Even though fleas and ticks are not spaghetti-like worms, some drugs in the ivermectin family will kill fleas, ticks and ear mites. If the heartworm medication is not effective against fleas and ticks, it will be combined with flea and tick preventative to create a single once-a-month parasite medication that prevents against both internal and external parasites.
https://www.amcny.org/blog/2022/03/30/ivermectin-an-important-veterinary-medication/
