Dr Martinez says the profile of the abandoned dog has changed too. Desperate owners now leave their pets at rescue centres. "A lot of people lost jobs, or their salaries are very low and they can't maintain their dogs," he says. "That is now the number one cause of abandonment."
In the summer of 2010, five squads of anti-rabies canine units arrived. The men pulled out their dog-catching cables and, like the cowboys working on nearby ranches, lassoed the dogs. In one day, says Dr Juan Jose Martinez, director of Centro Antirabico, these urban cowboys captured 130 dogs from the streets of Riberas de Bravo.
Imagine, then, the upheaval that upended this imperfect but functioning system, when a manageable 20,000 street dogs swelled into a teeming population of 200,000 mutts - German shepherds, labradors, and the favoured dog of city dwellers for years - the poodle.
The bond between man and his best friend was corrupted. One man nailed a dog to his fence. A gang of ten children lassoed a cat, hurling it up onto the street cables high above, leaving it to dangle there.
In-depth coverage of Mexico's drug warsOn the surface, this breakdown in the relationship between man and beast could be attributed to the brutal violence that tore at the social fabric in Ciudad Juarez between 2008 and 2011.
Often described in simplistic terms as a "drug war" among "drug cartels", the disaster that erupted in this city resulted in the deaths of an estimated 10,000 people, 100,000 abandoned houses and 2,000 businesses shuttered or destroyed in fires - within four years. But no single occurrence in this border city across from El Paso, Texas, explains the roughly 700 dogs found dead on city streets every month, victims of hunger, car tyres - or execution.
When the number of homicides dropped significantly - from an estimated 2,086 in 2011 to 751 in 2012 - many declared an end to Juarez's designation as the "murder capital of the world" and spoke of a city on the mend.
Economic decline and violence
But to this day, the dogs still roam the streets. Their miserable bodies betray the lasting legacy of violence, their wretched lives warning that the human conditions - which ushered in the crisis and determined their sad fate - persist.
Before long, nearly a quarter of the population - some 250,000 people - had fled. Houses emptied out seemingly overnight; entire blocks lay quiet. Meanwhile, every six months, the dogs produced a new brood, a new gang, and the dog population reached crisis levels.
But it wasn't just the killings that led to this exodus. The US recession and competition from China dried up the demand for many goods, and with it went the factory jobs that had lured families north from Veracruz. With no work and no prospects, houses financed by the state would soon be lost. And with a situation so severe and ripe for political points, the governor of Veracruz launched a programme to rescue families from the collapsing border city. And so it was that New Juarez was left to the dogs.
"People opted to abandon them, either inside the houses or opening the doors and setting them loose," says Carolina Montelongo Ponce, director of the veterinarian hospital at a local university.
For months, rescuers arrived in Riberas and other neighbourhoods to find dogs locked inside homes, behind fences, left to defend meagre property. "They would leave someone in charge of going and giving the dog water and food," says Martinez. Eventually, the caregivers up and left. "We had many cases of dogs found inside houses, dead or really skinny, or one dog would die and the others would eat him. It was horrible."
The entire world of dog maintenance began to collapse, pulled down by the destruction of the people in Ciudad Juarez. Pet adoptions dropped to zero. Sterilisation campaigns ended after mobile clinics came under attack. Dr Martinez remembers the time a group of men arrived at a mobile clinic, and shot their victim in front of other people and pets.
Veterinarians across the city became targets of kidnappings and extortions. After one clinic refused to hand over a payment to a criminal group, says Montelongo Ponce, armed men began firing and drenched the building - still filled with people and animals - with gasoline. Fortunately, for some inexplicable reason, the building did not ignite.
Gangs using dogs for practice
It was in these years of upheaval, animal advocates say, that cases of abuse and mutilation began to appear. Dogs with legs severed clean suggested the work of criminal groups practicing dismemberment. There was no way to know for sure. In this city with a conviction rate of less than five percent, few investigations in human cases produced results, much fewer with animals.
Outrage over both the abuse and the impunity exploited by the criminal and police class alike eventually coalesced around a scrappy dog named Canela ["Cinnamon"]. Like most pets in Juarez, Canela was not confined to a yard. She was prancing around the sidewalk outside her home on a summer day in 2011 when a group of policemen walked by. She began to bark insistently. In front of everyone, an officer drew his .45 handgun and fired it straight into the dog's back.
Canela dragged herself under a pickup truck, without even a whimper, leaving a trail of blood. Local reporters called animal rescue but Canela had suffered significant internal damage; she died within hours.
In a city where public officials routinely characterised victims as criminals, the dog, for sure, was innocent. People protested, holding signs that read: "We speak for those who suffer in silence." An investigation was launched and the policeman who fired the shot was temporarily suspended.
It was as though Juarez had acknowledged that abuse of the weak had to end and that there was no better place to start than with the weakest among them.
Around this time, Barbara Quintana, a college student, began rescuing dogs in her neighbourhood. She says she shooed off some youths who had stuffed a puppy in a sack and used him like a ball. The big labrador mix she found, apparently mutilated in a clandestine dogfight, was nursed back to health and named Rocky.
With a death toll that began declining last year, officials now deliver speeches about Juarez' recovery. Businesspeople see a bright future for Mexico now that the cost of labour there is less than in China, according to a report by Bank of America released in April.