If they are introduced European rabbits, like in the San Juans, season is open year round. BTW, I would not worry about what the liver looked like, unless you eat the liver. I have eaten a lot of rabbits (European here and cottontails in WI) and have never had a diseased rabbit.
Tularemia is the only disease I know of that you would need to worry about, you can wear gloves when butchering, and cooking kills it off.
Tularemia, or rabbit fever, is a bacterial disease associated with both animals and humans. Although many wild and domestic animals can be infected, ...
www.idph.state.il.us/public/hb/hbtulare.htm