When bringing the fox into Maya, we realised we had a problem. The areas around the character on the UV, not covered by the character were rendering out black (see below).
I showed this problem to Alec. He informed me that Arnold does not render out alphas as transparent. Instead, you have to create you own opacity mask and put it into the material, with the other maps.
To create this mask, I would have to create a clipping mask over my original fox UV, block it out with white and then add a black background (see below).
This mask was then placed into the opacity node under the refraction settings in the material. Thankfully it worked, creating a clear character.
Below is the test character and the second character is a knit texture as a normal map on the character.