http://www.smartgroups.com/message/readmessage.cfm? gid=1423922&messageid=9762&startid=9766 No need to waste a lot of money to "test the mosquito." Lets start your ferrets on a heartworm preventative (ie Heartgard, ivermectin, Interceptor, or Revolution). They actually work by killing any 'new heartworms" (Larva stages) that your ferrets were exposed to during the past 30 days. Thus it would cover this mosquito bite. It takes roughly 6 months after the mosquito bite before the heartworm test (Idexx snap Elisa test) will detect the heartworms (adult stage in the heart). Hope that helps, Jerry Murray,DVM [Posted in FML issue 4591]