Mary,
When I took the four ferrets for the vet visit, she gave me "interceptor"
heartworm tablets, and told me to give each ferret 1 pill a month, for 12
months, so here is a second professional opinion.  Yes, as it seems they
take it once a month for 12 months.
 
The new ferrets are adjusting so well, Sugar, who came to us flighty and
aloof, is becoming attached, by following me around the house.  And she is
getting along with the others.  They haven't started giving kisses yet, but
that day will come.
 
Marti
Loosewire, Lucy, Sugar & Spice
[Posted in FML issue 1722]