My neighbours dog keeps chewing up my son's footballs. Is there any sort of coating that I can put onto his next football to stop that dog from chewing it up?
There isn't anything you can put on the ball without making it unuseable as a football. Garlic might actually make the dog go for it more (my dogs love garlic and would quite happily through anything with garlic on). The best bet would be to ensure the ball doesn't go onto your neighbours properly (if that is the case, if not have a word with your neighbour).
Are you saying that your neighbour's dog comes into your garden and chews the football or that your son kicks the ball into your neighbour's garden?
If it's the first, then ask your neighbour to adequately fence his garden against the dog escaping.
If it's your son kicking the ball over then he is the one who needs to be told to keep the ball within your own property. You can't blame the dog for playing with a ball that suddenly appears in his space!