in the side of the ear.

After cats recover from their surgery, they are returned to the site where they were captured so that they can resume their lives without making any more kittens. A caregiver may feed and keep an eye on the community cats, but they will continue to live mostly apart from humans and be happy to do so. Not all community cats are feral, however, so not every cat that is trapped in a TNR program will be returned. Kittens and friendly adults go to the clinic like the others, but then they are adopted out (1, 5, 9). Kittens should be left with their mothers until they are weaned if at all possible.

Advantages of TNR

…For the Cats

Sterilizing community cats has big benefits for their health. She-cats are spared the physical stress and dangers of repeated pregnancies (1, 5). Cats of both sexes have drastically lower risks of reproductive cancers (1, 3). Research has demonstrated that sterilized community cats gain weight and live longer lives, too (1, 3, 5). A study at the University of Florida found that 83% of the cats in TNR-managed colonies on campus had been in the colony for at least six years (1, 5, 7).

Without the drive to mate, cats fight less and don’t wander as far, so they suffer fewer injuries (1, 3, 5). And while a single dose of a vaccine usually doesn’t last forever, the vaccination(s) cats receive through TNR are more protection than they would have otherwise had from infectious diseases (1).

…For the Community

Some people are really not happy to share their space with community cats. Fortunately, sterilized cats make better neighbors. They don’t yowl, fight, and spray nearly as much as intact cats do, and this can take care of a lot of peoples’ complaints with them (1, 3, 5, 8, 9, 11). Any problems that continue will dwindle over time as the community cat population shrinks.

Fewer community cats and fewer complaints about them leads to lower rates of shelter admission (1, 5, 8, 9-11, 13). San Jose, California Animal Control reported a decrease of 29.1% in their intake of cats and kittens after fours years of a citywide TNR program (6). Albuquerque, New Mexico saw a decrease of 43.5% in three years (6). This decreases the number of cats euthanized in shelters (1, 9-11). Many community cats that enter shelters are euthanized because they are not adoptable. About half of shelter workers who have to euthanize animals develop post-traumatic stress disorder (13). Not euthanizing healthy animals is better for everyone.

Fewer cats in the shelters also decreases their operating costs (1). But shelters are not the only ones that can save money as a result of TNR. The outdated catch-and-kill strategy hemorrhages taxpayer dollars to little or no effect (1, 5). As previously discussed, it just doesn’t work, but it does cost money. In the words of Mark Kumpf, former president of the National Animal Control Association, “The cost for picking up and simply euthanizing and disposing of animals is horrendous, in both the philosophical and the economic sense” (5).

The extent of the monetary cost depends on the animal control department. Similarly, how much can be saved depends on the TNR program and how it is run. In general, TNR programs appeal to volunteers and get progressively less labor-intensive over time (5). Any TNR program will save money that way.

Does It Really Work?

Research has demonstrated that TNR can, in fact, do all that is aims to, in a variety of communities at that. I’ve thrown some statistics at you already, but here’s a few more:

• A TNR program that began in Newburyport, Massachuchetts in 1992 with about 300 cats essentially ended 17 years later when there were no cats left on the waterfront. The last cat, Zorro, died in December of 2009 at an estimated age of 16. No community cats have been seen at the waterfront since [as of interview date]. (10)
• An 11-year study at the University of Florida observed community cats on campus. At the end of the study, the population had decreased by 66% and no new kittens had been seen since the fifth year. (7)
• A Florida study conducted TNR for two years in one zip code, and then compared shelter intake from that zip code to the rest of the county. At the end of the study period, the shelters where there had not been any TNR had 3.5 times more cats admitted and 17.5 times more euthanized. (8).
• A study of TNR efforts in Chicago, Illinois found that the average reduction in colony population was 54% over nine years. This was right after the city of Chicago changed its stance to support TNR. (11)
• The University of New South Wales in Sydney, Australia, began a TNR campaign on campus in August, 2008. By September, 2017, the cat population had been reduced by 78%, and the 15 remaining cats were all sterilized. (12)
• A survey of Australian TNR participants found that a median 69% of the cats in respondents’ colonies were sterilized. The median reduction in colony size was 31% over a median of 2.2 years of TNR. (13)

Criticisms of TNR

That was just a sampling of the studies supporting TNR. There have been a couple which studied a location where TNR was not successful, but the vast majority have given the method the thumbs-up. Many organizations champion TNR, including the American Society for the Protection of Animals, Humane Society of the United States, Association of Shelter Veterinarians, and American Association of Feline Practitioners. But TNR does have its opponents.

Many of these opponents are conservationists. They are opposed to returning community cats to their territories because community cats hunt endangered birds and other wildlife (2, 4, 6). And that’s true, cats do hunt wildlife, and they are essentially an invasive species. As a domestic animal, they really have no natural habitat, although they may sometimes be considered naturalized in an environment. However, cats are far from the biggest threat to at-risk wildlife. Habitat loss is considered the worst offender by a wide margin (5, 6). Additionally, TNR is effective at reducing the population of community cats, so fewer birds and other prey animals will be hunted in future (5, 6).

Another concern is disease. Community cats can carry diseases that pet cats, humans, or other animals could catch, such as rabies and toxoplasmosis (2, 5, 6). This is certainly possible, but the Centers for Disease Control say that humans are very unlikely to get a disease from a cat (5, 6). The CDC reports only two cases of rabies transmitted from cat to human since 1960, and tells us that we would be more likely to get toxoplasmosis from eating raw meat or even gardening (5, 6). Pet cats or other animals are more at risk. However, TNR programs that vaccinate cats for common illnesses and treat them for any parasites they already have can go a long way toward reducing the disease burden in the community cat population.

Some claim that it is not humane to return community cats to their territory (2, 6). Certainly, life outdoors can be harsh. But what would be the alternative? Killing the cats can’t possibly be the more humane option unless they’re terminally ill or injured. Opponents of TNR do have some other suggestions.

A popular one is feeding bans (2, 4). A feeding ban is a law that makes it illegal to feed community cats. Nowhere that supported this solution spelled out why a feeding ban would be better, but I can only assume the idea is to drive cats away from people by withholding food, decrease the population by starving them, or both. Just because it’s illegal doesn’t mean people won’t feed cats, however (5). Even if they did, cats are resourceful. Some would starve, but many more would figure out another way to survive. If the goal is to protect wildlife, a feeding ban certainly wouldn’t help, because cats would only hunt a lot more wildlife and be driven to compete with wild predators.

Another suggestion is to criminalize abandoning cats or otherwise discourage people from abandoning their cats (2, 5). While I wish people didn’t abandon animals, they’re going to no matter what. They always have. People who argue that maintaining managed cat colonies through TNR encourages people to abandon their cats there are really missing the point (5). At any rate, even if no one ever abandoned a cat again, that leaves innumerable cats living on their own already that any action against future abandonment would no address.

There is no such thing as a perfect solution with a problem this complex. However, no one has found a better way than TNR for dealing with community cats humanely and efficiently. Even then, some programs work better than others. Everyone is learning as they go. TNR is still pretty new, but what a difference it has already made.

Ways to Get Involved

TNR can be done as an individual or with a group. Try checking with local animal shelters to see if they know of any groups doing TNR in your area. If you’re going it alone or with a few friends, make sure you’re completely prepared before you start. Alley Cat Allies, the organization that brought TNR to the United States, has excellent online resources, as do Best Friends Animal Society and Neighborhood Cats.

Works Cited

1. Alley Cat Allies. (2011). Why trap-neuter-return feral cats? The case for TNR. https://www.alleycat.org/resources/why-trap-neuter-return-feral-cats-the-case-for-tnr/
2. American Bird Conservancy. (2015). Trap, neuter, release: The wrong solution to a tragic problem. https://abcbirds.org/wp-content/uploads/2015/05/TNR_the-wrong-solution2011.pdf
3. American Society for the Protection of Animals. (n.d.). A closer look at community cats. https://www.aspca.org/animal-homelessness/shelter-intake-and-surrender/closer-look-community-cats
4. Barrows, P. L. (2004). Professional, ethical, and legal dilemmas of trap-neuter-release. American Veterinary Medical Association, 225(9), 1365-1369. https://doi.org/10.2460/javma.2004.225.1365
5. Best Friends Animal Society. (n.d.). Frequently asked questions about TNR. https://resources.bestfriends.org/article/frequently-asked-questions-about-tnr
6. Best Friends Animal Society. (n.d.). TNR for stray cats: Meaning, history, statistics. https://resources.bestfriends.org/article/tnr-stray-cats-meaning-history-statistics
7. Levy, J. K., Gale, D. W., and Gale, L. A. (2000). Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. Journal of the American Veterinary Medical Association, 222(1), 42-46. https://doi.org/10.2460/javma.2003.222.42
8. Levy, J. K., Isaza, N. M., and Scott, K. C. (2014). Effect of high-impact targeted trap-neuter-return and adoption of community cats on cat intake to a shelter. The Veterinary Journal, 201(3), 269-274. https://doi.org/10.1016/j.tvjl.2014.05.001
9. Neighborhood Cats. (n.d.). What is TNR? Managing feral and stray cats. https://www.neighborhoodcats.org/how-to-tnr/getting-started/what-is-tnr
10. Spehard, D. D. and Wolf, P. J. (2017). An examination of an iconic trap-neuter-return program: The Newburyport, Massachusetts case study. Animals, 7(11), 81. https://doi.org/10.3390/ani7110081
11. Spehar, D. D. and Wolf, P. J. (2018). A case study in citizen science: The effectiveness of a trap-neuter-return program in a Chicago neighborhood. Animals, 8(1), 14. https://doi.org/10.3390/ani8010014
12. Swarbrick, H. and Rand, J. (2018). Application of a protocol based on trap-neuter-return (TNR) to manage unowned urban cats on an Australian university campus. Animals, 8(5), 77. https://doi.org/10.3390/ani8050077
13. Tan, K., Rand, J., and Morton, J. (2017). Trap-neuter-return activities in urban stray cat colonies in Australia. Animals, 7(6), 46. https://doi.org/10.3390/ani7060046

Published February 21, 2021