I am a ferret veterinarian,and have been reading that many people are using the new chewable feline heartworm preventative on their ferrets, giving them 1/2 tab monthly. I have contacted the manufacturer on this issue for my own clients, and would like to share my findings: Apparently the distribution of ivermectin in the palatable base is not necessarily uniform. In other words, by breaking the tablet, one ferret may receive the entire dose of the pill, and another ferret may receive none. The chewables, I've been told, are designed to be given as a total tablet for accurate dosing, and therefore, unless your ferret weighs 5 lbs. or over, are not acceptable for ferrets. I am still using the 60 mcg canine nonchewables in my patients. Less convenient I know, but safer and more effective. ( For nonchewables give 1/2 tab per month by mixing with a few drops of Ensure or Ferretone,etc..) [Posted in FML issue 1876]