When you say horse parasites, what do you mean. There are quite a few "horse parasites". If it's just a type of worms, I wouldn't get too worried. You can just give him some wormer in a couple of doses and be done with it and not have to worry about it again. Most of the time when you worm a dog, even for "dog worms" you should do it twice. Once and then again 10 days later. The breeder you got him from probably just didn't worm him. Most breeders start worming at 2 wk old and worm every two weeks until they leave their place.
Best of luck.
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