The wearable computing craze went to the dogs on Wednesday with startup Whistle introducing a smart pendant that tracks physical activity levels and sleep patterns in canines.

"Whistle was inspired by my love of dogs," co-founder and chief executive Ben Jacobs told AFP as his pooch, Duke, darted about a dog park near the company's office in San Francisco.

"We're introducing a window into their lives; creating a way for owners and veterinarians to take a preventative approach to our pets' health."

Whistle devices attached to dog collars or harnesses use movement-sensing accelerometers to track activity and even how well a pet is sleeping, then relay the information wirelessly to smartphones or Wi-Fi hotspots.

An online database built in collaboration with researchers and veterinary groups allows individual dog activity patterns to be scrutinized for hints that something may be amiss.

"You see this desire to take good care or our pets, but no information," Jacobs said, noting that dogs typically hide discomfort in an eagerness to please humans who have their devotion.

"We talked to veterinarians and found out there is no way to get that information other than to build the hardware."

Whistle Activity Monitors may be ordered online at whistle.com for $100 and deals are in the works to make them available in major US pet store chains. Orders were to ship by September.

Data collected by the devices is fed to a free application tailored for Apple mobile devices. A version of the app will be released for Android-powered gadgets later this year, according to Jacobs.

The software compares dog activity data to norms based on factors such as breed, age, and weight, and also watches for deviations from patterns established for individual pets.

"A dog's number one indicator of health is their activity relative to their baseline," Jacobs said. "You can alert dog owners to changes in behavior much earlier, and getting vet treatment early can save lives and money."

A version of the Whistle application designed in collaboration with veterinarians is designed to provide detailed activity information for evaluating pets.

Meanwhile, the pet owner version of the application lets them know things like how often a dog may have been walked while left in the care of children or if the canine romps about each day when mail is delivered at home.

About $60 billion is spent annually on pets in the United States, with a third of that going to medical care, according to market figures cited by Whistle. There are approximately 80 million dogs in the United States.

One of the Whistle co-founders is a cat lover, making it likely an activity monitor will eventually be tailored for felines, according to Jacobs.

"I think the human quantified-self movement and the wearable computing movement will converge into one mega-device for the millennium, probably our phones," Jacobs said.

"These guys will never have phones, so that requires a separate set of products."

Whistle on Wednesday that it is getting $6 million in funding from investors including DCM Ventures.

"There are more dogs than children in the United States," said DCM general partner Jason Krikorian, a co-founder of Sling Media and new member of the Whistle board of directors.

"Bringing a suite of smart products to the space is an extraordinary opportunity."