Toxicology Brief: Proper Use of Ivermectin in Cats
Ivermectin was sold commercially on the international market in 1981 and was licensed for sale in the United States in 1983.2 The drug was approved as a feline heartworm preventative in 1996.3 Ivermectin has proven to be a very valuable drug to veterinarians in that when given at the appropriate preparation and the recommended dosage, it has a wide margin of safety in all sizes and breeds of cats.
I’m pretty sure it is what we used for our cats years ago. The price at that time was relatively high because you paid for an equivalent amount, or so, which was sent to Africa to combat river blindness.