Pet dogs can have a positive impact on children with autism and bring them much-needed companionship.

The most effective autism treatment may come on four legs, according to a University of Missouri study on the relationship between pet dogs and children with autism spectrum disorder (ASD).

Research fellow Gretchen Carlisle of the Research Center for Human-Animal Interaction in the University of Missouri College of Veterinary Medicine surveyed parents about their families’ experience with dog ownership. The research, published in the Journal of Pediatric Nursing, highlights some of the most rewarding aspects of dog ownership for children with ASD (as well as some less favorable ones).

“Children with autism may especially benefit from interacting with dogs, which can provide unconditional, nonjudgmental love and companionship,” Carlisle said in a press release.

Their dispositions vary by breed, but dogs’ friendliness and loyalty make them excellent companions for people with and without disabilities. The perceived benefits of dog ownership, chief among them comfort, friendship, and responsibility, played a significant role in parents’ decision to bring dogs into their home.

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Of the families of children with ASD surveyed, 67 percent owned dogs and 94 percent of parents in those families reported a bond between their dog and their autistic child. Many parents reported positive experiences of dog ownership.

“We just really all love dogs and yes, it is a comfort thing for all of us,” one parent said. “She [the dog] just really adds a lot to our house.”

Autism doesn’t manifest in the same way for every person, but verbal and social disconnects are common hallmarks of the disorder. Because this behavior might appear strange to others (especially to other, less understanding children), communication can be a challenge. But animals like dogs lack the facial expressions and social cues that make human interaction so intricate, as so fraught with anxiety for some children with ASD.

“If the child with autism does not have good language skills, dogs communicate very well without language,” said Dr. L. Eugene Arnold, M.Ed., a psychiatrist at the Nisonger Center at Ohio State University’s Wexner Medical Center in Columbus.

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In her report, Carlisle cites “attachment theory” as an explanation for why dogs, in particular, make such good companions for children with autism. The theory, which was originally applied to the bond between mother and infant, has since been expanded to include the connections formed among other family members. Carlisle proposes that dogs can also be a source of healthy attachment for the children who love them, interact with them, and form bonds with them.

The bond between species goes much deeper than entertainment and affection.

“This is clearly more complex than just comfort,” said Dr. Eric Hollander, Director of the Compulsive, Impulsive and Autism Spectrum Disorder Program at Montefiore Medical Center in New York City. “While children with autism may become attached to stuffed animals which provide them with comfort, animals can be sensitive to subtle changes in emotions in humans and react in a way which provides protection or support or comfort.”

The survey responses from parents support this theory.

“[T]here’s something about being with an animal that maybe you can’t get anywhere else,” one parent said. “I mean, you can stroke a dog and you don’t have to tell them all your stuff, but you just feel understood in a nonverbal way. They can sense a lot of things about you, like if you’re sad.”

For all the advantages of dog ownership, various downsides were also reported. Every child’s experience with autism is different, so dog ownership was not a success across the board.

While some parents saw the chance to instill responsibility in their children through dog ownership, others saw a burden. The expense and time involved in caring for a dog was too much for some parents and their families to handle.

Sensory issues, especially sensitivity to sound and touch, sometimes outweighed the emotional benefits of dog ownership. Some parents whose families did not own dogs reported that dogs could be too loud for their children, or that their children did not like the feeling of the fur on certain dog breeds.

Canine companionship is just one way of coping with the symptoms of autism spectrum disorder, Arnold cautions. “It should be part of an overall program that’s sensitive to the child’s development and promoting their various needs,” he said.