A Canadian city has declared Molly, a three-pound (1,361-gram) teacup chihuahua a "dangerous dog" and ordered her muzzled after the dog bit a postal worker, local media said Thursday.

"I don't even know if they have muzzles that size. I just think it's kind of silly, to the extreme," Molly's owner Mitzie Scott told PostMedia News. "The dog is literally three pounds -- it's the size of an adult shoe."

The controversy erupted after Molly, 5, bit a mail carrier's ankle in August after escaping through an open gate at Scott's Windsor, Ontario home.

That meant under a city bylaw that Molly must be registered as a "dangerous dog" and the owners would have to obtain a million-dollar liability insurance policy for their dog, muzzle Molly and keep her on a leash at all times.

The city also ordered the family to put up signs at the doors of their home which read: "Warning: Dangerous Dog on Premises."

Scott appealed to the city's licensing commission to have the designation overturned, but was turned down. Any dog that causes injury to a person or a domestic animal in most Canadian cities must be registered as dangerous.

The mail carrier was prescribed an antibiotic cream by her doctor for the injury -- four small puncture wounds.

Windsor meanwhile now has a total of 24 dogs on its dangerous dog registry, including another chihuahua -- one that weighs eight pounds.