I'm in Ontario Canada. Unfortunately unless you buy Bruns who have been outcrossed to Champagnes to expand the bloodline then you're not going to find any that are unrelated, they basically are all out of a single pair.
It can be a whole manor of things ranging from intraocular pressure from something like a head injury (a bit of swelling of the brain can cause it). Or Other possibilities might include retrobulbar abscessation (all though rare in general most cases are in NZW). Sometimes although it may seem...
I breed by weight and how mature they seem. Not all rabbits mature at the same rate so it's difficult to say that all commercial breeds are mature at 8 months where as all fancy breeds are mature at 6 months.
I've had commercial does who made senior weight and were mature enough to breed at 6...
Oh boy I feel special :D
My favourite heritage breed is the Argente Brun, they are a recognized breed in Canada and Europe and have been for many years.