Discontinue the use of macrocyclic lactones as a «slow kill» protocol for known heartworm infections; it is NOT recommended by the American Heartworm Society. (heartwormsociety.org)
Any method utilizing only macrocyclic lactones as a slow - kill adulticide is not recommended.» (oregonvma.org)
a. Administer macrocyclic lactone preventive drugs to dogs greater than 6 weeks of age prior to relocation.1 (heartwormsociety.org)