For Dr. Jeff Werber, a veterinarian at the Century Group in Los Angeles, there has always been a gap between what he can see in his office and what's really going on with a dog. "The thing is, animals act very differently behind closed doors, when they are alone, than they do around people, especially their owners." Often, Werber says, an owner will notice a dog is limping. But when he examines the animal at his office, it walks normally. "All the adrenaline and the desire to show off overcome the injury."

Whistle, a new gadget that tracks your dog's activity, hopes to solve that problem. It's a small circular device about the size of a watch face that attaches to the dog's collar. It uses an accelerometer to tell if the dog is walking, playing or sleeping. Whistle sells for $99.95, including a companion app and free web service. The unit relies on Bluetooth for the mobile app and Wi-Fi for remote monitoring. Like Fitbit and the Nike FuelBand, it measures daily activity and charts changes in exercise. If there is a sudden change, it alerts the owner, who can share a detailed report with their vet.

Ben Jacobs, the CEO and co-founder of Whistle, has been a dog owner his whole life. "When I was a young, I had a German Shepherd who passed away at five. It's one of those things you never really let go of." He's had stints in tech and finance, working at Rapleaf and Bain Capital before turning entrepreneur. "It turned out my dog died from intestinal issues, which seemed really sudden to us." The inspiration for Whistle was to track the micro-signals, the early warning signs an owner might miss.

"By the time most owners see the problem, it has gotten quite acute," says Dr. Werber. "Dogs are very good at hiding the signs from owners. If you can see a change in activity or sleep, it makes it possible to spot problems sooner, and get them treated with less expensive, more preventative measures."

The company announced today that it has raised $6 million in funding. The round was led by DCM Ventures; Jason Krikorian, a general partner at DCM and co-founder of the company behind the Slingbox television place-shifter, will join Whistle's board. "There are more dogs than children in the US, and we spend over $50 billion a year on pets," said Krikorian. "Bringing a suite of smart products to the space is an extraordinary opportunity."

There are competing products on the market, like the Tagg tracker from Qualcomm, but they are focused primarily on your individual pet. Whistle not only shows the average weekly routine for your dog, but compares that to the activity of dogs of the same weight and breed, so owners can tell if their pooch is keeping up with the pack. "This is going to create a pretty incredible data set," says Werber. "It's the kind of big picture we just haven't had access to before." Currently Whistle is being tested across several hundred dogs from all major breeds. Whistle has partnered with the Veterinary Center at the University of Pennsylvania to collect data from dog owners and conduct a long-term study on canine health.

Tatiana Turan owns Zoe, a three year old Lab-Pitt mix, and has been beta testing an early version of Whistle. "I'm a pilates instructor and dancer, so I am a little bit paranoid about making sure she gets enough exercise." Whistle was able to show Turan how much Zoe walked, played, and rested. After a few weeks of using the device, Turan noticed a surprising pattern. "We saw that Zoe was getting a lot less activity on Friday and Saturdays. My husband and I both work those nights, and we just hadn't realized how much it was impacting her." The couple extended Zoe's morning walks on those days to get her level of exercise back up to normal.

Overweight pets live, on average, two and half years less than their healthy peers, and in America, more than half of dogs and cats are considered overweight or obese. The extra weight can lead to a litany of health conditions, including diabetes, high blood pressure, arthritis, and kidney failure. Dog owners can expect an average of more than $600 a year in bills from the vet, and that number increases for dogs in poor health.

Dr. Werber hopes having activity data on hand will help to confront another common problem for vets: pets' owners. "A lot of the time, if the dog is obese, so is the owner. Many vets are embarrassed to say the dog is getting fat if the the owner is too. But when you have the data right in front of you, telling the story of a decline in activity, that makes it much easier."