About Intestinal Parasites and Worms in Dogs

View video transcript

[Dr. Jeff Werber:
Dogs have a nose for adventure, but sometimes, they can get into trouble without even knowing it. Intestinal parasites, or “worms,” as most people call them, are a common and widespread danger to your pet. It’s important to distinguish intestinal worms from heartworms. They are two completely different things, and dogs get them in very different ways. Here, we’re talking about intestinal worms that infect your dog’s digestive system.

Dogs get intestinal parasites in one of four ways: by ingesting worm eggs or worm larvae in feces or infected soil; by ingesting raw meat or remains of an animal that has been infected; by becoming infected by worm larvae puncturing the skin, as is the case with hookworm infection; or directly from their mothers, either while she is still pregnant or through her milk.

The larvae migrate throughout your dog’s body before attaching themselves to the intestinal tract, where they grow into adult worms that feed off your pet and cause significant health issues.

Dogs with intestinal parasites can suffer from diarrhea, dehydration, blood disorders, inflammation of the large intestine and coughing. Worms can cause weight loss in adult dogs and failure to thrive in puppies. In severe cases, intestinal parasites can be fatal. Some of the most common intestinal parasites are roundworms, hookworms and whipworms. Let’s take a closer look at the lifecycles of these three dangerous parasites.

Roundworm eggs can be found in dog feces, infected animals and animal remains. The eggs can remain in the yard even after the initial source has disappeared. Dogs ingest the infected eggs. After hatching, the immature worms usually pass through the dog’s liver and lungs and settle into the dog’s intestines, where they mature into adults. From there, adult roundworms lay more eggs, which are passed through the dog’s feces back into the environment.

Dogs can get hookworms through animal feces, small infected animals and insects, or when hookworm larvae penetrate the dog’s skin. When a dog becomes infected, the larvae move to the small intestine, where they mature into adults. Sometimes, they move into the lungs or skeletal muscles, where they remain dormant until migrating to the intestinal tract. Hookworms can live up to two years, feeding off your dog’s blood and the walls of his intestines.

Finally, dogs get whipworms by ingesting the worm larvae present in the environment. Whipworm eggs can remain viable in the soil for many years. Once inside the intestines, the worms take approximately three months to mature into adults. Once this occurs, adult whipworms live in the dog’s large intestines and only shed eggs intermittently. However, female whipworms can produce up to 2,000 eggs each day.

So how do you know if your dog has worms? Your veterinarian will test your dog’s stool for worm eggs at his yearly checkup. Other signs to watch for include coughing, vomiting, diarrhea (especially if there are signs of blood), worms in his stool, lethargy, an appearance of a “pot belly,” weight loss, dull coat or scooting his bottom across the floor. Only veterinary tests for intestinal parasites can provide an accurate diagnosis, so be sure to visit your veterinarian if you suspect your dog may have contracted worms.

To reduce the risk of your dog or family coming in contact with worm eggs and larvae, pick up feces immediately when walking your dog and clean your yard often. And follow the Companion Animal Parasite Council’s guidelines for fecal testing. Worms are a continuous threat, so ask your veterinarian about effective treatments that can help protect your dog from intestinal parasites all year round. Just one dose every month can make a big difference in the health and well-being of your pet.

Ask about Trifexis, the combination product that kills fleas and prevents infestations, prevents heartworm disease, and treats and controls hookworm, roundworm and whipworm infections. See the full product label for complete safety information.

Serious adverse reactions have been reported following concomitant extra-label use of ivermectin with spinosad alone, one of the components of Trifexis. Treatment with fewer than three monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention. Prior to administration of Trifexis, dogs should be tested for existing heartworm infection. Use with caution in dogs with pre-existing epilepsy.

The most common adverse reactions reported are vomiting, depression, itching and decreased appetite. To ensure heartworm prevention, observe your dog for one hour after administration. If vomiting occurs within an hour of administration, redose.]

Warding Off intestinal parasites in dogs

Intestinal parasites such as roundworms, hookworms and whipworms can be a danger to dogs. That’s why broad-spectrum parasite protection is important to help keep your dog healthy. Trifexis® (spinosad + milbemycin oxime) protects dogs against three types of intestinal parasites with just one chewable tablet each month.

If your dog has intestinal parasites, the parasitic infection could cause symptoms such as1,2,3:

  • Weight loss
  • Diarrhea
  • Dehydration
  • Anemia
  • Blood loss
  • Inflammation of large intestine
  • Coughing
  • Even death, if left untreated

Talk to your veterinarian about year-round, monthly parasite control to see how Trifexis can be your first line of defense against intestinal parasites in dogs.

What are intestinal parasites?

In a word, intestinal parasites are worms. Roundworms, hookworms and whipworms live in your dog’s body and grow to adulthood in the intestinal tract. Each follows its own lifecycle and can be contracted in different ways by your dog1,2,3:

  • By ingesting
    • Feces
    • Other vertebrate or invertebrate hosts (e.g. rodents, birds, cockroaches, earthworms)
    • Contaminated soil (by licking paws or toys)
  • Directly from their mother before birth or via milk

Some intestinal parasite eggs are incredibly resistant to environmental changes and can remain dormant in the soil for several years before infecting your dog or a member of your family.1,3

Roundworms in dogs1

Roundworms are extremely common parasites for pets throughout the world. Young pups tend to experience the most severe effects of disease caused by roundworm infection. These infections are particularly problematic because dogs can become infected over and over again.

Roundworm lifecycle (Toxocara canis)

Roundworm Life Cycle image

Approximately 2-4 weeks after infection, adult roundworms release eggs in the dog’s small intestine.

Eggs are passed in the feces.

Eggs develop in the environment and become infective 2-4 weeks after being passed in feces.

Infective eggs may be ingested by your pet directly from the environment.

Paratenic hosts, such as earthworms and field mice, ingest infective eggs and become carriers of larvae that arrest in somatic tissues.

Humans may accidentally consume infective roundworm eggs, which can lead to the development of a zoonotic disease affecting the eye, brain and/or other organs.

An infected vertebrate paratenic host is consumed, and larvae are released in the dog’s small intestine where they become adult worms.

Larvae are released from infective eggs, burrow through the intestinal wall, move through the dog’s liver and lungs, are coughed up, swallowed and mature within the small intestine. During this migration, some may stop development and arrest in the somatic tissues.

Puppies may become infected by larvae through the placenta during pregnancy or the milk during nursing.

Roundworm lifecycle (Toxascaris leonina)

Roundworm Life Cycle image

Approximately 8-10 weeks after infection, adult roundworms release eggs in the dog’s small intestine. 

Eggs are passed in the feces.

Eggs develop in the environment and become infective approximately 1 week after being passed in feces.

Infective eggs may be ingested by your pet directly from the environment.

Paratenic hosts, such as earthworms and field mice, ingest infective eggs and become carriers of larvae that arrest in somatic tissues.

An infected vertebrate paratenic host is consumed, and larvae are released in the dog’s small intestine where they become adult worms. 

Larvae are released from infective eggs and mature in the dog’s intestinal tract. 

Hookworms in dogs2

In dogs, hookworm (Ancylostoma caninum) infection is associated with:

  • Failure to thrive 
  • Diarrhea
  • Anemia
  • Dehydration

Hookworm lifecycle

Hookworm Life Cycle image

Inside the dog’s small intestine, adult female hookworms release eggs.

Eggs are released in feces approximately 10-21 days after infection.

Feces contaminate soil in your yard where immature worms develop from the eggs in about a week.

By walking or playing where dogs frequent, immature worms can infect humans through exposure to unprotected skin.

Contaminated soil on toys or dog’s paws may put the dog at risk of infection if ingested.

Immature worms can remain dormant in your dog’s skeletal muscle.

Skin may be penetrated by immature worms in contaminated soil.

A puppy may become infected through milk when larvae migrate to their mother’s mammary glands.

Whipworms in dogs3

Dogs can become infected with whipworms (Trichuris vulpis) by ingesting whipworm eggs from a contaminated environment. Many whipworm infections are asymptomatic but can result in:

  • Bloody diarrhea
  • Weight loss
  • Dehydration
  • Even death, in severe cases

Whipworm lifecycle

Whipworm Life Cycle image

Inside the dog’s large intestine, adult whipworms live and release eggs.

Eggs are released in feces 74-90 days after infection.

Eggs contaminate the soil in your yard, where they may persist for years.

Invisible to the naked eye, larvae develop in eggs and become infective in 9-21 days.

Contaminated soil on toys or dog’s paws may put the dog at risk of infection if embryonated eggs are ingested.

After ingestion, larvae hatch from eggs and are released into the gastrointestinal (GI) tract, penetrate the intestinal wall, develop for 2-10 days then move to the cecum where they mature into adults.

Intestinal parasites can be dangerous for your dog

View video transcript

[Dr. Jeff Werber:
After you start your dog on intestinal parasite protection, it is possible for parasite eggs to show up in your dog’s fecal test. Rest assured, this can happen even when the product is eliminating parasites effectively.

There are three main reasons why your veterinarian may see eggs in your dog’s stool. Worms living in your dog’s muscles or internal organs are able to hide from the effects of monthly intestinal parasite preventatives. These worms can emerge from hiding, travel to the intestines and start producing eggs between doses of medication. Additionally, an intestinal parasite preventative deworms the dog only at the time of dosing. Your dog could become infected with new parasites that mature and start to produce eggs between monthly doses. Finally, your dog could be spitting out his monthly dose or be on an improper dose for his size, especially if he is a growing puppy.

Left untreated, intestinal parasites can cause serious health issues for your dog. They can also be spread between pets and to people, so be sure to treat all the pets in your home with an appropriate monthly parasite product. Nothing can completely prevent dogs from getting intestinal parasites, but veterinarian-recommended products are effective at treating and controlling them. For more advice, plus tips on protecting your other pets from intestinal parasites, talk to your veterinarian.

Ask about Trifexis, the combination product that kills fleas and prevents infestations, prevents heartworm disease, and treats and controls hookworm, roundworm and whipworm infections. See the full product label for complete safety information.

Serious adverse reactions have been reported following concomitant extra-label use of ivermectin with spinosad alone, one of the components of Trifexis. Treatment with fewer than three monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention. Prior to administration of Trifexis, dogs should be tested for existing heartworm infection. Use with caution in dogs with pre-existing epilepsy.

The most common adverse reactions reported are vomiting, depression, itching and decreased appetite. To ensure heartworm prevention, observe your dog for one hour after administration. If vomiting occurs within an hour of administration, redose.]

It’s vital to protect your dogs and cats from intestinal parasite infections because they can be passed from one pet to another. That’s why the Companion Animal Parasite Council recommends administering year-round protection to control internal and external parasites.4 Trifexis protects dogs against hookworm, roundworm and whipworm infections—three dangerous parasites—as well as fleas and heartworm disease.

Learn more about Trifexis

 

Parasites can also raise human health concerns5

Intestinal parasites can also be a danger to you. Some zoonotic diseases can be transmitted from animals to humans. Anyone who comes in contact with fecal-contaminated soil is at risk. Individuals with compromised immune systems may suffer severely from these opportunistic infections, including infants and the elderly.