The number of surgical sterilizations that should be conducted in ethical control population campaigns to obtain satisfactory results (modification of dog or cat population growth rates) is inferred from the estimated number of urban stray dogs. The literature on the issue is sparse and its scientific reliability, poor. Therefore, before starting with the actions of ethical dog population control in the city of Buenos Aires, and with the aim of estimating the number of dogs without responsible holder, a sampling in the 15 communes of the city was performed.

From the results of a pre-sampling carried out between 9 a.m. and 12 a.m., a protocol of double grid sampling at 7 a.m. and 7 p.m. on different days was established. Samples were taken in clusters, covering blocks from all districts of the Autonomous City of Buenos Aires, following a systematic Greek guard pattern. A total of 1621 blocks - that guaranteed an absolute error ≤5% for an estimated prevalence of 1 dog/block and with a 95% confidence - were sampled. According to sightings made (208), 91.73±33.12 total canines without responsible owner could be found in 1000 blocks. Projecting the results obtained throughout the city, an amount of 2591±130 canines could be present in that area.