We got a dog and then trained him as an emotional support dog for our daughter with ADD and anxiety. He has helped her so much thrse past 6 years!
If you saw your son interactive so positively with a dog, I’m sure it would make a big difference in his life to have one!
Also, there are all sorts of dogs. You could get one that doesn’t shed and hypoallergenic. Our dog doesn’t shed much and he’s a cocker/chihuahua mix.