TNR Explained and How One Shelter Does It Right

Understand how TNR (trap, neuter, return) works, why it’s important, and how one large city shelter supersizes efforts to tackle cat overpopulation.

TNR stands for Trap Neuter Return and it’s so important to controlling the community (outdoor) cat population. To those of us in the foster/rescue world, it’s a common thing, but so many people don’t know what it’s all about and why we do it. Let’s look at TNR in detail and I’ll answer all your questions on how it works, why it works, and how one shelter is facing overpopulation head on.

tabby cat in carrier
Adorable Zinfandel, TNR kitty.

Gross Stuff Disclaimer: I’ve included some pics of oddly fascinating and gross surgeries in this post. If that will upset you, please stop at the October 2019 TNR Clinic section.

Fact & Figures

  • Average litter size: 3-5 kittens
  • Female cats are seasonally polyoestrous, going into heat multiple times a year, often (but not always) based on temperature
  • Northern Hemisphere’s Season of love = January – mid-October
  • A 15-year-old female cat could produce up to 180 kittens in her lifetime
  • Cats typically go into heat every 2-3 weeks until they get pregnant

Sources: Vetinfo, DVM360, The Nest

Quick Q&A

Why is there a cat overpopulation issue?

Cats reproduce at a very fast rate, and don’t have a ton of predators, especially in cities where stray cat populations are extremely high. Past population management practices of euthanasia and food bans weren’t effective, but in areas that practice TNR, shelters see less cats coming through their doors.

chart of cat reproduction stats
Simplistic chart from Life With Cats shows how one cat can turn into many.

How exactly does TNR work?

First, a humane trap is loaded up with nice, stinky fish, like tuna or sardines, or even KFC fried chicken. Although this setup is extremely shady (let’s be honest), most cats give in because they’re hungry. Once in the trap, the cat goes to the shelter for:

  • Spay/Neuter
  • Vaccination
  • Flea treatment
  • Ear tip – Makes it easier to quickly ID altered outdoor cats – don’t worry, it doesn’t hurt and they can hear just fine.
black cat ear tip
Tip of ear is removed to identify spayed and neutered outdoor cats at a distance.

Once healed, the cat returns to live ball-less (or ovary-less) and flawless.

Do you have to fix community cats?

Yes. Spaying and neutering makes them calmer and healthier, prevents death during labor, and removes the urge to mate, which also leads to less fights and injuries.

What happens to pregnant cats that come in for TNR?

As long as the cat isn’t in active labor, vets perform a spay abort surgery. I know this can be emotionally jarring, but please remember that the health of the mama cat is paramount. They can die during labor, or have kittens when they are kittens themselves and abandon them in confusion, leaving the kittens to starve to death. The healthiest and best thing is to prevent labor when possible. For more on this topic and common practice, take a look at this article from

But kittens are cute, Liz:-( Do we have to stop the cycle?

Kittens are cute. Dying, sick, and genetically deformed kittens are not. According to, more than 75% of kittens born to feral cats die in the first few weeks, and I’ve seen it firsthand. My current foster kittens, Wonton and Eggroll, were a litter of four, and without human intervention, Eggroll would have been the only survivor:

  • One kitten died after birth.
  • A caretaker pulled Wonton out of the placenta to save him.
  • At just a few weeks old, their brother Jalapeño was humanely euthanized because of a congenital heart defect.

These stories are the norm, not the exception.

Why can’t you adopt them so they don’t have to live outside?

Super friendly cats are adopted, but many community cats aren’t properly socialized. Living indoors is stressful and depressing for them, and with a caretaker, they live just as long as indoor cats. Look how happy my former foster Lemon (Wonton & Eggroll’s mom) is outside:

But I feel bad when it’s cold or hot.

Don’t worry, community cats are very resourceful survivalists. They’ll find shelter when it’s cold, and they have unique ways to cool themselves (like grooming) when it’s hot. If you’re super concerned, you can build a cat shelter in the winter and create a shaded place for them to relax in the summer.

Why can’t you move all the cats out of a city after they’re fixed?

If you remove an animal from a location that contains everything needed to survive (food, water, shelter), another animal will move in. Because you can’t stop this cycle, the best thing to do is stop reproduction and let the cats stay. As a bonus, they’ll keep rodent populations in check.

TNR Clinics: How One Shelter Is Tackling Cat Overpopulation

ACCT Philly, Philadelphia’s only open intake shelter, had over 17,000 animals coming through its doors in 2019, with 10,000 being cats, mostly strays. Regardless of ACCT’s capacity and limited resources, the shelter’s contract with the city means they must take every animal surrendered, which makes managing intake numbers a priority. Any influx of kittens, especially during the summer months, puts a physical and mental strain on ACCT’s staff, volunteers, and fosters.

ACCT Philly has an ongoing TNR program managed by the amazing Alley Cagnazzi. As part of the program, Alley organizes TNR clinics where vets, vet techs and shelter volunteers spay and neuter about 100 community cats (outdoor-only cats) for free. While these clinics are a huge win, volunteer and foster Marta Gambone dreamed of even larger TNR clinics, so she proposed her idea to Alley.

two women in front of cat kennels
Alley and Marta work together to organize bigger and better TNR clinics at ACCT Philly.

Alley reflects, “I was so excited. Marta has tons of connections in the vet world and I knew she’d be a huge asset in making these events successful.”

Marta, who is also a Philly Mag 2020 Happening List Volunteer nominee, was confident in recruiting volunteers, “I knew if we put out a call, the local veterinary professionals would respond.”

And boy, did they.

Gross Stuff Disclaimer: Surgery pics ahead.

October 2019 TNR Clinic

cats in surgery
Row of spay surgeries at ACCT.

Two days before the October TNR clinic, local trapping group Cat Trappers 215 began bringing community cats to ACCT Philly. Once the weekend started, volunteers didn’t know what to expect, but they certainly knew how to deliver, spaying and neutering 267 community cats!

cats in traps
Fixed kitties.

About half of the cats are female, and each can average 12 kittens a year. Just one clinic prevents the creation of 1,200 stray kittens the first year alone, plus many generations of strays.

Wendy, Trooper Vet Hospital
women about to shave cat in surgery
Wendy and Karen from Trooper Vet prep a cat for spay surgery.

The vets, nurses, techs, and volunteers enjoyed it so much, they wanted to do it again. So, Marta organized another TNR clinic in February 2020: A Date with Spay-ghetti, No Balls. This time, Wendy from Trooper Vet prepped by recruiting more coworkers to join. Her stellar recruiting skills also landed a donation of Revolution, a vet-prescribed flea med.

February 2020 TNR Clinic

tabby cats on table
Tabby boys getting prepped for neuters.

While the goal was to perform 200 community cat surgeries, several days of rain sent cats into hiding, so 100 cats were spayed and neutered. This left time for an additional 50 dogs and cats in the shelter to get emergency surgery, including tail amputations and wound repairs. Marta was extremely happy with the clinic, “There are no words to describe the incredible gratitude to selfless volunteers who helped.”

vet and volunteer check cat's mouth
Dr. Dana Yard from Wissahickon Creek and Marta check for a polyp on a cat. The caretaker was worried that the cat couldn’t meow.

Volunteers also recognize the importance of their contribution, as well as building relationships with other volunteers.

“As a high-volume spay and neuter veterinarian, I view my skills as a gift that I can sometimes donate to others who desperately need it . . . It’s personally fulfilling and allows me to make new friends, network, learn new skills and mentor others.

Dr. Nicole Paul, No Nonsense Neutering and ACCT Philly

Nothing makes me happier than to know I made a positive difference in the life of an animal. Working with an amazing group of like-minded people makes the TNR clinic even more special.

Wendy, Trooper Vet Hospital

In addition to fostering an impressive number of cats from ACCT Philly, The Philly Kitty, and City of Elderly Love, Holly Dixon still finds time to volunteer at the TNR clinics, and shares, “Working side-by-side with so many generous caring people makes the experience even more enjoyable.”

three women care for cat post surgery
Olivia, Keila and Holly administer vaccinations and flea meds, take weight, and check ears and teeth.

Gross Stuff Disclaimer: You’re about to see two uteruses removed.

TNR in Action: Meet a Community Cat, Mama DC

Sometimes, it’s hard to wrap your head around how this all works. Let’s take a look at Mama DC. She came to the TNR clinic pregnant but was not in active labor. As I mentioned earlier, in these cases, vets perform a spay abort for a number of reasons: It improves the female cat’s health and also helps control overpopulation (read more here). Her caretaker happily shared a pic of her back in her domain, healthy, happy, and sporting a swanky new ear tip.

Hazel: A Dog’s Life Saved

It wasn’t just about the kitties. One of the non-TNR surgeries saved a dog’s life.

A pyometra (pyo) is an infection in the uterus commonly found in unspayed cats and dogs. Without a spay surgery, the uterus ruptures, spreads infection throughout the body, and kills the animal. Many pyos are discovered during TNR procedures.

Hazel, a sweet pup who was surrendered at ACCT, was suspected of having a pyo close to rupturing. Vets and volunteers got to work to save her life.

During surgery, the uterus was touched and it immediately exploded. Next, vets worked to remove the largest (and stinkiest) pyo they had ever seen and clean out as much infection as possible.

All the volunteers were relieved when adorable Hazel woke up post-op. Thanks to the quick response from vets and volunteers, Hazel is alive and thriving in foster care.

What’s Next & How to Help

You’re invited: Join the next TNR clinic in April!

Marta, the woman whose idea started it all, told me, “We’re always looking for more vets, vet techs, and non-surgical volunteers to join us.” And let’s be honest … how can you resist these two faces?

woman with orange and white cat
Marta and this tubby kitty want you to help at the next TNR clinic.

Want to volunteer?

Want to donate?

Services are free to trappers who bring community (outdoor-only) cats. But the actual cost for anesthesia, shots and flea treatment is $35/cat. To help cover the cost, donate here.

Need help with strays? Want to learn more about TNR or start trapping?

Live in Philly? Email Alley at ACCT Philly,, and she will help or point you in the right direction. Other Philly TNR resources include Catadelphia, Temple Cats, and Cat Trappers 215.

Not in Philly? Contact your local shelter or Google for TNR programs in your area. In Jersey? Contact Angelo Ruffo, The Mad Catter, for an upcoming info session in Voorhees.

Special Thanks

four women around cat in surgical suite
Trooper vet volunteers, Keila, Wendy, Jules and Olivia, take care of a TNR kitty.

Thank you to ACCT Philly for providing the space and always pushing for bigger and better solutions for community cats. Big thank you to Alley and Marta for making this entire event a reality, and to all the volunteers, listed below.

If you’re looking for a vet, maybe one of these hospitals is the right place for your pet:

tuxedo cat post spay surgery
This little lady thanks you for reading.

Related Posts

Why spay and neuter? It’s all in this Top 10 List!

Read about my foster Sprinkle and how a spay saved her life.

By LizsKittyBootCamp

Hi, I'm Liz, and I'm a cat behaviorist who provides advice and insights on cat behavior.