New Study Indicates Vasectomies Might Reduce Feral Cat Populations Most Effectively

We have discussed tubal ligations and vasectomies for dogs and cats on this blog before with a focus on the potential benefits for puppies in shelters.  National Geographic published an article yesterday on a recent study showing the potential benefits of using vasectomies to control feral cat populations.

If you are unfamiliar with tubal ligations and vasectomies for pets, here is an excellent primer.  Basically they are surgical procedures to render pets incapable of reproduction and are far less invasive than traditional spay-neuter.  The procedures allow pets to keep their gonads, and their hormones, and therefore do not affect breeding behavior.  As such, Dr. Khuly notes that tubal ligations and vasectomies for cats are not likely to offer much benefit for owners:

They’re just not behaviorally amenable to in-home living when their ovaries and testicles hold such aggressive sway over their behavior.

But for feral cats, the implications are different:

Using a computer model, the researchers found that colonies of feral cats that were trapped, given vasectomies or hysterectomies, and released (TVHR) shrank faster than colonies that were trapped, neutered, and released (TNR), a method of feral cat control promoted by many cat advocates.

Feral cats live in groups that are controlled by a dominant male. A vasectomy cuts the tube that carries sperm without removing a cat’s testicles, so a vasectomized cat retains its sexual hormones. Thus, it can also keep its dominant position in the colony, so it’s able to mate with females without producing kittens.

Neutered feral tomcats who are returned to their colonies lose their position and another intact male takes over.  Intact females are also impacted because, after mating with a vasectomized male, the female comes out of heat for 45 days which reduces the amount of time she has to become pregnant.

The study’s authors caution that the theory needs to be tested in live cat colonies to see if the computer model’s projections pan out.  And there are some potentially negative ramifications as far as behavior goes – specifically tomcat spraying and fighting – which has been a selling point of traditional TNR.

My thinking is that vasectomies could be another tool in the toolbox in managing feral cat populations.  TVHR might work better in rural colonies where the tomcats’ behavior is unlikely to cause complaints from residents than in urban colonies.  And that’s if the computer model’s success translates to real life results.

30 thoughts on “New Study Indicates Vasectomies Might Reduce Feral Cat Populations Most Effectively

  1. I would also like to know what the failure rate is. I just looked up an article and it says in humans the failure rate can be as high as 1 in 100. A failed vasectomy would make it harder to figure out who is still fertile and producing those kittens since everyone is eartipped.

    1. It is currently very hard to find a vet that offers vasectomies and tubal ligations. That situation could change anytime since the procedures can apparently be learned in an afternoon. My thinking is that unless the market demands the service, vets will continue to ignore it.

      1. Having dealt with both an intact male (got him neutered within a month of him showing up) and an intact female (let a feral cat out in my house because I needed the trap to catch her kittens and couldn’t catch her again for a year) in my house there is no way I would be willing to put up with those behaviors again. I can’t see many people willing to put up with them so I doubt there will be a market for them.

  2. No one would do it. Peter’s right – keeping sexual behaviors may be more effective at reducing populations, but it will lead to an increase in disease and will be a problem for human/cat relations.

    It’s inhumane and doesn’t address the needs of the community as a whole. Pass.

    1. There are some who believe – and I’ll take a wild guess and speculate that probably no YB readers fall into this category – that neutering cats and dogs is inhumane in the sense that it takes away their raison d’etre and alters their behavior so dramatically for human convenience. Juliette de Bairacli Levy comes to mind as one who put forth this view.

      1. I can see early neutering being a problem with growth and whatnot. But the whole “life is all about reproduction” thing can go fly a kite.

  3. I think this is an interesting discussion point and certainly not something to brush off because it’s different than what we’ve traditionally done. I’ve read a lot of articles recently about early spay/neuter and how it can potentially affect the health of dogs and cats as they mature because of the interruption in hormones before they are fully developed. Hormones play a huge part in growth and health, not just sexuality, and it’s certainly worth investigating other alternatives for the health of the animal. Thank you for posting.

  4. This was initially posted in the LA Times, and Vox Felina is all over it. I understand their concern that it wouldn’t curb undesirable behaviors or lower disease rates like a fully neutered colony would accomplish; however, having said that, it is an interesting alternative. It is perhaps not acceptable in a very urban environment, but in a rural environment it may be more effective at population reduction than typical TNR. Remember we aren’t talking about pet cats–we are talking about permanent outdoor feral cats.

    What would be even better is an injection that temporarily or permanently sterilizes cats, with or without behavior modification. That way it could be administered on site, reducing expense, time, and stress on the cats. They already do it for deer, they just have to figure it out for cats.

    1. While chemical sterilization would seemingly be a great innovation for feral cats, there are some pet owners who fear it. One fear I’ve heard expressed is that nutters would get their hands on it (a group like PETA would undoubtedly have access) and secretly use it against owned pets at events such as cat shows, dog shows, etc.

      On Wed, Aug 21, 2013 at 12:30 PM, YesBiscuit!

      1. And pet owners might not want it if it doesn’t curb undesirable behaviors. Both the intact male and female sprayed in my house. I wanted them neutered because I really didn’t want more cats to be born, but I also wanted that spraying to stop. If I get offered an option to neuter that won’t stop the spraying I won’t take it. It also make the female much much nicer – although she still hated me until the day she died.

      2. Many years ago I lived with a family who had 2 spayed female cats. One was a chronic sprayer. IDK how commonly female cats spray but it would be interesting to find out if more female sprayers are intact or spayed.

        On Wed, Aug 21, 2013 at 12:38 PM, YesBiscuit!

      3. I let Kiana loose in the house because I needed the trap, but I didn’t realize that I wouldn’t be able to trap her easily again! Since at that point there were no intact males in the house I figured no big deal and I would spay her when I could catch her. It worked okay for a while but at about the year mark she got frustrated at going into heat so often with no satisfaction and started spraying. And that was when I called friends with heavy gloves and we caught her. After she came home the spraying stopped. She is the only female I have seen who sprayed and I have had about 8 females now.

      4. I’ve had two females who sprayed. Both of them did so when stressed. Only one was kind enough to always do so on the side of the trash bin, where it was easy to clean.

      5. Not sure of the numbers but my vet told me that more neutered females sprayed, I had gone to him with my endlessly spraying female to get some help. She eventually aged out of it but it was years.
        I think the vasectomy/hysterectomy idea is well worth exploring.

      6. I believe spraying is a fairly normal behaviour of intact females. The stray female that came in to have her kittens did it. She ruined a bench/coat tree in our front hall & would also get up on bathroom counter. She continued to have inappropriate urinary habits if she was stressed (if other cats on opposite side of door or window). She likely need to go to a home without other cats. She’s on low carb canned food with no evidence of bladder problems either.

        Info on cat sites implies it’s not unusual for intact females to spray.

        Since spay/neuter helps prevent fighting, it also reduces disease transmission. The article on the TVHR study didn’t mention that. I believe s/n cats are also less stressed, rest more, groom more, and require fewer calories so are able to withstand winters better. These welfare concerns don’t seem important to supporters of TVHR.

      7. Just to clarify Chris, I don’t know of any “supporters of TVHR”. I don’t think it’s fair to characterize any commenters here that way, nor do I think it’s fair to characterize the scientists responsible for the study that way – if either was your intention. I haven’t personally yet read ANYONE who could be characterized as a “supporter of TVHR”. I myself am open to learning more and keeping it as a potential tool in the shed but it’s merely a theoretical discussion at this point since vets don’t offer the service and the model remains untested in real life.

  5. It looks to me like the abstract linked is suggesting that TVHR would likely result in lower survival rates in kittens & juveniles, and this is part of their model:

    When the effect of fraction of adult cats neutered on kitten and young juvenile survival rate was included in the analysis, TNR performed progressively worse and could be counterproductive, such that population size increased, compared with no intervention at all.

    At least, that’s how I interpret it. Overall, too, the model appears to rely in part on lower survival rates, although that isn’t spelled out in the abstract – but I can’t think of any other good reason for the rapid decline of the modeled colony.

    Not what I’d consider humane.

    1. I took it the population decline was based on the fact that vasectomized males were mating with females, putting them out of heat and not getting them pregnant. Truthfully my eyes gloss over when reading a lot of this Smart People Talk so I am not the most reliable source for interpretation. One aspect of TNR that they didn’t seem to address is that in maintained colonies, kittens are sometimes captured, tamed and placed as pets (neutered obviously). IDK if there is sufficient data on that aspect to allow them to factor it in but it’s one of the ways that maintained colonies get to zero population over time.

      On Wed, Aug 21, 2013 at 12:50 PM, YesBiscuit!

      1. Yes, that’s mentioned in the abstract, but … thing is, that would prevent births, I can’t see where it would accelerate attrition.

        I didn’t see removal of kittens and strays from colonies mentioned either. I’m beginning to think it was a closed-system computer model.

  6. Not a fan, either. I think the problems clearly outweigh the benefits. If Eucritta is correct, it’s not even humane. Finally, as far as chemical sterilization, I’d be really concerned that the “wrong” people would get ahold of it and the cats would pay with their lives. As it is there are people who are publicly telling others about ways to kill off feral cats (ie, tylenol, shooting, etc) so we don’t need to put any more weapons in their hands.

    What I do think we need is more education regarding TNR and having more community cats actually involved in a managed (hence, non-intact) colony.

  7. Un-neutered but sterilized male cats will still display typical male behavior, e.g. aggressive behavior to other cats = fighting. Thus abscesses, spread of FELV though bite wounds. It does stop breeding but I don’t see a vasectomy as having overall value for the health of a feral cat colony.

    1. Exactly. Sure, it reduces the population faster, but so does fire, you know? Not a good solution.

    2. I think “health of a feral cat colony” is what is important here. Agree that the aggressive behaviors and resulting diseases and injuries are important considerations.

  8. I think this would be unkind to the poor tomcat, who would still be fighting, spraying, roaming, getting FIV. Does ‘the good of the many outweigh the good of the one?”

    1. Right. All behaviors that would chafe in areas where humans lived as well. Who wins in this scenario? The kittens that aren’t born? Or the kittens that get killed by Toms who are still feeling the hormone-fueled need to compete?

      I don’t see how this model is “better” in any way, shape, or form in the real world. Better numbers does not equal better solution.

      1. We have so many TNR colonies close to apartment complexes and even a day care down here that I think the continued spraying would be a bad idea.

  9. Since welfare of cats is also a concern, I doubt any of the large groups are going to give grants for this. I don’t think I could support it if it’s less humane than s/n.

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