Downward-facing dog is no long just for humans! Introducing dog yoga, or doga, the latest craze of yoga where your pets are welcome.

What began with just a few studios in the early 2000's has grown into a big business across the U.S. and many Asian countries.

Doga combines massage and meditation with gentle stretching for dogs and their human partners.

Instructors argue that dog yoga is a great way to build up a spiritual connection between you and your dog. Because dogs are pack animals, they say the animals are a natural match for yoga's emphasis on union and connection with other beings.

Yet, not everyone is so enthused about the doggy classes.

Doga runs the risk of trivializing yoga by turning a 2,500-year-old practice into a fad, Julie Lawrence, 60, a yoga instructor and studio owner in Portland, Ore told the New York Times. To live in harmony with all beings, including dogs, is a truly yogic principle. But yoga class may not be the most appropriate way to express this.

Also, there is no complete training course for doga instructors - though seminars do exist.

Like it or not, have a look below to peek in on some of the world's top doga studios: