Good News?  Lifetime contraception for female cats.

Guest Opinion by Kip Hansen — 8 June 2023

I have written more than once here at WUWT about the effect that feral cats have on native bird species, particularly low- and ground-nesting species, to say nothing about small reptiles and small mammals. 

There has been on ongoing fight between those who would euthanize all feral cats, the Trap-Neuter-Release advocates and those who consider cats, feral or not, as non-human persons [ personal communication ] and due all the rights and respect due homeless humans.

The media is full of reports of a new (possible) contraception shot for cats – one shot to last a lifetime, with headlines such as :

Science MagazineHello kitty, goodbye kittens? Gene therapy spays cats without surgery

NewScientistOne-off injection may provide lifetime contraception for female cats

New York Times: Gene Therapy May Offer Birth Control for Cats

CNNNonsurgical cat contraception could help curb overpopulation, study says

The ScienceNews piece states: “An injected gene therapy given to female cats prevented them from getting pregnant, researchers report June 6 in Nature Communications. None gave birth to a litter of kittens even after mating with a fertile male. The tactic, if it holds up in further testing, could offer a more efficient way to control a global population of feral cats that numbers in the hundreds of millions.”

“The experimental gene therapy targets anti-Müellerian hormone, also known as Müllerian inhibiting substance, a protein that helps fetal sex organs develop. After injection, a modified virus introduces the gene that makes the hormone into the cats’ cells. The cells then make more anti-Müellerian hormone than normal. High levels of the protein may prevent a cat’s ovaries from releasing eggs by keeping follicles — the structures that house and release eggs — in a dormant state.” [ source ]

Simple injections would certainly speed up the Trap-Neuter-Release programs and injections are far safer, for the cat, than surgery.  Both surgical neutering and this new injection provide permanent contraception in the female feral cats.  And for your beloved tabby at home, the injection would probably be safer (pending more testing), and maybe less cruel, that surgery as well.

The comes the not-so-good news: 

Still, “it’s a really different way to do contraception,” Pépin says. And anti-Müellerian hormone is common among animals, so it may be possible to expand to other invasive species. Pépin and others are even exploring ways to leverage the hormone in humans as a nonpermanent form of contraception (SN: 8/22/17). There’s still a lot to learn, “but I think there’s a great opportunity here.””

Using a method that is apparently permanent in cats and applying it to humans would produce only a nonpermanent form of contraception?  Not permanent sterility?  

We can only wait and see.  Will our sciencey experts limit themselves to sterilizing cats?  Or will they extend their hormone therapy to other invasive species, like humans.

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Authors Comment:

Mid- to long-term contraception, from months to years, might be a good thing for women who do not wish, for whatever their reasons, to be come pregnant and bear children.  I think of high school students and university students, who choose to be sexually active but don’t wish so start families (married or most often not).

Possible permanent contraception, easily delivered as an injection, might tempt too many governmental social programs to opt to effectively sterilize the poor or the otherwise considered unfit, especially in more authoritarian nations. 

Personally, I am a supporter of strong families, permanent when possible, ideally with a father and a mother living and working together to raise their children.    

I am not a supporter of feral cats and tend to the view that they should be systematically eliminated from the environment.  Further, like other animals kept as pets by humans, cats should be restricted to the homes and property of their owners and not allowed to range free.  Pet owners not wishing to be pet breeders should have their pets spayed or neutered.

Opinions vary.

Thanks for reading.

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Ben Vorlich
June 9, 2023 2:28 am

Tend to agree with that.
Although where I am non-native Grey Squirrels are more of a problem than feral cats. Raiding birds nests, above ground level, and invading roof spaces chewing joists and wires. Many people find them cute and feed them which makes matters worse

Reply to  Ben Vorlich
June 9, 2023 3:11 am

They [greys] are tree rats and should be treated accordingly.

Reply to  Ben Vorlich
June 9, 2023 5:23 am

Depending upon where you live, grey squirrels are probably native species and therefore a normal part of the ecosystem, while feral domestic cats are not. Every animal has to eat, and the normal functioning of ecosystems balances out the eaters vs. the food supply.

Reply to  Kip Hansen
June 9, 2023 10:30 am

Natural = cookie cutter housing development
Un-natural = a human on a snow-covered mountaintop

June 9, 2023 2:34 am

How We Domesticated Cats (Twice)

A 9,500-year-old burial in Cyprus represents some of the oldest known evidence of human/cat companionships anywhere in the world. But when did this close relationship between humans and cats start? And how did humans help cats take over the world?

See how Cyprus deals with cats.

Meanwhile at the Louvre, see why Egypt made the cat a God, Bastet, root of the word pussie.

Attaining divinity for services rendered, saving granaries from varmints and pesky birds, means do not mess with cats!

Resist moral panic and the siren call of a lethal silver bullet.
Hey , that applies to climate CO2 too….

Larry The Cat’s Announcement Amid UK Ministers’ Resignation Goes Viral

Reply to  bonbon
June 9, 2023 3:18 am

Larry the Cat at Number 10, the Cabinet Mouser .

Reply to  bonbon
June 9, 2023 3:20 am

It’s a pity the cat isn’t in charge. You know an animal isn’t going to screw you for percentage.

Reply to  bonbon
June 9, 2023 9:09 am

I don’t remember where, but I read recently that cats domesticated themselves.

I’m certain it’s true. Just ask one and he’ll tell you, if he deigns to answer.

Reply to  Kip Hansen
June 9, 2023 10:13 am

Kip, I’ll watch for it

Is it “Polar Bear Evolution”?

June 9, 2023 2:57 am

“There has been on ongoing fight between those who would euthanize all feral cats, the Trap-Neuter-Release advocates and those who consider cats, feral or not, as non-human persons [ personal communication ] and due all the rights and respect due homeless humans.”

It seems to me both sides are bonkers. Where I live there was a massive Victorian insane asylum/mental hospital. When the site was redeveloped for housing a zillion mice were thrown out and they invaded our houses. It was easy, under the terrace of houses the foundations are brick piers and so the vermine can go to any house they choose in the line.

We acquired a kitten in 2013 – one of my sons found it abandoned on Tooting common. So we took it in and she turned out to be a fantastic mouser. Red in tooth and claw.

I make no apologies for that.

Reply to  strativarius
June 9, 2023 5:07 am

People today are being treated as non-humans without sovereign rights.

One might conclude that we are the cats they wish to neuter.

Reply to  Scissor
June 9, 2023 5:23 am

Then Extinction Rebellion’s Last Generation are the Chosen One’s.

Why cannot Cat’s learn tricks like those silly dogs?
Well, the teacher would have to know more than the Cat, impossible.
The Sphinx in Cairo, a homage to a Big Cat (until some darn human pharoah defaced it) calmly gazes east waiting for Leo to rise at Equinox again, like it did 10,000 years ago. Single-minded patience of the lion….

Reply to  Kip Hansen
June 9, 2023 8:11 pm

When the male cats have been trained to use a urinal, then I’ll be impressed.

michael hart
June 9, 2023 3:17 am

I caught one loitering on top of our shed the other morning.

In a panic, when it penned itself in and found the gate too small to scoot round, it had to climb up and over. Unfortunately this included navigating the overgrown rose bush I need to cut back. The rose bush put its many thorns to good use. Best laugh I’ve had in a long time.

June 9, 2023 3:27 am

Administered to humans involuntarily with the next covid or newer pandemic jab.

There are plenty of WEF types who would see this as desirable.

Mad mad world.

Reply to  altipueri
June 9, 2023 5:54 am

Climate nuts would agree, only the chosen few will be allowed to own a car, eat meat, and reproduce.

Rich Davis
June 9, 2023 3:45 am

Using a method that is apparently permanent in cats and applying it to humans would produce only a nonpermanent form of contraception? Not permanent sterility?

Now where have I heard about a gene therapy injected into billions of humans that didn’t actually work for its purported purpose even though it was aggressively pushed by governments that assured us it was safe and effective and needed to be applied on the youngest least at risk of the supposed disease that was not in any case protected against by the shot? Wracking my brain trying to place it.

It might have been called a “vaccine” against a cold virus or something like that. Dang it’s tough getting old when the memory just doesn’t work like it used to!

Reply to  Rich Davis
June 9, 2023 5:08 am

Hello kitty.

Rich Davis
June 9, 2023 4:09 am

cats should be restricted to the homes and property of their owners and not allowed to range free

My owner “Leetal Goral” the tiger cat wishes to make a statement which I must obediently transcribe here.

/start transcript
I find your opinion very offensive. It is our human pets that should be kept locked up in their coops where they can always be available to provide food and open the door on demand. It is bad enough that most days when I wake my pet up at 3:30 am, he usually doesn’t comply with my demands for food and egress. The true outrage is that he and the she-pet sometimes disappear for days at a time leaving only hideous dry food and water for their owner. And now this evil screed about a) cat persons being the actual pets; and b) the mind-boggling concept that we should be confined to our homes while the pets roam free!

I can’t even!

/end transcript

June 9, 2023 4:13 am

And, of course, when I see a discussion of neutering pets, I’m reminded of the Far Side cartoon of the dog complaining that he thought he was going to be tutored…or something to that effect.


Rich Davis
Reply to  Bob Tisdale
June 9, 2023 4:23 am

comment image

Reply to  Rich Davis
June 9, 2023 4:47 am

Thanks, Rich.


June 9, 2023 4:59 am

Which is more cost effective, injections of chemicals or injections of lead?

Reply to  Kip Hansen
June 12, 2023 10:34 am

Was that vitamin D deficiency? I know scurvy is Vitamin C.

Mike McMillan
June 9, 2023 5:16 am


Cats are part of the natural selection process for “songbirds” and mice and other vermin.

June 9, 2023 5:20 am

Weird that there is so much emphasis in this post on the “risks” of spaying female cats, when the operation is considered by vets to be extremely safe.

Additionally, spaying (removal of ovaries and uterus) eliminates the very real risk of uterine and ovarian cancer, a major killer of female cats (and other animals including humans). If there is so much risk from the surgery, then present a comparative risk analysis, showing change in total life risk from spaying vs. not spaying. It seems rather likely than not to produce a reduction in total life risk as a result of spaying.

Plus, what are the risks associated this injection, which went unmentioned in the post? I am by no means an anti-vaxxer, but all vaccines carry at least some risk, and the newer the vaccine such as this one, the less certainty there is regarding its risks.

Richard Page
Reply to  Duane
June 9, 2023 5:44 am

I think what the author meant was that an injection, where there is minimal physical disruption, is safer than any form of invasive surgery, which always has a certain degree of risk.
As the article doesn’t mention risks from the injected therapy, it would be foolish to attempt empty speculation on the completely unknown. If you have any information that you based your comment on, as to the efficacy or inherent dangers of these injections, why haven’t you posted them?

Reply to  Richard Page
June 9, 2023 7:13 am

There is always a non-zero risk from injections which was not even mentioned in the post, while the risk from the spaying surgery is extremely low, as all vets will attest. I have never heard of a spayed cat dying from the surgery, nor never had a vet suggest that it is a risk that is even measurable. The risk from uterine and ovarian cancer is, according to vets, relatively high.

Lee Riffee
Reply to  Duane
June 9, 2023 7:55 am

The thing about surgery for female cats is that the cat cannot be released outdoors until it heals from said surgery. I caught a feral cat that had a litter of kittens under my tool shed and had her fixed. But I had to confine her to my basement bathroom for ten days (she was too wild to let loose in the house and could not be handled without wearing heavy gloves) until she was healed before I could release her outdoors. A shot would make it easier to neuter and release such feral cats.

Lee Riffee
Reply to  Lee Riffee
June 9, 2023 7:56 am

As for the kittens, I kept two as indoor cats and gave the other two away.

Rick C
Reply to  Duane
June 9, 2023 8:31 am

If the injection does not prevent the cat from coming into heat, hard pass here. There is nothing more annoying and pitiful than a cat in heat with no Tom in sight.

Reply to  Kip Hansen
June 9, 2023 10:45 am

Obviously the discussed gene therapy injection needs a lot of testing before it will become available even for cats.

I can’t believe no one responded. You lobbed a perfect lob shot for the super smash.

June 9, 2023 5:40 am

It’s worthwhile perusing the US Fish & Wildlife Service data on bird mortality and its causes in the US.

The single largest source of bird kills in the US is cats, accounting for 2.4 billion of 3.3 billion total bird deaths per year, way more than half. Collisions with buildings are the second highest source accounting for 600 million dead birds per year.

Despite all of the caterwauling and crocodile tears shed here at WUWT over birds colliding with windmills, that source only accounts for 234 thousand (0.0002 billion) bird deaths a year. That would be 0.07% of total bird mortality, which is vastly below the noise level of bird deaths. FFWS’s bird mortality data have an uncertainty range of around plus or minus 44%.

Reply to  Duane
June 9, 2023 7:17 am

For the downvoters – data are data, science is science, and the numbers are the numbers. These aren’t model results. USFWS is the expert on this in the US. If you don’t like the numbers and the reality behind it, then shame on you as a science denier.

Reply to  Duane
June 9, 2023 9:21 am

What you consider to be data, rarely is.
BTW, if you think the data you presented isn’t the result of models, then you are utterly clueless. Do you actually believe researchers ran all over the country counting dead birds?

Rich Davis
Reply to  Kip Hansen
June 9, 2023 3:19 pm

No, no, Kip. Duane must be right. Leetal Goral comes home with a bald eagle, a red tailed hawk, and a California condor almost every millennium.

Reply to  Duane
June 9, 2023 10:15 am

The numbers are really suspect. Aside from cats and buildings, that leaves only 10% of all “bird kills” to be caused by all other factors — raptors, canines, rodents, territorial squabbles — and should be compared to the billions dead from disease, starvation, and old age.

Rich Davis
Reply to  Duane
June 9, 2023 3:27 pm

Don’t be a moron Duane. Combining sparrow deaths by housecat with raptor deaths by windmill and calling both “bird” deaths is either monumentally obtuse or chutzpah on a legendary scale.

Gunga Din
Reply to  Duane
June 9, 2023 8:52 am

So it’s OK for windmills to kill birds?
How many raptors, such as Bald Eagles, do cats and windmills kill?

PS I remember reading a story about a live cam being set up at a Bald Eagle’s nest. Some viewers were horrified when Mom (maybe Dad) brought a cat “home” to feed to the chicks.

Reply to  Kip Hansen
June 9, 2023 10:53 am

I remember sitting on my back porch with barbeque guests when a hawk swooped down, grabbed the little bunny that lived under my porch (our noise on the porch had scared it into the garden during daylight) and dropped it inert into my neighbor’s fenced yard. It made a terrible “donk” sound bouncing off the fence top. The neighbor’s dog then “defended” the inert bunny. I was disappointed because the bunny had done such nice work eating all the dandelion flowers out of my grass.

Reply to  Duane
June 9, 2023 9:20 am

If data is data, then NOAA’s temperature charts, especially the post cooking ones must be true.

Beyond that three points
1) How are these numbers calculated. Do they assign researchers to follow cats around and count the kills? Or are these just estimates.
2) As to the bird shredders, it’s hard to count what you refuse to admit even exists.
3) Like your inane comments regarding car fires, you once again neglect to account for ratios. There are hundreds of millions of buildings all over the country. The number of bird shredders is still small, though growing.

Coach Springer
June 9, 2023 6:05 am

Is this birth control or chemical sterilization? Other than that, I’ll pass on this fantastic opportunity to argue in a binary manner.

June 9, 2023 6:35 am

All night long German Leopard 2 heavy metal cats were spayed on the Steppe.

Richard Page
Reply to  bonbon
June 9, 2023 9:24 am

Well one anyway, and a harvester as well!

Rud Istvan
June 9, 2023 8:09 am

There are several different long acting reversible contraceptives (LARCs) already approved for humans. Depending on which one, they can last for up to several years, and the contraceptive effect is reversed after they are removed. So there is no human need for this new thing that apparently permanently sterilizes cats.

Alan Watt, Climate Denialist Level 7
Reply to  Kip Hansen
June 10, 2023 9:33 am


It’s always required using two hands to find out what time it is — a big one and a little one.

Reply to  Alan Watt, Climate Denialist Level 7
June 12, 2023 10:43 am

I’ve seen watches designed with but a single hour hand. Some with no markings to indicate hours, just a featureless background. Obviously intended for folks who wanted something that looked good, not something useful.

June 9, 2023 10:28 am

Don’t tell Bill Gates if it reservoir soluble. UN’s global population chart? There is so much more danger than feral cats.

Joe Gordon
June 9, 2023 12:34 pm

I like the idea – this shot apparently introduces a gene that produces a hormone that prevents female cats from going into heat. Many people spay their pets simply for the reason that if you’ve ever been around a female cat in heat that isn’t getting any male attention, it’s not fun at all. For them or for us. Their inclination is to get outside and add to the population. That’s why we always have our female cats spayed, even though they’re strictly indoor cats.

So this would be helpful to those of us who love housecats as well as serving as a cheaper and more humane way to deal with feral cats. Animal control could add a radio tag to the shot so that they know which feral cats have already been dosed.

I’ll steer clear of the songbird argument. I know there are many bird lovers here, too. And we’d hate it if one of our cats got out and managed to hurt or kill one. So I get that there are many people who really don’t like cats.

And, if you’ve been so indoctrinated by the schools, perhaps you could even make a case that cat-expelled CO2 has extra triple-super-duper greenhouse properties.

Alan Watt, Climate Denialist Level 7
June 10, 2023 9:22 am

Using a method that is apparently permanent in cats and applying it to humans would produce only a nonpermanent form of contraception?  Not permanent sterility?

We can only wait and see. Will our sciencey experts limit themselves to sterilizing cats? Or will they extend their hormone therapy to other invasive species, like humans.

Yes, but think of the conversational possibilities this opens up next time you encounter an Extinction Rebellion protester: “just sign up for this free clinical trial and you become a lifetime member of the Paul R. Ehrlich responsible non-reproduction society.”

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