Our old girl (Tawny) went for her heartworm checkup and she always gets the 1 pill a month treatment (treats to her, she'll eat anything) They told us about the new 6 month treatment but with a side bar, once its injected they can't take it back. I was glad to here them warn us. At our vets they seem to tell us everything and then let us know the experiences they have had. It helps me have confidence in them knowing they want to do the best for my doll.