I adopted a dog once long ago that had heart worms. GSD that had to go thru the heartworm treatments. She eventually died an old dog but with cancer. Since this dog, my dogs have been heartworm meds once a month. I’m not sure of how safe they are and actually have my doubts about big pharma dog meds. The pills have gone up in price too to where they are not affordable to a lot of folks. There is not any relief in site either according to my vet. The prices are not going down and generics are not availableHeartworm is another good example. We didn't lose any dogs to Heartworm growing up in Oklahoma, nor any since in Oregon now that they are on Heartworm medicine.