I had 2 litters of standard rex rabbits. Around the age of 8-10 weeks I had a few of my bunnies develop a lump on their ear, got larger, got uglyish. Went to the vet, a fine needle aspirate later and the result of a fatty/fiberous mass. still not knowing what that meant I had one of the masses removed and biopsied. Results came back as a fibrosarcoma and result of Shope fibroma virus infection. Attached are a photo journal of one of the bunnies (will attach photos of resolving lump as that transpires) and a link to an article from the Michigan Department of Natural Resources detailing the virus. It was very disconcerting to me but basically it is a self resolving, self limiting, vector born virus that does not affect the viability of the rabbit. After working pretty hard for some answers on this, I thought it might be nice to share with others.
article: http://www.michigan.gov/dnr/0,4570,7-15 ... --,00.html
photos: https://www.facebook.com/anbriarrabbitr ... 2786195091
article: http://www.michigan.gov/dnr/0,4570,7-15 ... --,00.html
photos: https://www.facebook.com/anbriarrabbitr ... 2786195091
