Actually A/D is a high protein and a high fat food.  The reason it says
only 8.5% crude protein is because it is 78% water.  You have to convert
to a dry matter basis to compare it to other ferret foods.
 
A/D is fine to feed to ferrets short term and even long term to help
insulinoma ferrets.  However for a ferret with chronic kidney failure,
you do want a "low protein" diet to help prevent nausea and anorexia.
 
Eukanuba has a multistage kidney diet for cats.  I would suggest feeding
that along with your regular ferret food.  Unfortunately we do not have a
ferret "Kidney Diet," nor do we know exactly what protein level would be
low enough to help.  The other problem is if the protein level is too low
then we create other problems.
 
Hope that helps,
Jerry Murray, DVM
[Posted in FML issue 3408]