Trap-Alter-Release Programs

The National Pet Alliance (NPA) initially executed a survey, partially funded by the CFA Legislative Matching Fund, to determine the numbers of unowned cats in Santa Clara County, CA. The survey results, which were published in the Almanac (January ’94, p. 71), clearly indicate that reproduction intervention with free-roaming/unowned cats would have the greatest impact on euthanasia of cats in that county’s shelters. Karen Johnson and other NPA members have provided further analysis and information to support this need. The following report was presented to the Santa Clara County Animal Advisory Commission as an alternative to a proposal by the Department of Animal Control to establish cat rabies licensing as a method to fund feral cat trapping. The Commission is reviewing the report and will make recommendations to the County Bureau of Supervisors. This information will be useful for those other communities who want to encourage positive programs focusing on reducing reproduction of unowned cats instead of legislative measures which are directed toward responsible cat owners and breeders.

The most commonly preferred method put forth by animal control organizations for control of cats has traditionally been to capture and euthanize feral/unowned cats. Others, who refer to this means of control as the “trap and kill” method, consider it inhumane and objectionable on several fronts. A major factor is that it has been shown that as soon as a cat is removed, a new one will move in to take over the food source.(1) Additionally, unless the cat is making an unusual pest out of itself, why should a wild animal be euthanized simply for not having a human address?

After a six-year study and daily observation of a feral cat colony, it has been documented that stray female cats start cycling when they are 4 – 6.9 months old,(2) or as soon as the days are long enough. January and February are the start of the kitten season, with the litters born in March and April. These cats have an average of 2.1 litters per year of 4.25 kittens.(3) Forty-two percent of the kittens will die by the age of two months of natural causes.(4) Many more will end up at the shelter. Those who escape early death and the shelter go on to be prolific bearers of kittens over their short life span of approximately three years.(5)

Taking the mortality into account, along with birth and death rates, the average stray female will have 5.25 litters in her lifetime, encompassing 22.3 kittens. At age two months there should be 12.9 survivors, roughly six females and seven males (at maturity, roughly 2/3 of the stray cat population is male,(6) due to the high mortality of females during first pregnancy and birth), which will decrease to four females over time. These six females will go on to have their 22 surviving kittens each.

Realistically, over 12 years one unspayed female with all her unspayed female offspring can reasonably be expected to be responsible for over 3200 kittens if there is no human intervention.

Some continue to advocate the trap and kill eradication approach. However, if eradication programs really worked, we wouldn’t be faced with so many stray cats and their offspring at the shelters. Cats are territorial. They don’t allow other cats into their territory to steal their food. Altered cats will stand their ground and guard their food source, will not have kittens, and will die in a few years. Remove the cat(s) from the habitat without changing the habitat and another cat will move in.

In 1994 the Humane Society of Santa Clara Valley found 37% of their cats euthanized over an 11-month period either were wild, or were their unweaned offspring. Once the offspring of these feral cats are over about six months of age, it is nearly impossible to socialize them to the degree necessary for them to be placed as house pets. An unsocialized cat is an unadoptable cat. The cities and counties pay for the handling of these stray cats and their offspring. Reducing the number of kittens born to these cats would substantially reduce the number of cat euthanasias at the shelter, thereby reducing the costs borne by the taxpayers to handle and kill stray cats which cannot be socialized.

Unowned/wild cats are routinely euthanized at shelters. Even though the kittens can often be socialized for placement, it does take a minimum of two to three weeks of intensive work. Shelters simply don’t have the time, personnel, or cage space to socialize the kittens. Many do not have foster care available for this work. The alternative, for the most part, is euthanasia.


In 1989 Stanford University officials announced a plan to trap and kill approximately 500 stray cats living on campus. At that time Stanford Cat Network (SCN) was formed and was able to present an alternative solution in which they would organize, trap, alter, release, and manage the cats to stop the progression of reproduction on campus. Because of their hard work, Stanford cats now have zero population growth as a result of diligent and ongoing trapping and spay/neuter efforts, and the population is declining through natural attrition. Over 60 kittens were caught, socialized and adopted out during the first season. By 1994 only four kittens were found on campus. The campus population is now estimated at approximately 300 cats. Stanford’s current cat population is healthy and well cared for, and its maintenance involves students, staff, and faculty.

SCN has accomplished all of this without financial support from the University. SCN’s successful five-year program with a very large cat population demonstrates that feral cat colonies can be managed and kept under control, and that a workable, viable alternative to a rush for extermination does exist.

In San Diego County the non-profit Feral Cat Coalition has trapped, altered, and released in excess of 3,100 cats over the past two years. In addition to these cats, which were over five months of age at the time of altering, an unknown number of kittens were also trapped, socialized and adopted into new homes.

Prior to this project, San Diego County Animal Management Information System reported an increase of roughly 10% per year in the number of cats handled by San Diego Animal Control shelters from 1988 to 1992. The increase peaked at 13% from Fiscal Year (FY)91 to FY92, with a total of 19,077 cats handled. After just two years, with no other explanation for the drop, only 12,446 cats were handled – a drop of 35%. Instead of another 10% annual increase, euthanasias plunged 40% from ’91-92 to ’93-94.

San Diego Animal Control Cat Statistics 1988-1994

             Total   Claimed   Adopt.   Euth.   Res.   Oth.*
 '88-89   13929     202        2130     10976      7     614
 '89-90   15394     230        2224     12349      -     591
 '90-91   16849     238        2426     13561      7     617
 '91-92   19077     248        2577     15525      6     721
 '92-93   14143     180        2297     11121      -     545
 '93-94   12446     223        2386      9269      -     568

 *Other includes: return to wild, transfer to correct
  jurisdiction, wildlife rehab, stolen, escaped, DOA, died
  in kennel, died in truck, died at contract vet, misc.

Of the 3,153 cats trapped by the Feral Cat Coalition which were altered, 54% were female, 46% were male. Of the 1639 females spayed, the following characteristics were noted:

 Normal       453 28%
 In Heat      691 42%
 Pregnant     218 13%
 Lactating    216 13%
 Post Queening 61 4%

 Total:      1639 100%

Only 3%, 86 cats total, were found to have been already altered. Seventeen cats were refused surgery for being under five months of age, or too ill. Eighteen cats died during surgery. 679 cats (22%) needed additional medical treatment – generally amoxicillin for infections, or ivomectin for mites or worming. Additionally, cleaning and suturing of wounds and abscesses was very common.

Seventy-two percent of these stray female cats were either in heat, pregnant, or had recently had kittens. This is at least a 3-1/2 times higher incidence of pregnancy than found among owned cats. Three studies have shown between 16-20% of owned cats have a litter prior to altering. A 1991 Massachusetts SPCA study found 20% of owned cats had a litter(7); a Las Vegas Study reported 16% of owned cats reproduced(8); and in the 1993 survey of Santa Clara County residents, 16% also verified that their cats had a litter prior to altering.(9)

Clearly, the project to trap, alter, and release cats in San Diego County has had a dramatic effect on the number of cats handled and euthanized at their shelters, which even historical or nationwide downward trends cannot explain. Santa Clara County Animal Control has estimated that the cost to handle a stray cat for the three required days in the shelter, plus euthanasia and disposal is $70 per cat. There are still only three alternatives to handling the population of stray cats: 1) alter/release/management 2) exterminate/ euthanize 3) ignore.

Let us now compare costs:

  Test/Vaccinate/Alter = $52 on a low cost program
  3 Day required stay at shelter = $70
  Handle 3200 offspring = $224,000

Forty-one percent of the known cat population in Santa Clara County is unowned.(10) This equates to 168,463 cats which will, for the most part, be unaltered. Do we allow them to continue to breed, adding ever more cost to animal control budgets and taxpayer burden, or do we take the initiative to trap, alter, and release them, reducing the number of fertile females to manageable levels?

The months prior to the start of kitten season are the time to start trapping the cats. Every female trapped at that time will reduce the number of kittens which need to be handled by animal control during the summer by at least two. Do we spend $52 now on the spay, or $140 to handle the two kittens estimated to survive in the spring? There are volunteers within a community who care about cats. Animal agencies should aggressively take the lead in encouraging and enabling citizens to help out on this problem. Organization must be established within the community. This enables volunteers to know what to do. Provide the means for the medical treatment, and citizens will provide the services to trap the cats and take them to the veterinarians. But, for the best possible outcome, provide both for those areas with large colonies. Funding for a program of this type can take many forms:

  1. Looking at the figures from San Diego, one can readily see that for a cost of $163,956 (3153 cats x $52 per cat) they have reduced the expenses at their shelter by approximately $455,000 (6500 cats) over a two-year time span. This successful track record shows that in actuality no additional funds need be raised – the program will pay for itself through lower shelter costs. The initial funding for altering could be taken from the shelter budget. (San Diego, however, did not pay for the veterinary services. All services were donated by veterinarians and others. Medical supplies were purchased through contributions to Feral Cat Coalition.)
  2. For those who prefer not to gamble with the shelter budget, an alternative is to request the Board of Supervisors to allocate seed money for a trap/alter/release program, after showing them the future savings to the animal control budget. The City of San Jose found surplus funds in the Animal Licensing budget. Perhaps the County may also find such a surplus.
  3. Alternatively, if a restricted pet product surcharge was proposed in this county, for use only for trap/alter/release program seed money, with the surcharge ending as soon as the program was proving that the shelter costs for stray cats and kittens were decreasing, probably few in the pet community would have an objection. The decreased shelter costs would then more than fund the ongoing trap/alter/release efforts.

There may be those who prefer to continue the eradication method. The concerns put forth are usually centered around noise (cats fighting over territory or mating), smell (of spray), vector infestation, disease transmission or possible injury. The assumption of a quick and clean solution makes this avenue of population control especially attractive. Yet eradication programs are ineffective.(11) While attractive from a theoretical and short-term perspective, eradication has proven to be an elusive goal.(12) Following trap/alter/release programs, mating behavior and noise is eliminated. The male urine spray smell is eliminated. Disease transmission to humans is a negligible factor due to the few diseases which cats can pass to humans. Rabies is one. There were only two cat rabies cases found in 1993 in the entire state of California, out of a current population of some (13) million owned and stray cats. The risk is minimal. Vector problems should increase with removal of stray cats, until such time as an increase in other rodent predators takes the place of the missing cats. Most of us would probably prefer to have a small, healthy feral cat population, rather than a larger Norway rat and seagull population in habitats where those are the only options.(13)


We strongly recommend immediate issuance of vouchers for all unincorporated county residents to take their stray and “loosely owned” neighborhood cats in for free altering. The sooner the program begins, the sooner the reduction in shelter costs will occur. For the fastest method of notifying residents of the programs, perhaps a utility insert, or special mailing to residents could jump start the program fast enough to show reductions in shelter expense within three to four months. Two sample flyers appear below. One is for San Francisco SPCA’s program, the other is for San Jose’s.

We have estimated that due to death of owned cats, in excess of 17,000 kittens are needed annually in Santa Clara County just for replacement. These kittens will need to be altered. It would be ideal to develop the trap/alter/release program in such a way that the 17,000 owners of kittens which need altering, and who could otherwise afford to alter their cat, do not use the voucher funds to the detriment of the stray cat altering program. Eighty-six percent of owned cats in Santa Clara County are altered.(14) From San Diego we know 97% of stray cats are not altered. There is no doubt which cat population is causing the huge numbers of cat euthanasias at the shelter. It’s time to get to work and start altering the stray cats now.

  1. Zaunbrecher, K., & R. Smith, “Neutering of Feral Cats as an Alternative to Eradication Programs,” Journal of American Veterinary Medical Association, 203, No 3, 8/1/93, 449-452.
  2. Jochle, W., & M. Jochle, “Reproduction in a feral cat population and its control with a prolactin inhibitor,” 2nd International Symposium on Canine and Feline Reproduction, Belgium.
  3. Pedersen, N., Feline Husbandry (American Veterinary Publications, 1991), pp. 3-12. (See note below)
  4. Berkeley E.P., Maverick Cats (New England Press, 1982).
  5. Ibid.
  6. Ibid.
  7. Handy, F.L., “Measuring your community’s pet population, owner attitudes,” Shelter Sense, 16, No 5, May 1993:3-12
  8. Mosier, J.E., L.W. Williams & R. Nassar, “Study of feline and canine populations in the Greater Las Vegas Area” AmJ Vet Res., 45, No 2, 1984, 282-7.
  9. Johnson, K., L. Lewellen & J. Lewellen, “National Pet Alliance’s Survey Report on Santa Clara County’s Pet Population,” Cat Fanciers’ Almanac, Jan. 1994, p. 71.
  10. Ibid.
  11. Zaunbrecher, K., op. cit.
  12. Zaunbrecher, K., L. Holton & P. Manzoor, “Managing and Controlling Feral Cat Populations,” Veterinary Forum, March 1993.
  13. Clifton, Merritt, Ed. “Animal People on AOL,” Pet Care – Animals and Society Board, 12/1/94
  14. Johnson, K., op. cit.

The National Pet Alliance, a California non-profit mutual benefit corporation, was formed five years ago to promote the well-being and preservation of domesticated cats and dogs. The original intent was to set a standard of excellence among cat and dog fanciers with regard to the care and housing of animals, and to establish a mentoring program for those who were new to the world of animal breeding and exhibition. The organization has been diverted from its original goals by the type of anti-animal legislation which began in 1990 with the introduction of the San Mateo ordinance to ban all breeding of cats and dogs. Instead of being able to teach and promote the best of the animal fancier world, the directors and supporters of the National Pet Alliance have become defenders for the existence and continuance of the pedigree cat and dog fancies as a whole.

The article published here is an example of the research we are continuously providing to the cat and dog fancy in an effort to get the true facts behind euthanasia at the shelters. Research we have done over the past few years has helped many communities to argue that pedigreed cats and purebred dogs are not the primary source of shelter euthanasias.

We have many more exciting research projects in the works. However, to make the phone calls, mail the letters, copy the reports, etc. costs money. Every penny received by NPA has gone directly to the costs of keeping the fancy informed, copying, phones, supplies, etc. No member of the NPA has received any reimbursement for the hours of time spent helping you.

Please help us continue to bring you quality research by making a donation today to keep our office solvent. Help us help you. If you wish to make a donation you may send it to National Pet Alliance, PO Box 53385, San Jose, CA 95153, 408-363-0700. THE SF/SPCA offers: free spay/neuter surgery for San Francisco cats in May, June and July In an unprecedented offer, The San Francisco SPCA will alter all San Francisco cats – owned or unowned – absolutely free in May, June and July. To take advantage of the SF/SPCA’s free alteration, cats must be vaccinated and pet owners, caretakers and cats must live in San Francisco. Cats have short-term pregnancies and large litters. Two cats can produce thousands of kittens in just a few short years. Spay/neuter surgery not only curtails reproduction – it makes for a healthier, better behaved pet as well. Neutering reduces aggression toward other cats and decreases the liklihood of fight related injuries. It also helps prevent tomcats from spraying and roaming in search of a mate. Spaying prevents problems associated with pregnancies and eliminates the frantic pacing, crying and roaming of a cat in heat. For more information or to make an appointment, call (415) 554-3086. The San Francisco SPCA 2500 16th Street San Francisco, Califorinia 94103 554-3000.

NOTE: Feline Husbandry is out of print, but used copies are sometimes available through

PDF files of the chapters in this book by Dr. Pedersen are available for free download on the UC Davis Center for Companion Animal Health web site.