ISTANBUL — Pinar Satioglu, 48, a dentist from the Anatolian part of Istanbul, leaves her clinic duties behind every Friday, as she has done for the past 20 years. Instead of treating dental patients, she spends her day at the Kadikoy Municipality’s Center for Street Dog Rehabilitation, feeding, walking and giving care to about 400 rescued dogs.

In Istanbul alone, a megacity of 15 million people, there are thought to be 130,000 dogs and 125,000 cats roaming free. These animals in all of Turkey’s urban centers now get services from local governments: shelter, regular feeding, sterilization and medical checks by trained veterinarians.

It wasn’t always that way. “Municipalities around Turkey poisoned hundreds of dogs in the late ’90s and early 2000s,” Dr. Satioglu said. “This poison is not only the most painful and inhumane way to kill the dogs, but it was also a public health hazard. It enters the soil, the water and gets in contact with children playing in the streets.” On one summer day in 1998, she saw a pile of bodies — perhaps 60 dogs. They had been poisoned with citrinin. She and fellow animal lovers staged a demonstration that day to protest the mass killings of street dogs.

Street animals, particularly dogs, are often a part of the urban landscape in developing countries. This endangers human health. They bite, and their feces on the street may be a serious hazard, containing microorganisms that not only are pathogenic to humans, but in some cases are also resistant to antibiotics. The most serious consequence is rabies. According to the World Health Organization, more than three billion people, about half of the world’s population, live in countries and territories where dog rabies exists. The virus takes 55,000 lives each year in Africa and Asia alone.