Besides ivomec/Heartgard there are 2 other heartworm preventative options. Interceptor, the brown 0-10 pound dog size, can be used. It is given once a month orally. The other option is Revolution. The 5-15 pound cat size can be used. This is applied once a month over the shoulder blades. I also use the Interceptor tablets for my ferrets. They both will actually eat the beef flavored tablet on their own. Hope that helps, Jerry Murray, DVM [Posted in FML issue 3625]