Pipi's eyes bulge fiercely when strangers approach the Chihuahua in the cramped clothing store where her owner works.
But Pipi doesn't bark. She never barks. She never will.
Her owner, Chen Sheng-hua, suspects that the rescued stray's vocal cords were snipped.
"When she opens her mouth, nothing comes out," Chen said.
Animal rights activists say they frequently find mute dogs that apparently have been dumped by illegal breeders, who are having trouble selling animals in Taiwan's slow economy.
In a crowded place like this, where most people live in apartments or densely populated towns, unlicensed breeders are tempted to cut dogs' vocal cords to keep them from disturbing others and attracting the attention of authorities, activists say.
"The mute-dog problem is like the stray animal problem, a result of wrong policies," activist Shen Jung-chen said.
Animal rights groups say authorities waited too long before taking steps aimed at holding down a big rise in the number of stray dogs, such as neutering and registering animals.
Activists have also criticized people for buying cute little dogs, then dumping them when they grow big or old.
Veterinarian Chen Chia-chun says it's extremely rare for dogs to be born mute. He suspects that Pipi lost her vocal cords in a new surgical procedure that doesn't leave a scar.
"In the past, operations to remove a dog's vocal cords left a mark on the outside of the animal's throat," he said. "But now vets go straight into its throat through the mouth and remove the vocal cords from the inside."
Chen says he was asked by phone to perform such an operation once, but turned it down.
The vet says it's not always breeders. Sometimes people pick up strays, but then neighbors complain about the noise, leaving the new owners with the choice of either dumping the dog on the street again or silencing it.
However, Shen, the animal rights activist, argues that private breeders are responsible for nearly all cases rather than traditional pet owners.
Individuals begin breeding dogs at home for profit, Shen says. But because they fear that neighbors will complain to police, the breeders have the animals' vocal cords cut. If the illegal breeders think that capture is near, they dump the animals in the streets, Shen says.
"Only about 30 out of 300 private dog breeders are registered," Shen said, adding that pushing for their compulsory registration is one of her group's priorities.
In an isolated valley south of Taipei, the air is thick with the smell of feces produced by about 850 dogs living in a shelter run by volunteers. There are rows of cages, some sheltered by corrugated metal roofs.
Pairs of muddy dogs share each cage, and most of them begin barking as soon as they see visitors. Mutts are mixed in with purebreds.
One volunteer, Yang Hsiang, says that out of the 500 dogs she's responsible for, more than a dozen are mutes, including four that were picked up together. There could be more, but finding them is difficult because they're drowned out by the deafening barks of hundreds of dogs.
One of the mutes is Nana, a shepherd mix with long ears and long bushy tail. She succeeds in uttering a sound, but it's only a hoarse croak, not the bark or yelp of a big healthy dog.
Yang is worried about the dogs because their numbers continue to multiply while donations are dwindling. Many Taiwanese are reluctant to euthanize dogs because it violates their Buddhist beliefs.
"The people who bring the dogs are also responsible for paying for the food," she said. "But as Taiwan's economy has gone into decline, donations are drying up."