The dogs of the Dow. The pet industry is booming in the U.S., expanding at twice the rate of GDP since the Great Recession. A new exchange-traded fund, ProShares Pet Care ETF, that invests in pet-related companies -- everything from pet food to veterinary services -- began trading on Tuesday under the ticker symbol PAWZ, aiming to lure investors who want to bet on the growing sector. It's the second such animal-spirited fund offering to launch this year.