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  • Writer's pictureSusan Houser

What is the Most Effective No Kill Technique?

Most industries pay attention to where they were in the past and where they are now. Changes over time in the parameters that are important to an industry allow people to figure out what has worked and how progress has been made. One example of statistics being used to measure progress over time are the medical industry’s use of changes in the causes of human mortality. If we see that more people are dying of diabetes, we know that spending more money on diabetes research and therapy would be a good use of tax dollars, for example. The animal shelter industry has traditionally paid little attention to statistics. When animal shelter statistics are invoked, it is often with the purpose of promoting a particular agenda rather than in an unbiased search for the truth.

A big part of the reason that the shelter industry has paid little attention to statistics is that we do not have any national mechanism for collection of even the most basic shelter statistics, such as how many shelters there are, what their annual intake is, and how many animals are killed in shelters each year. In spite of the lack of statistics, though, there are a few things we can learn from what we have. Even though the absolute numbers we have are estimates, some of the trend lines are pronounced.

Trends over the last 45 years show that sterilization has reduced the number of animals killed in shelters far more than all the other No Kill techniques combined. Even if we look only at the last 15 years, during which No Kill techniques have come to be in wide use, sterilization has still done more to reduce shelter killing than No Kill. This does not mean that No Kill is unimportant – far from it. But it does suggest ways to think about how to improve the situation in some of our most intractable high-kill cities today – cities like Dallas and Houston.

Check out this graph of estimated shelter intake and shelter killing from 1970 to 2000:

Chart 1

From 1970 to 2000 shelter killing appears to have tracked shelter intake very closely, and during that 30-year period both numbers plummeted. Shelter intake declined from an estimated 26 million animals per year to about 7 million, a reduction of 73%. Shelter killing fell from about 23 million per in 1970 to some 5 million per year in 2000, a 78% decline. Even if those numbers are somewhat off, the trend is pretty unmistakable, and it is borne out by actual numbers from several individual cities and counties.

Since shelter killing is a dependent variable to intake, and killing closely tracked intake from 1970 to 2000, an important question is why intake fell so dramatically. There are only three possible reasons for intake to decline significantly. One would be if enforcement changed so that animal control officers were taking in fewer animals. That does not appear to have been what happened between 1970 and 2000. In fact, if anything, enforcement increased during that time because more and more shelters started taking in cats. The second possible explanation is that people became more responsible pet owners and owner surrenders therefore dropped. This may well have happened to some extent. Several shelter directors and workers who were active in the 1970s and 1980s have told me that they noticed that people were more reluctant to surrender animals for trivial reasons. But owner surrenders were only 30-50% of intake in the period from 1970 to 2000, so that alone could not account for the enormous plunge in intake.

The third and by far the most likely reason for the fall in intake was two mass sterilization campaigns that took place between 1970 and 2000. These campaigns appear to have resulted in fewer strays in the environment and fewer litters born to owned pets. The first of these spay-neuter campaigns began in the early 1970s at a time when there was a lot of publicity about the pet overpopulation crisis. Pet overpopulation was a real crisis in the 1970s. Shelters were killing an estimated 23 million animals per year at a time when there were only about 60 million owned pets and only about 63 million households in the United States. Thus, there was more than 1 homeless animal each year for every 3 owned pets and every three households. There were also lots of strays in the environment that were never picked up by animal control, and lots of litters being born to owned pets, whose owners gave the puppies and kittens away to friends and neighbors.

The pet overpopulation crisis was probably a primary reason why private veterinarians began in the 1970s to recommend to their clients that they spay and neuter their pets. Before the 1970s it was rare for veterinarians to recommend sterilization, both because the surgeries were riskier back then and because veterinarians were not convinced that sterilization was healthy for pets. The second wave of mass spay-neuter progress happened from 1990 to 2000, when organizations began offering large-scale low-cost sterilization programs and pediatric spay-neuter was proven to be a safe technique and became common. It appears likely that sterilization was primarily responsible for the fall in shelter intake of some 73% from 1970 to 2000.

Another thing we can deduce from Chart 1 is that in spite of having far fewer animals to deal with, shelters were not taking any effective steps from 1970 to 2000 to increase their live releases. Live releases were about the same in 2000 as in 1970, at about 2 million per year. The fact that live releases stayed the same indicates that shelters during that 30-year period were not making efforts, or at least not making successful efforts, to get more animals out the door alive. Instead, they were relying entirely on fewer animals coming in the door as the way to reduce shelter killing.

No Kill did not really take off in the United States until around the year 2000. By 2000 there were quite a few communities that were saving a majority or all of their healthy animals and a lot of their treatable animals. There were even several small city and county shelters that were saving 90% or more of their intake by 2000. No Kill increased rapidly in popularity in the period from 2000 to 2015, and by 2015 a substantial proportion of the U.S. population was living in communities that had an 80% or better live release rate. In Chart 2, we see that in the years from 2000 to 2015, shelter intake stabilized and shelter killing continued to decline, but at a slower rate. Thus, from 2000 to 2015, shelter killing is no longer in lockstep with intake. Another factor must have been present that was increasing live releases. It seems very likely that that factor was No Kill.

Does the fact that shelter intake held steady from 2000 to 2015 mean that sterilization programs during those years were no longer important? Not really, as shown by Chart 2:

Chart 2

Chart 2

Chart 2 shows that the number of owned pets has continued to grow dramatically from 2000 to 2015, even as shelter intake remained flat in those years. In 1970, the ratio of owned pets to shelter intake was about 2.6 to 1. It is reasonable to assume that such a ratio would still hold true today in the absence of effective spay-neuter initiatives. With a ratio of 2.6 to 1, shelter intake would have been some 50 million per year by 2000 and some 65 million per year by 2015, instead of the 7 million yearly shelter intake we have actually had from 2000 to 2015.

If spay-neuter efforts from 2000 to 2015 have prevented an increased intake of 15 million animals per year (65 million minus 50 million) and No Kill efforts from 2000 to 2015 have reduced shelter killing by 2 million per year (5 million minus 3 million), then it is clear that spay-neuter has continued to be the most effective technique to reduce shelter killing even after intake leveled off in the year 2000. It’s not even close.

Nevertheless, even though the numerical effect of No Kill programs has been much less than the effect of traditional spay-neuter, No Kill is still an essential part of stopping shelter killing. The two million per year shelter animals that are currently being saved by No Kill shelter reforms is a huge accomplishment, and that number can continue to grow until the great majority of the 7 million animals who come into shelters each year are saved.

No Kill also has an importance that goes beyond the numbers. No Kill can make shelters into welcoming community centers. It can prevent the tragedy of a family having to give up a pet because of finances or behavior problems. It can stop the emotional trauma that workers in high-kill shelters suffer. It can illustrate the fact that animal lives have value. And it can influence pet care and veterinary medicine. That’s quite a lot.

Now we get to the importance of all this for deciding policies today. One obvious lesson is that sterilization programs remain important to keep shelter intake suppressed. Another less obvious takeaway is that there are some communities that unfortunately do not seem to have been reached by the spay-neuter campaigns of the last 45 years. In the south part of Dallas, Texas, for example, it is reported that 85% of owned dogs have not been sterilized, compared to 12% nationwide. In cities with high intake, or high numbers of free-roaming animals in the environment, a comprehensive spay-neuter program may be the fastest way to bring shelter killing down even today. This illustrates the importance of looking at each community individually when deciding on how to reform the shelter. Some communities may need an old-fashioned sterilization campaign before they can ever hope to sustain a No Kill effort.


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