Dog and cat lovers have a new way to make sure their pets get plenty of exercise and nourishment: phone apps that track how much an animal plays, runs, sleeps and eats. Whistle, an iPhone app and monitor worn on a dog's collar that was launched last week, measures an animal's activity throughout the day. The app can track changes over time and can compare exercise levels with other dogs of the same breed. Created with input from veterinarians, Whistle Labs' app aims to help owners detect early medical problems by showing changes in a dog's activity level and behavior compared to other animals of the same age, breed and weight. "What (veterinarians) get today are hyperemotional responses, often driven by one or two anecdotes," said Ben Jacobs, chief executive of the San Francisco-based company. "What we found out was that a) vets didn't really have the information they needed and b) there's no breed weight and age standards," he added