Spring 2011 Magazine

Casa Canine



Parasitic Worms in Dogs: Part 1:
Hookworms, Roundworms and Whipworms

By Deborah Schildkraut, Ph.D.

Dogs get parasitic worms all the time. They are scary-looking creatures and even the thought of them grosses us out. Yet it isn't their looks that should strike fear: it's what these parasites are doing to your dog's health, and possibly your own. A basic understanding of how these worms affect your dog will better enable you to treat and even prevent infestations.

A parasite is any organism that lives off of another organism (the host), with no benefit to the host. Parasites can feed, mate and lay eggs in or on the host. They take nutrients from the host to the detriment or even death of the organism. Your dog is the host and the worms are the parasites. In some cases, people can be hosts for these worms.

Parasitic worms survive by living in various places in your dog's body and feeding off of your dog's organs, blood or nutrients. Three parasitic worms commonly found in dogs' intestines are roundworms, hookworms, and whipworms. Since all three of these worms affect the intestines they show some similarity of symptoms including lack of energy and anemia, mucus or blood in stools, decrease in appetite, bloating, vomiting or diarrhea. Yet, knowing the species and life stages of the specific worms are important in the treatment to rid your dog of worms. The eggs, larvae (middle stage of development) and adults may live in different places in your dog's body at different times in the life cycle of the worm. Worming agents do not kill all species of worms. Nor do they eliminate worms at all stages of development. Fecal testing of stool samples by your veterinarian as well as visually monitoring stools for the presence of worms will help in deciding upon the most affective course of treatment.

So how does your dog get these worms? What are specific symptoms? What kinds of treatments are available if your dog does have worms? How can you prevent recurrent infestation and transmission of some types of worms to the people in your family?

Roundworms dwell in your dog's intestines. They are large whitish worms that can grow to 4 - 8" in length. The adult roundworms feed from the food in your dog's intestines. Your dog gets roundworms from eating the roundworm's eggs. The eggs are found in infested rodents and soil. Symptoms may include anemia, lack of energy, poor appetite, bloating, vomiting, blocked intestines and even death. Roundworms may be coughed up or seen in the stool of an affected dog. Roundworms are more dangerous to puppies as the roundworm larvae can travel via the bloodstream to the liver and lungs leaving a wake of serious diseases such a pneumonia and hepatitis. Puppies can become contaminated via the placenta or milk of an infected mother.

Roundworms can be transmitted to humans where they can cause serious problems for children. Roundworms eggs are passed out your dog's body in your dog's stool. The eggs can live for years in soil and sand. Ways to prevent contracting roundworms include keeping the area in your yard where your dog poops separate from where your children play. Wash vegetables grown in your home garden before eating them. Practice common sense hygiene by using disposable gloves when cleaning up stools. And remember to wash your hands afterward.

Even if you aren't seeing worms, your dog may still have roundworms. Take a fresh fecal sample to your veterinarian as part of a routine wellness visit, or if you see worms or other symptoms. Roundworm infestations can be easily treated with an appropriate oral wormer.

Hookworms are bloodsuckers. They are arguably the most common intestinal parasite in dogs in the United States. Their mouths have multiple sets of tiny hook-shaped teeth with which they attach to your dog's intestinal wall. Your dog picks up hookworms from ingesting larvae that live in the soil. They can also enter by burrowing through the skin. The larvae migrate to the small intestines where the worms feed, mate and lay eggs. The eggs pass out via the dog's stools and re-infect the environment.

Throughout the day, hookworms feed by moving from place to place along the intestinal wall. Blood loss occurs as the worm feeds. In addition, every time the worm moves, blood is lost from the spot where the worm was previously attached. In cases of severe infestation this can cause anemia and even death - especially in puppies. Puppies are often born infested. Hookworm larvae can pass through the placenta and the milk of an infested mother. In addition to anemia, symptoms of hookworm infestation include weight loss, black, tarry stools, and lack of energy. They can cause pneumonia in puppies. Because hookworms can enter through the skin, they can cause hookworm dermatitis. Lesions occur where the hookworm larvae enter the skin. Lesions are usually seen on the feet or areas of the body that come in contact with the ground. These lesions are often itchy causing dogs to lick their feet.

Because hookworm larvae penetrate the skin, humans can pick up the worms by walking bare-footed over infested soil. Use common sense hygiene and wear shoes in infested areas. Do not let children play in infested areas.

Hookworms are difficult to see with the unaided eye. A fecal test is necessary to determine if the worms are present in your dog. Hookworm infestations can be easily treated with an appropriate oral worming agent.

Whipworms, as their name suggests, have a long whip-like appearance, tapering from the tail to the head end. They imbed themselves into the wall of the large intestines where the adults feed by sucking blood. They lay eggs that are shed in the dog's stool. The eggs re-infect the dog's environment.

Like hookworms, whipworms are tiny and a fecal test is required to see if your dog is infested. Unlike hookworms and roundworms, they are not transmitted to puppies via the mother. But puppies may get whipworm from ingesting eggs from the soil.

Symptoms of whipworm include bloody stool, anemia, dehydration, lack of energy and weight loss. The quantity of blood that whipworms ingest is small. However, the irritation at the sites where the worms bury into the intestines can become irritated and inflamed, causing diarrhea. If your dog has diarrhea that is treated with an antibiotic and goes away, only to re-occur, it might be a whipworm infestation. Antibiotics will not kill whipworms. Take a fresh fecal sample to your veterinarian for testing. Whipworms are a bit trickier to eliminate than other worms. Your veterinarian may recommend a worming agent given over several days, and at regular times thereafter.

Tips for keeping your dogs and family healthy and parasitic worms under control include:

  • Fecal testing your dog twice a year to keep intestinal parasites under control.
  • Using preventive measures such as a low-dose, once-a-day worming agent if your dog lives in an area with a moist soil yard or a kennel with a dirt run.
  • Common sense sanitation and hygiene including regularly picking up dog waste from your yard, using disposable gloves when cleaning up feces, keeping the area where your dog defecates separate from where your children play, wearing shoes in areas where worm eggs or larvae may be present, and washing home grown vegetables before eating.

If you are still with me, I congratulate you. Parasitic worms are gross. But your effort in reading this column to the end will help you keep your dog and your family healthy and the worms under control.

Stay tuned next time for Parasitic Worms in Dogs: Part 2 - Heartworms and Tapeworms. Yuck!



Deborah Schildkraut, Ph.D. is a writer and columnist for PETroglyphs and an author of children's books about dogs. She lives with her husband and her two canine companions, Gus and Etta.

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