Remember not all parasites are intestinal or heartworm related. And not all anti-parasites work on all types of parasites.
Always focus on strengthening the immune system through fresh foods, herbs, essential oils and supplements. One thing we should target at least 2x per year is blood-bourne parasites, microbes, bacteria, etc.
One Option is NHV Blood Parasites with Nutritional Support:
Follow instructions as directed from NHV
Also visit the Essential Oil Section for additional protocol suggestions