TVHR is more effective than TNR, a study concludes.
This is an interesting study that looks at a modified version of Trap-Neuter-Return (TNR) to make it more effective. The good thing is that the study takes TNR seriously as a way to manage feral cat colonies. The study indirectly validates the concept of TNR, which to sterilise the cats and leave them where they are. A humane process. Note: the study1 was a computer simulation. The objective is to carry it out in real life.
So what is TVHR and how does it differ from TNR?
TNR
TNR is well known but it helps to spell out the process. TNR can be called: Trap-Test-Vaccinate-Alter-Release (TTVAR) – “alter” means to neuter (male) or spay (female). The neutering bit of TNR is:
- male: neutering: testicles removed – castration
- female: spaying: removal of the uterus and ovaries
TVHR
The letters stand for Trap-Vasectomies or Hysterectomies-Release
- male: a vasectomy: the tube that carries the sperm is cut
- female: hysterectomy: this is the same as spaying, removal of ovaries and uterus.
The difference between TNR and TVHR is that the male cat is sterilised by castration for TNR and has “the snip” for TVHR.
How can this slight difference make a bit difference in the management of feral cats?
Firstly, the research indicates the following:
| Process | Percentage of cats undergoing process | Effect after 11 years |
| TVHR | 35% of cats | Population of colony would disappear |
| TNR | 82% of cats | Population of colony would disappear |
Why is this? Apparently there are two reasons:
- Feral cat colonies – a group of cats – are controlled by a dominant male. If this cat undergoes a vasectomy he retains his sexual hormones and sex drive (as opposed to the castrated cat). He, therefore mates with the females but produces no kittens. If he had been castrated instead he would lose his sex drive and another dominant, breeding, male feral cat would take over the dominant position and seek out females, creating kittens.
- Also, an intact (non-spayed) female who has mated with a vasectomised male undergoes a 45-day period of pseudo-pregnancy, which is a further barrier to reproduction.
Well, there it is. This is not a magic formula but the study does promote the humane concept of trapping and sterilising feral cats as opposed to simply killing them.
The one downside of TVHR is that the males behave as if they are breeding cats so their behavior is more intrusive for people living in the location of the colony.
Ref: (1) as reported on the website news.nationalgeographic.com (I don’t have a link to the original study, sorry).
Please see expert analysis of this TVHR study and it’s implications, by Peter Wolf of Vox Felina and Best Friends Animal Society:
Reductio ad absurdum
“Results of a new computer model suggest that sterilization via vasectomy and hysterectomy is more effective than traditional spay/neuter at reducing the population of community cats. But the work raises several questions about the model’s validity—and more troubling ones about its implications for animal welfare.”
– see http://www.voxfelina.com/2013/08/tufts-researchtrap-vasectomy-hysterectomy-release/
“JAVMA Letter: A Trojan Horse”
– All Dollars, No Sense
– http://www.voxfelina.com/2013/12/javma-letter-to-the-editor-feral-cat-management/
Thanks for this. I have heard about this and wrote a page about it myself some time ago:
https://pictures-of-cats.org/feral-cat-control-tvhr-better-than-tnr.html
I might do some more work on it. I have left your links in but they are tagged with rel=”nofollow” because I get lots of spam and I can’t encourage it. I like your site though.