Intestinal Parasites & Heartworm

Internal Parasites (Worms)

Puppies are born with worms — an unappealing thought, but that’s the way it is! The worms that puppies are born with are roundworms (ascarids), although there are other intestinal parasites that can infest puppies: hookworms, whipworms, tapeworms and single-celled parasites called coccidia and giardia. Puppies should be wormed at birth and every two weeks after that, until stool samples show there are no more parasites.

Intestinal parasites must be eliminated because they can weaken young animals and stunt their growth. They can also be passed to humans from the puppies, especially to children. The best insurance you have is to remind everyone around a young puppy to wash their hands after having contact with her — especially after picking up dog droppings.

How to know what parasites your puppy has You cannot know what worms may be in your puppy’s gut without having a stool sample examined by your veterinarian’s office. Bring a stool sample to his first vet visit. Based on what is found, your puppy will receive the necessary treatment.

How do you rid the puppy of worms? Worming medication — which usually consists of a pill or pills — is something that only a vet should give, because it must be specific to the worms that are there. Some intestinal parasites can be treated only by a prescription medication. There are also over-the-counter worming medications, but you wouldn’t want to do that because the product may be aimed at a variety of parasite(s) that your puppy doesn’t have — and therefore would not eliminate the parasites that the puppy does have.

Heartworms are internal parasites that are much better to prevent than to try to treat. It didn’t used to be treatable once a dog was infested, but medical advances have now made it more feasible to eliminate the worm.

This sickness is carried by mosquitoes that pass it to the dog when they bite her. True to its name, the worm can literally get into the heart and kill the animal. However, there are no early symptoms, so you wouldn’t know the dog was infected until it was too late. There are monthly tablets and biyearly tablets — Heartgard is one such brand — that your veterinarian can sell you to protect against this illness. However, there is a newer injectable medication called ProHeart 6, which is given twice a year but that has caused serious (sometimes fatal) reactions in dogs. Many vets have stopped prescribing this treatment — or never even offered it — because of the adverse reactions.

Your puppy is safe for a while if his mother was on a heartworm preventive medication when she was pregnant, which any responsible breeder would have made certain she was.

You can consider having your puppy take preventive medication at the time of his first vet visit, but only after discussing it with your vet and careful consideration. You don’t have to worry about your dog having this illness or protecting against it if you live in an area where there are no mosquitoes (or climate conditions that could attract them).


  1. The dog needs a blood test before taking the tablets to be sure that no infection has occurred — UNLESS the puppy’s mother was on preventive medicine and the puppy was started on the medication by twelve weeks of age. Taking the tablet can kill a dog that has already been infected.
  2. Once you start the dog on medication, you have to give it every month, even during periods when there is no possibility of mosquito activity. If you do stop, you’ll have to have the dog blood-tested before starting the medication again, so it’s easier on you and the dog to just get in the habit of taking the pill year-round if the dog will encounter mosquitoes at any point.
  3. Avoid the injectable medication until it is proven safe.

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Copyright © Tracie Hotchner – Originally appeared in The Dog Bible: Everything Your Dog Wants You to Know by Tracie Hotchner