A vasectomy or hysterectomy procedure could prove more effective than spaying and neutering in feral cats, according to a new study conducted by researchers at the Tufts University. The study is published in the August 15 issue of the Journal of the American Veterinary Medical Association.
Even though vasectomized cats lose the ability to reproduce, they successfully retain reproductive hormones which in turn help them protect their territory from sexually intact competitors, ward off new strays, and compete for females. On the other hand, dominant males that are castrated in a TNR program become sexually inactive and are replaced in the breeding hierarchy by the next most dominant male.
Veterinarians from Tufts University's Cummings School of Veterinary Medicine arrived at the conclusion after using a computer-based model. They found trap-vasectomy-hysterectomy-release (TVHR) a better alternative to trap-neuter-release (TNR).
"With TVHR, a male cat's life span, sexual drive and social status aren't altered with a vasectomy, so he'll fend off competing males who try to intrude into his area even though he can't actually produce offspring," said J. Michael Reed, one of the authors and professor of biology in the Tufts' School of Arts and Sciences.
Reed said that if an intact female cat mates with a vasectomised male, it enters into a prolonged state of 45-day 'non-receptive' pseudo-pregnancy period after sexual activity, which in turn results in fewer successful matings in the colony.
Stephen H. Levine, a professor of civil and environmental engineering at Tufts University School of Engineering, developed the computer model to compare the effectiveness of vasectomy (vs. castration) and hysterectomy (vs. ovariohysterectomy). Each computer model included a cat population of over 6,000 days and tracked individual cats on a daily basis. New cats were added to the population as they were born and deceased ones were removed.
The simulation showed that the TVHR method could lessen the population of feral cats by half with an annual capture rate of 35 percent and could completely eliminate the colony within 11 years at the same rate. On the other hand, TNR required capturing about 82 percent of the cats in order to eradicate the colony in 11 years.
