TUESDAY, Feb. 26 (HealthDay News) -- For children with autism, trained dogs may offer not only a furry friend, but some therapeutic benefits, too, a new research review finds.

There is a "substantial body of evidence" that dogs act as "social catalysts," even encouraging adults to be a little friendlier to each other, said senior researcher Francesca Cirulli, of the National Institute of Health in Rome, Italy. And the few studies that have focused on kids with autism suggest the same is true for them.

People have long turned to animals as a way to help with health conditions or disabilities -- either as part of formal therapy or to offer everyday assistance (such as guide dogs for the blind).

In some cases, "therapy" or "service" dogs are called into action to help children with autism spectrum disorders (ASDs) -- a group of developmental brain disorders that hinder a child's ability to communicate and interact socially. ASDs range from the severe cases of "classic" autism to the relatively mild form called Asperger's syndrome.

In the United States, it's estimated that about one in 88 children has some form of autism.

Yet there has been little research into whether trained dogs actually benefit those kids. The good news is, the existing evidence is promising, according to the new review, published in the February issue of the Journal of Alternative and Complementary Medicine.

However, "it is early to draw final conclusions," said Cirulli.

Specifically, Cirulli's team found six published studies of dogs' effects on children with an autism spectrum disorder. Four of them looked at therapy dogs -- dogs that therapists use during formal sessions to help children settle in, get engaged and be more open to communicating.

Overall, the studies were positive, Cirulli and her colleagues found.

In one study of 22 children, for example, kids were more talkative and socially engaged during therapy sessions where a dog was present. In another study, of 12 boys, the children were less aggressive and smiled more when their therapy session included a canine companion.

Two studies focused on service dogs -- trained dogs that live with the family. The animals serve mainly to keep kids with autism safe; when the family goes out, the child will be literally tethered to the dog to keep from running off or getting hurt.

"That can be a huge relief for families," said Dr. Melissa Nishawala, medical director of the Autism Spectrum Disorders Clinical and Research Program at NYU Langone Medical Center in New York City.

Parents' anxiety over their child's safety can lead to social isolation in some cases, noted Nishawala, who was not involved in the study. "Your world can get very small," she said, "because you limit where you go."

So a service dog can make a big difference to the whole family, Nishawala said.

Cirulli's team found that service dogs might also benefit children's behavior. In the two studies they reviewed, parents generally said their children were better behaved and more attentive after the family got a service dog.

There are still plenty of questions, though -- about both therapy dogs and service dogs.

For one, children with an autism spectrum disorder vary widely in the types of issues they have and their severity. No one is sure which kids might benefit most from time with a trained pooch, Nishawala noted.

She said more studies are needed -- not only larger ones, but also ones with better "definitions." That means making sure the children involved have been formally diagnosed with a form of autism, defining what the "therapy" is, and being clear about what outcomes the study is assessing.

There is a lot of anecdotal evidence that a dog could help bring a child with autism out of his shell, said Nishawala, but scientific evidence is just coming in.

Cirulli agreed that better defined studies are key.

It's possible, Cirulli noted, that a dog could have negative effects on some kids with an autism spectrum disorder. An animal might, for instance, increase "hyper" behavior.

For parents wondering whether adopting a dog is a good idea, the answer seems to be, "It depends."

Cirulli pointed out that these studies focused on dogs trained to be around children with autism. So the findings cannot be assumed to apply to your average Fido.

You might first want to see how your child reacts to a friend's or neighbor's dog, Cirulli suggested.

"Getting a dog could be a nice thing for the family," Nishawala agreed. "It could be therapeutic for everyone."

If you are interested in a trained service dog, be prepared for an investment. It costs about $20,000 to train a dog, and the family would have to foot much of that bill.

More information

Autism Service Dogs of America has more on which kids might benefit from a canine companion.