From the February issue of Forum
By Debbie Hirst, AmSoc member
The cat and dog overpopulation problem is serious in Sao Paulo. While official statistics do not exist, it is estimated that there are approximately 1.5 million dogs and cats living on the streets of the city. 
It may not be so obvious in some of the nicer neighborhoods of town, but as soon as you get a little closer to the periferia, it becomes impossible to ignore. Abandoned or homeless animals are not the only ones that suffer. Errant animals can cause car accidents, and cats and dogs can carry diseases that are communicable to humans, the most serious of which being rabies.
The World Health Organization (WHO) declared in 1992 that without canine population control one cannot control rabies. Therefore, while it is certainly a humane goal to end canine overpopulation, it is also urgent for public health authorities.
Sao Paulo and Brazil are not the only places where pet overpopulation problems exist. Even in the United States it is estimated that 4 million healthy cats and dogs are euthanized each year in shelters around the country. The problem is multi-faceted, and the solution includes educational programs as well as sterilization projects.
Statistical studies indicate that in order to fully control a population, you need to achieve a 70 percent sterilization rate of the animals within a particular community. Once you reach the 70 percent threshold, the probability that an unsterilized female comes into contact with an unsterilized male is sufficiently small, and the population stops growing.
The challenge is how to achieve that level.
Animal population cannot be controlled by simply picking up the animals and killing them. If it is possible for an animal to survive on the streets (and in countries such as Brazil, where garbage and other sources of animal nutrition are readily available on the streets), as soon as you remove one animal from the location, another one will move in to take its place, and animals will continue having litters until the feeding capacity of the region is met. As long as it’s possible for animals to survive in the streets, there will be animals in the streets. In the United States, the general trend in reduction of street animals occurred simultaneous to the introduction of organized garbage collection programs, so there was no longer a readily accessible source of sustenance for the street animals.
The traditional approach to sterilization has been surgical. For the last several decades a strategy of high-volume, low-cost sterilization programs has been adopted in a number of communities, with varying degrees of success. There is a particular surgical technique that facilitates this type of program (the incision is quite small and often times the only sutures are internal, meaning that the animal does not have to be kept overnight in the clinic or return for any follow-up care). This allows for the surgery to be quicker, and less expensive.
Unfortunately there are not a lot of veterinarians who are interested in becoming adept at the technique required to perform high volume low cost surgeries, and it does in fact require a particular skillset that not all veterinarians have.
The city of Sao Paulo has encouraged clinics to offer sterilization services, specifically by promoting a program where clinics (and now NGOs) can become qualified to offer free surgeries to clients, and in return the city pays the clinics a fixed price for each surgery. The program requires anyone who is interested in taking advantage of the offer to go in person to the Centro de Controle de Zoonoses in Santana to register. For a city as large as Sao Paulo, and with a population as poor, this becomes problematic because many people simply do not have the means to get to Santana in order sign up for the program. It is a good start however.
While high-volume low-cost sterilization surgeries may be relatively new in Sao Paulo (within the last 10 years), there have been similar programs in other countries (most notably the U.S.) for several decades. By and large, the evidence has shown that even with aggressive surgical sterilization programs, it is very difficult to get to a point where you are no longer killing unwanted animals. Most likely, additional solutions will need to be found.
One of these is chemical sterilization, via an injection and not a surgery. Some products already exist and are being used in various countries. In Brazil a product exists for male dogs. The benefit to this type of sterilization is that you don’t need to do it in a clinic, it is much less expensive than a surgery, and you can achieve a very high volume in a short time, therefore facilitating getting to the required 70 percent sterilized level which will achieve effective population control. The product is new, however, and is not being widely used yet.
Two good sources of information on the topic and where you can adopt a cat and dog if you are interested are www.arcabrasil.org.br and www.institutoninarosa.org.br.
Hirst is the owner of spay/neuter clinic Centro de Planejamento de Natalidade Animal, which can be reached at www.cpna.com.br, or 5631 0713. Learn more about injectable sterilants at www.infertile.com.br.