Common Worms in Dogs:  Parasites in our FurBabies

By Janice Jones     |Last Updated 04-08-2021

Discussing those Common Worms in Dogs and single celled organisms that live in the intestines and hearts of dogs does not make for polite dinner conversation. 

However, if left unchecked, these little creatures can make your dog and even you very ill and could be potentially deadly. 

The most common types of intestinal worms include

  • Roundworms
  • Hookworms
  • Whipworms
  • Tapeworms
  • Dogs can also acquire Coccidia and Giardia, which are single celled organisms.
  • Heartworms

Examples of Worms in Dogs


This is a microscopic image of a roundworm egg.This is a microscopic image of a roundworm egg.

The most common form of intestinal parasite is the roundworm.  Animals with roundworms pass the infection to others when they shed the worm’s eggs in their stool. 

Other animals will eat the infected feces, walk on it and lick their paw, or drink contaminated water.  Mothers can pass the infections onto their puppies either before birth or during nursing. 

Infected animals can have serious health problems including malnutrition and intestinal issues including diarrhea.  Infected animals pose a risk to people because the eggs can be accidentally eaten or enter through the skin. 

Children are at greatest risk especially if they play in areas with infected feces.  If untreated in people, the larval forms can eventually enter organs and other tissues resulting in damage.

The best way to prevent and treat roundworms is to begin in puppyhood.  Puppies should be wormed at 2, 4, 6, and 8 weeks of age and then placed on a heartworm preventative.  The heartworm medicine will also control many different intestinal parasites including roundworms.

During the dog's yearly visit to the veterinarian, a fecal sample can be checked for worms at the same time as the dog is tested for heartworms.


Microscopic photo of a Hookworm egg.Microscopic photo of a Hookworm egg.

Hookworms are also common in dogs and can be especially dangerous because they bite into the intestinal lining of the dog and suck blood.  If untreated, hookworm infestations can result in potentially life threatening blood loss, weakness, and malnutrition. 

Sadly, humans can also be affected when larvae penetrate the skin.  If hookworm larvae penetrate the skin they can cause "cutaneous larval migrans", a potentially serious and scarring inflammation results.  These infections often occur when people walk barefoot in contaminated areas, or gardening in areas where pets and other dogs have deposited their feces.  

The larvae produce severe itching and tunnel-like red areas as they pass through the skin. Symptoms that the dog may show include bloody diarrhea, weight loss, anemia, and progressive weakness.


Microscopic photo of a Whipworm eggMicroscopic Photo of a Whipworm Egg

Whipworms pass their eggs in the feces and other animals become infected by eating infected soil or licking areas of their bodies that have come into contact with the whipworm eggs. 

Whipworms are similar to hookworms in so far as they bury their heads into the lining of the dog’s intestine and such blood, but are not as harmful as the hookworm.  The Whipworm lives in the first section of the dog’s large intestine called the cecum and are often more difficult to detect because they shed few eggs. 

Some of the symptoms that a dog with whipworms may display include chronic weight loss, and feces that seems to have a  light ring of mucus and blood. 

You can prevent whipworms by maintaining a strict cleaning schedule.  Remove feces from your yard as soon as possible.  Don't neglect the yearly checkup for your dog and collect a stool sample to take along.  Many whipworm infections are more difficult to diagnosis and the only way to assure your dog does not have these worms is to have negative fecal test results.  

Whipworms rarely infect humans.


Adult Tapeworm Showing individual segmentsAdult Tapeworm Showing Individual Segments

This long flat worm consists of segments that can break off and pass in the dog's stool.  These long flat worms can continue to grow reaching lengths of between six and 24 inches.  They attach themselves to the intestines  where their egg packets break off and are passed in the feces.  This is where you might notice that your dog has tapeworms.

They appear like small grains of rice or seeds.   Each little segment has its own reproductive system.   You may see these small segments in the dog's feces or they may stick to the hair around the tail.  

There are several types of tapeworms that affect dogs and each one has a different way that can get passed onto the dog.  Tapeworms need an intermediary host to complete their life cycle.

For example, Dipylidium caninum is a tapeworm that needs fleas to be passed on whereas other tapeworms must use small animals such as rodents or larger animals such as deer or sheep.  

They can also get certain types of tapeworms by eating infected rodents.   They look like flattened grains of white rice.  People do not generally get dog tapeworms.

The only way to prevent dogs from getting tapeworms is to avoid coming into contact with the intermediary host (fleas or other animals with tapeworm infections)

Flea control is the best way as the most common dog tapeworms use fleas as their intermediary host.  

Most tapeworms do not produce severe symptoms in dogs as the other types of intestinal worms.  Many people believe that a dog who scoots his rear along the ground is infected with tapeworms.  This is not so.  Scooting is caused by anal gland problems.

People can get tapeworm infections, but they are rare.


Coccidia oocysts taken under magnificationCoccidia oocysts were taken under magnification.

Coccidia are single celled parasites that can only be seen under a microscope.  The dog becomes infected by eating infected soil or licking contaminated paws or fur. 

Once inside the pet, coccidia damage the lining of the intestine keeping your dog from absorbing nutrients. 

Symptoms include watery, bloody diarrhea.  Dehydration is also likely.  Medicines can be given to prevent the parasite from multiplying and allow time for your pet’s immune system to kill the parasite.

Read More about Coccidia in Dogs


A scanned electron micrograph if Giardia produced at the Centers for Disease Control and PreventionA scanned electron micrograph if Giardia

Giardia in dogs is another annoying parasite that can affect your dog’s health. They are not worms in dogs, but small protozoan, Giardia is not a worm, but a one-celled organism that is also capable of causing harm in many animals including people, although it’s not entirely clear how common the transmission is between dogs and people. 

Once apart of your environment, its hard to get rid of, but there are treatment options available. 

Read more about giardia in dogs.


All of the parasites on this page so far, live in the intestinal tract of your dog.  Heartworms, as the name implies, is different.  Heartworms live in the dog's heart and surrounding large blood vessels. 

This is a life threatening condition and expensive and difficult to treat.  The good news is that it is entirely preventable by giving the dog a once-monthly medication by mouth.

Read more about Heartworms

Risk Factors for Common Worms in Dogs

Four scenarios put dogs at risk for worms: 

  • Newborn Puppies:    Roundworm eggs can form cysts in adult dogs and that remain dormant.  When a female dog is pregnant, these dormant eggs will activate and infect the puppies.  The mother's milk can also pass roundworms to puppies.
  • Contact with infected dirt - Roundworm eggs and hookworm larvae can reside in dirt.  If you dog runs into infected dirt while on a walk, at a dog park, or out in the wild, your dog may get worms.
  • Fleas - Young tapeworms can reside in fleas.  If your dog swallows fleas while licking a paw or other part of his body, he could ingest tapeworms and be infected.
  • Hunting or eating wildlife - wild animals may carry worms, including tapeworms residing in fleas on wild animals.  If your dog hunts or eats wildlife, your dog may swallow worms

Diagnosis of Common worms in Dogs

  1. Intestinal Parasites:  A veterinarian can perform a simple fecal test and prescribe a de-wormer.  Most intestinal worms can be detected this way if you bring a fresh fecal sample to your veterinarian.  

  2. Tapeworms:  You can actually diagnose tapeworms yourself.  If you see small segments of the worm in the stool or adhering to the area around the anus.  These tiny segments resemble individual grains of rice and are about the same color as white rice.

  3. Heartworms are diagnosed through a blood test where the vet takes a small sample of blood and uses a test called SNAP test.
  4. Giardia:  Often vets will use a separate test if they suspect giardia because the tiny giardia organisms are more difficult to detect on a typical fecal exam.  You will still need to collect a fecal sample 

Treatment for Common Worms in Dogs

There are a few medications on the market today that will take care of the parasites in inhabit your dog.


To treat the coccidia organisms, veterinarians will use drugs  such as sulfadimethoxine (Albon®) and trimethoprim-sulfadiazine (Tribrissen®)

Toltrazuril, the generic form of the drug Baycox® is also used to treat Coccidia.

Heartworms, Hookworms, Roundworms

Heartgard Plus®

Tri-Heart Plus®

Iverhart Plus®

treats roundworms and hookworms as well as preventing Heartworm.  Their main ingredients are ivermectin and pyrantel pamoate.

Roundworms and Hookworms

Drugs such as Nemex-2® contain pyrantel pamoate and treat roundworms and hookworms. This is normally the drug of choice for treating puppies and can be use safely on puppies 2 weeks of age and older.

Strongid® is another drug that uses the generic Pyrantel Pamoate

Nemex-2 Wormer 2oz

This is a safe over-the-counter medication that you can purchase on Amazon.

Roundworms, Hookworms, Whipworms, Tapeworms, and Giardia

Drugs such as Panacur® and Safeguard® are used to treat roundworms, hookworms, whipworms and tapeworms.  Fenbendazole is the generic term for both Panacur and Safeguard.

There is no FDA approval drug for giardia, the diarrhea caused by giardia is often treated by metronidazole under the trade name, Flagyl®.

Panacur Canine Dewormer 1 gram

You do not need a prescription to purchase Panacur.


Fenbendazole will kill some types of tapeworms but not Dipylidium caninum, the most common dog tapeworm and the one transmitted by fleas.  The drug that will kill this type of tapeworm is praziquantel and is sold under the trade name, Droncit®.

Prevention of Common Worms in Dogs

  • Keeping fleas away from the dog will also prevent tapeworm infections. 
  • Do not let your dog roam and hunt; raw meat, carrion, or parts of dead animals that are likely carriers of parasites.
  • Keep your grass mowed and pick up feces frequently.
  • Keep up to date with monthly heartworm medication

Yikes, Can I Catch those Worms in Dogs?

If you have ever watched Animal Planet's “Monsters Inside Me,”  you might conclude that every worm possible in our dogs (or cats) are finding their way into our gut or worse.   You may also be asking, should I be wormed when my dog is wormed?  While it seems strange, this question has been posed by veterinary technicians who work closely with lab samples.

Luckily, the incidence of people getting worms or other parasites is very low.  A disease or condition that can be passed between animals and humans is given the term zoonotic.  There are a couple of worms that do have zoonotic potential, but again, it is very rare.

Roundworms, Hookworms and Tapeworms have the potential to be passed to people under the right conditions.


There are a couple of species of tapeworms that can be passed orally to people either by ingesting eggs or consuming vegetation or water contaminated with feces. A different species of tapeworms can be transmitted to people when the eat an infected flea.  Most of the time, children are more at risk because they put dirty hands or fingers into their mouth.


Another problematic worm that dogs get can be passed to people.  The disease in people, Toxocariasis can occur in two different forms, one that affects the eyes and the other that moves throughout the body. 

Ocular Larva Migrans occurs when a microscopic worm enters the eye and causes inflamation and scaring on the retina.  it often leads to blindness.

Visceral Larva Migrans occurs when the worms move through out the body's organs and cause fever, coughing, asthma or pneumonia.

Adults may get these parasites, but children are at greater risk. Children are most likely to get these worms if they play in contaminated dirt,  or eat something contaminated with dog feces.  


Hookworms are not always passed from dog to person, but rather, people get them through walking on contaminated soil or sand with bare feet.  They enter through the skin and cause incredible itching where the worm enters.  Other symptoms include diarrhea, weight loss and anemia.

Protect Yourself and Family From These Parasites

To protect yourself and your family the best preventative is good hygiene, which means:

  • Wash hands frequently
  • Keep sandboxes covered
  • Do not allow children to play in areas likely contaminated
  • Wear shoes when outdoors.
  • Treat fleas on your dog and your environment
  • If you suspect that you or a loved one has become infected, contact your health care provider.  DO NOT use veterinary worm medicines

Photographs on this page are courtesy of Creative Commons

Further Reading About Worms in Dogs

Pet Education

American Kennel Club

About Janice (author and voice behind this site)

Having lived with dogs and cats most of her life, Janice served as a veterinary technician for ten years in Maryland and twelve years as a Shih Tzu dog breeder in Ohio.

Her education includes undergraduate degrees in Psychology with a minor in biology, Early Childhood Education, and Nursing, and a master's in Mental Health Counseling.

She is a lifelong learner, a dog lover, and passionate about the welfare of animals. Her favorite breed for over 50 years has been the Shih Tzu, but she has also lived with Poodles, Maltese, Yorkshire Terriers, Beagles, English Bulldogs, Carin Terriers, and a Cocker Spaniel.

When not writing, reading, and researching dog-related topics, she likes to spend time with her eight Shih Tzu dogs, husband, and family, as well as knitting and crocheting. She is also the voice behind Miracle Shih Tzu and Smart-Knit-Crocheting

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