A service dog could go to school with him unlike a pet cat. A service dog could be a great help but remember the dog needs to be trained and cared for. A dog may need training reinforcements throughout the day at times and also if the dog has to go out during the day someone has to take it. The school may not be able to deal with it unless your nephew has a one-on-one aide or is able to care for the dog on his own. Wow, it seems like your nephew is dealing with a lot.