PHOENIX -- A pack of 26 stray Chihuahuas rode 2,400 miles in the back of an SUV in late March, a cross-country trip from a Phoenix animal shelter to another just outside Philadelphia, where all but one were adopted in days.
That same week, a retired orthopedic surgeon, Peter Rork, loaded 30 other Chihuahuas into his retrofitted Cessna 206 and flew them from Phoenix to Boise, Idaho, where small dogs are a hot commodity. Next month, he will fly about 36 Chihuahuas from Scottsdale, Ariz., to the same destination.
"Supply and demand, that's what it boils down to," said Judy Zimet, a Phoenix real estate lawyer who serves as executive director of Dog Is My Copilot, Dr. Rork's rescue group. "In Phoenix, Chihuahuas are a dime a dozen; in Idaho and Montana, there are so few of them you have to get on a waiting list to adopt them."
Arizona's most popular exports have long included the "four C's," as they are known in this state: copper, cattle, citrus and cotton. And lately, Chihuahuas could almost join that list.
The breed, which traces its roots to Mexico, is so popular in Arizona that some neighborhoods of Phoenix have become overrun with them. Stray Chihuahuas roam the streets, overcrowd animal shelters and have exhausted the charitable network of foster families who take them in but can no longer take one more.
To avoid euthanizing the dogs, animal welfare workers have started shipping them to faraway states and even repatriating them abroad: Arizona Chihuahuas have emigrated to Canada and Russia, said Joe Pyritz, a spokesman for Pinal County, whose animal shelter cares for Chihuahuas carried by migrants caught crossing the border illegally.
Only pit bulls outnumber Chihuahuas in the Maricopa County shelter, and the number of Chihuahuas has risen steadily since 2011 while the number of pit bulls has declined. At the Arizona Humane Society, the state's largest animal welfare agency, Chihuahuas overtook pit bulls this year in number.
Since January, the Arizona Chihuahua Rescue, a volunteer organization that takes in Chihuahuas nobody wants, has posted a warning message on its home page: "We are unable to accept any new dogs."
The reason Chihuahuas and their many mixes are among the dogs most often found in animal shelters, animal-care workers say, lies somewhere in the intersection of geography, pop culture and immigrant tastes. Breeders play a role, too: Some do not realize that female Chihuahuas are so small that they often need a cesarean section, an expensive procedure that can wipe out potential profits and prompt people to abandon the dogs, said Lynnie Bunten, breed rescue chairwoman at the Chihuahua Club of America.
On average, purebred puppies sell for $300 or $400, but Chihuahuas are a lot more common in states bordering Mexico, Ms. Bunten said. Shelters in San Antonio, where she lives, are "brimming with Chihuahuas," and in California, several cities have passed ordinances requiring that Chihuahuas be spayed or neutered in an effort to legislate population control. Some California Chihuahuas have been sent east for adoption. In 2012, for instance, 14 of the dogs were brought to Pittsburgh by a rescue group and quickly placed in homes.
The dogs are also status symbols of sorts: Chihuahuas have served as the Taco Bell mascot ("Drop the chalupa!"), Disney movie stars (think "Beverly Hills Chihuahua") and fashion accessories for the likes of Paris Hilton and Britney Spears, not to mention Elle Woods in the movie "Legally Blonde." When mixed with other breeds, they go by cutesy names like Chugs (Chihuahuas and pugs), Chiweenies (Chihuahuas and dachshunds) and Chi Pins (Chihuahuas and miniature pinschers)
Arizona's Maricopa County, where the shelters take in more animals than any county besides Los Angeles County, is discussing a partnership with one of Phoenix's most popular Spanish-language radio stations, La Campesina, to spread the message that sterilizing dogs "is part of the responsibility of owning a pet," said Melissa Gable, spokeswoman for the county's Animal Care and Control.
The county is also in the middle of a three-year, $6 million campaign to curb pet homelessness, focusing on Chihuahuas, pit bulls and cats, which are the most commonly found (and euthanized) animals in its shelters. ty.
Chihuahuas are jittery by nature, bark often and loudly, and, like most dogs, bite when they perceive aggression, even if the aggressor is a baby grabbing a tail or a paw. They are "little dogs with a big-dog attitude," said Ms. Gable, and it is the failure to understand that sometimes prompts a family to turn them in to a shelter.