From the reading that I did when my ferret had a Chordoma, it doesn't seem to cause them any pain. My ferret, Rio, didn't seem to be bothered by the tumor. If the chordoma is on the end of the tail, it could probably be left alone. However, there is always the risk that it will continue to grow and/or move up the tail to the spine. A Chordoma on the spine could cause problems. Based on that information, as well as on discussions with my vet, I chose to have the tumor removed. A quick search today on Chordoma brought up a link to the following article provided by Dr. Bruce Williams: <http://www.smallanimalchannel.com/media/ferrets/ferret-health/tumors-in-ferrets.aspx.pdf> Inez [Posted in FML 7315]