***EMBARGOED UNTIL 11.00 GMT, TUES FEB 25TH (06.00 ET)*** Video grab of the 'dog fitbit' being tested. See National News story NNpets. A Fitbit-style health tracker for PETS has been invented by British boffins. Pet owners may soon be able to track their furry friends' health by monitoring their heart and breathing rates with a new fur-friendly device. The wearable technology, created at Imperial College <a href=