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Intestinal Worms: The Basics

hookworm in dogs

Image Credit: Centers For Disease Control and Prevention/Wikimedia

Intestinal Worms: The Basics

Parasites are like pirates . . . they will commandeer your pet like pirates take over a ship.  You cannot always see parasites but that doesn’t mean they do not exist!

Parasites have evolved to leech nutrition from their host while simultaneously trying to evade detection and death by the host. Intestinal worms are a common health concern for many species, canines included. The most common intestinal worms in dogs are: hookworms, roundworms, whipworms, and tapeworms.

Symptoms of intestinal worms:

  • Diarrhea, sometimes bloody
  • pot-bellied appearance
  • Generalized unthriftiness
  • Ravenous appetite
  • Malnutrition
  • Occasional vomiting
  • Scooting rear on the ground
  • Coughing

Severe infestations can lead to anemia, intestinal blockages, emaciation and death.

 Your dog can acquire worms throughout a lifetime in a few common ways. Young puppies with worms are either born already infested with worms or get them shortly after birth. Larval worms can pass through the uterus to the fetuses during gestation, or through the mother’s milk to the nursing puppies. Adolescent or adult dogs acquire worms by ingesting eggs in fecal-contaminated environments, by eating infested rodents, or by ingesting fleas that contain the eggs. The worm eggs will hatch inside the dog, then migrate throughout the dog’s body and develop through stages, eventually developing into adults. Dogs with adult intestinal worms will shed eggs to the environment through the feces.

Adult worms live in the intestinal tract of dogs and hijack nutrients from their host. Some species of adult worms can grow very large and can occasionally be seen in the feces. Worm eggs cannot be seen with the naked eye. A microscopic exam of the feces performed by a veterinarian can help diagnose intestinal parasites, even if your dog does not display other symptoms of worms. This should be done yearly as a part of your dog’s routine checkup.  Even dogs on monthly heartworm preventatives can still acquire worms and may need additional medication to treat an infestation.

There are a variety of deworming medications available. The type of medication used is based on the type of worms being treated. No one medication works for all worm types. Prescription medication from your vet are usually more effective than over-the-counter medications and can be prescribed best based on the fecal exam results.

I highly recommend monthly heartworm prevention for all at risk dogs. Heartworm medication prevents against heartworm infestation (a different type of parasitic worm), as well as regularly rids dogs of the common intestinal worms. Even after treatment, dogs can easily be reinfested through the routes listed previously. If your dog is not on heartworm prevention, they should still be regularly dewormed every few months for preventative care.

Do not begin any new medications or heartworm preventatives in your dog without first discussing it with your regular veterinarian.

Some intestinal worms of dogs can infect humans! Discuss this topic further with both your regular veterinarian and physician.


Amanda Burow, D.V.M. (Dr. B), is a graduate of Iowa State University’s College of Veterinary Medicine. Dr. Burow’s patient list includes hunting dogs of all varieties, as well as several field trial dogs and full time sporting guide dogs. In addition to practicing general veterinary medicine, she has special interest in the areas of preventive care, emergency medicine, and dermatology. In her spare time, she enjoys being outdoors and on the lake, staying active, reading, and spending time with family and friends.

Mud River is proud to share these tips from Dr. B with our customers. Keep in mind it is best to work with your local veterinarian to determine the needs for your animals.


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