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Worms in Dogs

By Colleen Williams and medically reviewed by Dr. Zac Pilossoph
published: July 11, 2017 - updated: January 18, 2023 • 7 min. read
Dog At Animal Clinic

Parasitic worms in dogs are fairly common, especially among puppies. Depending on the type of worm, your dog may have been exposed to them in utero (and through mother’s milk), or through eating infected dirt, feces, or small mammals, as well as mosquito or flea bites. If left untreated, a worm infestation can have severe consequences for a pet’s health, especially puppies and senior dogs. Learn to recognize the signs of worms in dogs and know when to visit your vet.

Symptoms of Worms in Dogs

The goal of intestinal worms is survival, which requires food and the safety to reproduce. Many types of worms live in the digestive system, where they release their eggs to hatch in the animal’s feces. While there, these parasites feed off the dog’s blood or the partially digested contents of the intestines. However, many pets show no outward signs of worms during this period– especially in the early stages of infection – so if your puppy has a penchant for eating things (and most puppies do!), be sure to regularly inspect their droppings, even if they are acting and looking normal.

There is a point though when a worm infestation can become more advanced than asymptomatic. The number one most common sign is acute to chronic diarrhea. Other common clinical signs of worms in dogs include general weakness and fatigue due to the parasitic worm causing blood loss or lack of nutrition. Weight loss is another common symptom, often accompanied by a pot-bellied appearance as the worms reproduce in the dog’s intestines. Worms in dogs can cause nutritional deficiencies, indicated by a dull coat, fur loss or skin rashes. As an infection progresses, a dog may vomit or have diarrhea; often worms or their larvae may be seen in the stool, sometimes the only indicator a parasite is present.

Yuck! Finding Worms in Dog Feces

As we mentioned, sometimes dogs with worms are asymptomatic and show no outward signs of infection. Therefore, worms (both dead or alive) found in dog droppings is usually how a pet parent discovers something is wrong; if other physical signs of worms are present, the infection is progressing and requires immediate treatment.

If you do find something noticeable in your dog’s stool, take a sample to the vet for it to be analyzed. Be sure to select “fresh” samples and place it in a sturdy, airtight container. Always wear gloves when potentially handling parasites, as some can infect humans as well.


Possible Types of Worms in Dogs

There are several types of worms that can live inside your dog, causing an array of issues:

  1. Heartworms are some of the most serious for pets and are transmitted via a single mosquito bite. Larvae enter the dog’s bloodstream can set up in various organs, most commonly the heart and lungs, where reproduction begins. Heartworm infection signs can include coughing, fatigue and shortness of breath, and even fainting/collapsing episodes. Although up to 250 worms have been found in a single dog; an individual worm can grow to 16 inches long and be enough to cause serious cardiorespiratory disease. The good news is that heartworms in dogs are easily preventable with vet-prescribed preventatives – ask your veterinarian about the correct usage of prevention meds for your pet.
  2. Hookworms can be picked up from the soil, where their larvae grow normally. After ingestion, they infect the digestive system, feeding on blood. General weakness, pale gums, or bloody diarrhea are all possible signs of these worms in dogs, although it takes a pretty heavy infection to start seeing clinical signs. Following your puppy’s regular deworming schedule is essential, as hookworms in newborn dogs are very common but also easily addressable.
  3. Roundworms are the most common parasite in dogs, according to the Companion Animal Parasite Council (CAPC), and most dogs will be infected at one point in their lives. The many ways roundworms can spread accounts for their prevalence; transmission can occur to puppies through their mother’s milk or if larvae are consumed in soil or another infected animal, like a mouse. Adult animals almost never show signs of infection, although a pot belly and dull coat may be noted in puppies with advanced cases. Stop dogs from eating any wild animals and remove feces from the backyard to prevent roundworms in dogs.
  4. Tapeworms are some of the most notorious intestinal parasites, famed for their length – up to 8 inches – and wriggly, segmented appearance. There are many different species of tapeworms who thrive in different types of mammals, including squirrels, rabbits and deer. Interestingly though, the most common mode of tapeworm transmission to a domesticated pet is via the ingestion of fleas and flea dirt. The good news is that tapeworms in dogs rarely cause actual signs. However, some possible indications, such as pets “scooting” their butts along the floor to relieve itching, may be a consequence of infection, despite this also being a common sign of several other non-related conditions. Small white segments of the worm may be visible in feces or near the dog’s anus. Your veterinarian will test a fecal sample to diagnose tapeworms, and medications to treat tapeworms generally do not have adverse side effects.
  5. Whipworms in dogs often live in the cecum, part of the digestive system where the large and small intestines meet. An infection occurs after a dog eats soil, feces or other materials containing whipworm eggs. The parasites can irritate the cecum, leading to bloody or watery diarrhea. If an infection continues to progress, so can clinical consequences, resulting in eventual weight loss and fatigue. Prevent whipworms in dogs by deworming your pets and keeping your yard clean and disposing of waste effectively.

I would put tapeworms last, below whipworms- it is a completely different class of infectious agent (flat vs round worm category) so it should be below the whips)

Can Humans Get Worms from Dogs?

It depends on the type of worm, but yes, some types of worms in dogs can be passed along to humans. Always wear gloves, shoes and long sleeves when disposing of dog poop in the backyard or collecting fecal samples.

Heartworms are rarely seen in humans, although some very isolated cases have been reported. However, the only way heartworms can be transmitted is through the bite of an infected mosquito, so pets and humans cannot pass it between each other. Even in an extremely uncommon human heartworm infection, the parasite cannot complete its life cycle and causes only minor damage to the lungs.

Tapeworms in humans are also rare, with under 1,000 cases reported yearly by the CDC.

Hookworms, roundworms and whipworms can infect humans as well as animals, preferring to wriggle their way through the skin. Walking barefoot or gardening bare-handed in infected soil are the most common causes of infection. Itchiness at the parasite’s point of entry is the most common symptom of hookworms, along with visible “tracks” where the larvae passes under the skin. Potential signs of intestinal roundworm and whipworm infection include stomach pain, vomiting, bloody diarrhea, weight loss, and general weakness.

How to Get Rid of Worms in Dogs

Deworming medications for dogs are generally the best way to prevent and/or treat an intestinal parasite infestation. Preventative medications can seem expensive in general, but when compared to the cost of treatment if an infection were to take place, the cost of regular preventatives is far more affordable than the cost to treat an active and clinically relevant infection. For example, the average cost for heartworm prevention is $5 to $15 each month, compared to $400 to $1,000 for treatment. In addition, treatment for heartworms in dogs also requires restricting a dog’s movement and activity for several months, in combination with multiple painful injections, all of which support the drive to choose prevention over risking infection.

Most of the other types of worms, which primarily reside in the intestines of a dog, are treated using an oral deworming medication. It’s important to note that, if a dog is found to have intestinal worms, making a follow-up visit with your vet is equally crucial in order to determine whether an infection is actually cured. Recurrent infections can occur, especially if preventative medications are not used. Follow puppies’ regular deworming schedule to prevent infections when your pet is most vulnerable. In addition, dogs should have a stool sample checked for parasites at least once every year, and puppies four times for the first year of life.

What to Expect After Deworming

In some cases, the pet parent may notice worms in the dog’s feces as they die or are paralyzed, depending on the medication, which can be cause for concern, but this is a normal effect of the deworming process. In rare cases, a pup being treated for worms may experience some vomiting or gastrointestinal upset, but overall, side effects are minimal. You may notice low energy or fatigue while the dog or puppy rests.

Furthermore, depending on the extent of infection, species of worm, and the animal involved, multiple deworming treatments may be needed; i.e. the initial dewormer may kill adult parasites but not larvae or eggs, meaning further treatments may be necessary. After you have administered the final dose and given it two weeks to take effect, you should take your puppy to the vet for a recheck fecal exam. If worm ova or larvae are found to still be present, one more dose of dewormer should be given.

Heartworm Treatment Side Effects

The article “What to Expect after Deworming a Dog” by Cuteness says, “A dog being treated for heartworms is at risk of suffering from a condition known as pulmonary thromboembolism. This potentially fatal condition occurs when the worms that are killed off by the anthelmintics cause a blockage of a pup’s arteries, according to the American Heartworm Society.”

Prevention is Key

Your pup is your best furry friend, so taking preventative rather than reactive measures can help lead to a healthier and more mutually enjoyable life-long relationship.

Some of the simplest an easiest measures to practice on a regular basis are as follows:

  • For good caution, take your dog to the veterinarian for routine exams, just to make sure he is worm-free.
  • Make sure to clean up your pet’s droppings in order to keep parasites out of the environment as best as possible. If your dog eliminates contaminated fecal matter outdoors and you don’t pick it up, it will get absorbed into the soil and increase the spread of parasites, which can easily get to your dog. Plus it’s impolite!
  • Be aware of common places your dog may come in contact with parasites, such as neighboring dogs, dog parks, and raw chews. Regular flea prevention can help prevent tapeworm exposure.

Additionally, a good heartworm preventative is highly important and recommended. Visit your veterinarian to ask their opinion on which brand may be best for your dog, as there are many to choose from, each of which has a different spectrum of positives and potential drawbacks.

The content is not intended to be a substitute for professional veterinarian advice, diagnosis, or treatment. Always seek the advice of your veterinarian or other qualified health provider with any questions you may have regarding a medical diagnosis, condition, or treatment options.

colleen williams
By Colleen Williams

Over the past decade, Colleen has written about health, wellness, beauty, and even pets for The New York Times, The Cut, Refinery29, xoVain, Healthy Paws Pet Insurance, and Seattle Met Magazine, as well as many beauty brands. She has a BFA in Art History from the University of New Mexico and an AAS in Fashion Design from Parsons School of Design in New York.

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Zac Pilossoph DVM vet
By Dr. Zac Pilossoph

Dr. Zac Pilossoph, a Long Island, NY born, nationally recognized veterinary medical professional, a top graduate of Tufts University Veterinary School of Medicine with postgraduate focused training in E/CC and Neurology/Neurosurgery at two of the most prestigious programs in the country, and a young multidimensional serial entrepreneur, has rapidly and single-handedly crafted a new wave of diverse global evolution and empowerment. In addition to launching several novel platforms in the extremely relevant mental wellness field, as well as establishing himself as one of the premier global veterinary cannabis educational experts, Zac is simultaneously positively advancing the clinical veterinary industry in many more ways than one. As one the only nationally licensed and recognized multidimensional relief veterinarians in the United States, with strong connections in both the private and corporate sectors, Zac has quickly established a network of colleagues and friendships that span farther than what would be thought possible. He is also relied on as a highly reputable pet product development and design consultant, with the mission of helping to uphold the highest level of quality and consistency in the diverse supplement/neutraceutical sector. Moreover, he is a trustworthy global media content editor and consultant for several different corporations, with Healthy Paws being the latest and greatest affiliation added to the list of respected partners. Lastly, he sits on the board for several different veterinary-related non-profit organizations, and regularly contributes to one or more international veterinary missionary trips on an annual basis. Ultimately, through candid education, responsible application, and constructive evolution, Zac is uniting forces, breaking down barriers, and advancing contemporary society, with no signs of stopping any time soon. With borderless impact and empowerment at the root of the mission and purpose, Zac Pilossoph is the quintessential example of just how impactful a single human can be, when the individual decision is made to finally convert fierce passion into intense action. Dr. Zac on LinkedIn ValidVet

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