I used LDN for the late stage lyme disease I live with. 3 mg a day. Naltrexone at high doses is used to help drug addicts through withdrawl. The premise behind LDN is you take it at night because our immune systems rejuvinate then, and it is supposed to cause the immune system to kick in to high gear. For me, I did not see any benefit. At all. I used it for a year. I know many people with auto immune diseases, particularly lupus and MS who use it and it helps them tremendously. I don't think there is any drug that is "harmless", nor have I read any information on using it for pets. Finding the correct dose would be important. For example, MS patients are never to take more than 1.5 mg. I started at that and worked up to 3 mg, but I was unable to sleep at that level and had to go back down to 1.5. I know others who felt terrible while on it, that's why I would never say it is harmless. I surely would not know the dose for a ferret, and would be careful with the whole thing. But there is a LDN website with alot of information. http://www.lowdosenaltrexone.org/ Mary in Virginia [Posted in FML 7542]