Administer the medication orally once a month for a whole year for the treatment of roundworms. Over dosage may cause symptoms of disorientation, tremors, lack of coordination, and blindness. In cats weighing 5 pounds or less, the usual dosage is 55mcg. If the cat weighs between 6-15 pounds, a dosage of 165mcg would be required. Make sure the cat does not merely swallow the chewable tablets. In cats, heartworm infestations can be prevented by administering a dose of 0.012 mg per pound once in a month. Ensure completion of treatment, as there are chances of relapse if otherwise. The ideal time for administration is the mosquito season when the heartworm larvae are active in mosquitoes.