Identification and Prevention of Worms in Dogs



Did you know that your dog may have worms even though you see no evidence of them?

With the exception of tapeworms, which may be accurately diagnosed visually, the very best way to diagnose worms in your dog or puppy is to have your veterinarian perform a fecal exam. Your veterinarian will examine your dog’s feces under a microscope for the presence of microscopic worm eggs. It is possible however, for your dog to have worms, yet show no eggs in the stool. For this reason it is extremely important to deworm your dog regularly with an effective wormer.

Common Types of Worms:

Roundworms – The most common parasite of the digestive tract in canines and especially common in puppies – are several inches long, look like spaghetti, and may be seen in the stool or vomit of an infected dog. Usually though you will not see them. Adult roundworms live in the intestinal tracts of the dog, consuming that dog’s food. Adult dogs get roundworms from ingesting roundworm larvae, usually from contaminated soil or infected prey, such as a mouse or other small mammal. Many puppies are born with roundworms after contracting them from their mother’s uterus during gestation. Nursing puppies may ingest roundworm larvae from their mothers’ milk. Once ingested the larvae make their way to the dog’s liver. While developing into adult worms, they travel to the lungs, are coughed up by the dog and then swallowed. The adult roundworms live in the dog’s intestines. Their eggs are shed in the dog’s stool and the life-cycle is repeated.

Symptoms include diarrhea, vomiting, pot-bellied appearance, coughing (dogs may cough up or vomit worms), weight loss and dull hair coat. However many dogs will show no signs of infection initially.

Hookworms – Another relatively common type of intestinal parasite infecting dogs and puppies. Hookworms are very small and virtually impossible to see in your dog’s stool or vomit. Adult dogs get hookworms from contact with contaminated soil that contains hookworm larvae. The larvae may enter the dog by burrowing through the skin or feet when a dog is lying on the ground. The dog may ingest the larvae after contact with contaminated soil, often when grooming. As with roundworms, nursing puppies may ingest hookworms’ larvae in their mothers’ milk. Many hookworm larvae develop into adult worms in the small intestine, but some travel to the lungs, become coughed up by the dog and then swallowed (similar to roundworms). The adult hookworms live and mate in the dog’s small intestine. Their eggs are released into the environment via the dog’s feces. The hookworm eggs develop into larvae and the life-cycle is repeated.

Symptoms of hookworm infection include pale mucus membranes and weakness (due to anemia). Some animals will have diarrhea and/or weight loss. Many dogs will show no signs of infection at first. Hookworm infection can be very dangerous to young puppies due to the amount of blood loss that can occur.

Whipworms – Whipworms are even smaller than hookworms and live in the large intestine, where it bites the tissue and embeds its head inside. Like the hookworm, the whipworm sucks the host’s blood for sustenance. Whipworms are rarely seen in the dogs feces. One end of the worm’s body is very wide, while the rest tapers off to a narrow, whip-like head, hence the name "whipworm".

Dogs get whipworms from ingesting eggs that live in the soil (typically ingested through self-grooming). The whipworm eggs pass through the upper GI tract and hatch into larvae in the small intestine. The larvae move down to the cecum or large intestine. It is in the large intestine where they develop into adult whipworms, living and reproducing in the large intestine. Their eggs travel to the environment with the dog’s stool. Whipworm eggs can lay dormant in the soil for years until consumed by a new host, thus repeating the life-cycle.

Symptoms of whipworm infection may not be present at first. Typically, bloody diarrhea will develop as the infection worsens, possibly leading to chronic bloody diarrhea. Anemia is possible, though not as common with whipworm infection as it is with hookworm infection. A whipworm infection can also become severe enough to cause an electrolyte imbalance that mimics Addison’s disease.

Tapeworms – Tapeworms are intestinal parasites that commonly affect dogs. They are long, flat (tape-like) worms that attach to the small intestine of their host. A tapeworm body is several inches long but consists of multiple segments that grow onto the head and neck of the worm. Each segment has its own reproductive tract.

Dogs get tapeworms from ingesting fleas or from eating infected prey. When flea eggs hatch, they consume flea dirt and debris. If present, they will also consume tapeworm eggs. The larval fleas develop into adults as the tapeworm eggs develop inside the fleas. Adult fleas jump on a host (usually a dog or cat). The host chews itself and consumes the adult flea, then the developing tapeworm is released into the dog or cat. The young tapeworm attaches to the small intestine and grows segments. The end segments are basically egg sacs which eventually detach and make their way out of the dog or cat’s rectum into the environment. The tapeworm segment, which resembles a grain of rice, breaks open and the eggs are released. If flea eggs are also present in the environment, the life-cycle is repeated.

Generally tapeworm infection does not tend to adversely affect dogs.

Zoonosis Information – Humans can contract roundworms through contact with contaminated soil, potentially leading to a serious condition called Visceral Larva Migrans. Always wear gloves when handling any soil, especially that which may have come in contact with dog feces. Children are at an especially high risk. Humans can contract hookworms through contact with contaminated soil. Hookworm larvae can penetrate the skin, potentially leading to a relatively minor but rather uncomfortable condition called Cutaneous Larva Migrans. Avoid walking barefoot in areas where pets may have once defecated (including beaches). Children should not play or sit in areas where pets may have once defecated. Fortunately, the type of whipworms that affect dogs is rarely transmissible to humans. However, precautions should still be taken to prevent contact with dog feces or contaminated soil. The type of tapeworms that affect dogs is not directly transmissible to humans, however, tapeworm infection can be transmitted to humans by accidental ingestion of a flea.

Treatment – Medications containing the active ingredient Pyrantel Pamoate are effective in the removal of round & hookworms. They do not remove whip or tapeworms. Examples of these medications are D-Worm (chewable or non-chewable), Nemex-2, Sentry WormX DS and Evict Liquid Dewormer.

Medications containing the active ingredient Fenbendazole are effective in the removal of roundworms, hookworms, whipworms and the type of tapeworm caused by ingesting infected prey. (It does not kill the type of tapeworm caused by fleas). Safe-Guard Canine Dewormer is one example of this comprehensive dewormer.

Medications containing both Pyrantel Pamoate & Praziquantel are effective in the removal of roundworms, hookworms and both type of tapeworms. It does not remove whipworms. Examples of this type of medication would be Sentry WormX Plus and D-Worm Combo.

Medications containing Praziquantel are effective in removing both types of tapeworms, however are not effective in removing other intestinal parasites.

Renee Jones-Lewis, CPDT-KSA, is a certified professional dog trainer, having received instruction from canine behaviorist Dr. Pamela Reid, plus nationally acclaimed trainers: Patricia McConnell, Pia Silvani, and Jean Donaldson, to name a few. She serves as a Pet Marketing and Canine Specialist for JeffersPet and

Questions about this article, training or non-emergent health concerns are welcome. Renee can be reached most days from 9am – 5pm Central Time (Mon-Fri) at 1-800-533-3377 (JEFFERS) ext 381 or by email rsjones@jefferspet. com.

Information given here is meant to be helpful and/or educational. It is in no way intended to supersede, challenge or supplant the diagnosis, treatment or advice of a licensed veterinarian.

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