Apparently I come up on the internet for Appa costumes for dogs. Imagine that. :) Anywho, I have actually gotten a few requests to have one made for "insert person here"'s dog. So, I was thinking that potentially I could make a few (a very limited number because these are time consuming) for dogs.
Below is a diagram (modeled by Pudge derPoopster) of the dimensions on said dog that I would need.
Click to enlarge to read.
If you decide you want to commission me for an Appa costume, please drop me a line at firstname.lastname@example.org. :)