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Intestinal Parasites

Updated: Nov 11, 2020

What’s the deal with intestinal parasites?

Why should you check your pet for intestinal parasites? Whether you can see them or not, intestinal parasites are more common than you think and can affect your pet’s gastrointestinal health and overall wellbeing – and possibly yours too, as some intestinal parasites are zoonotic!

The term zoonotic refers to any disease or pathogen that can be transferred between animals and humans.

Intestinal parasites are organisms that live, feed, and reproduce in the gastrointestinal system of their host. Some intestinal parasites are species-specific; for example, the roundworms that affect dogs are different than the roundworms that affect cats, and cannot be transferred between the two species. Humans just happen to be lucky in that we can contract intestinal parasites from both dogs and cats.

These organisms can be microscopic, or large enough to see in your pets fur or stools (you can even see some of them move). No matter how small, intestinal parasites can wreak havoc on your pet’s stomach and cause severe diarrhea, vomiting, weight loss, and more. While most intestinal parasites are easily treated once diagnosed, regular testing is imperative to keeping your pets parasite-free.


How do you test for intestinal parasites?

Some intestinal parasites may be visible in the stools at certain stages of their life cycle, but most typically require a microscope to diagnose. We use an in-hospital diagnostic procedure called a fecal float to determine the presence of intestinal parasites. A fecal float provides quick results and only requires a small stool sample from your pet. The stool sample is mixed with a special liquid that causes eggs to float to the surface, where they can be transferred to a glass slide and examined under a microscope.

Most intestinal parasites can usually be detected using the fecal float method. The “usually” is dependent on the parasite’s stage of life at the time of testing. A fecal float tests samples for the presence of eggs, meaning that infection may not be detected if no eggs were being shed at the time the sample was taken. Multiple fecal floats are typically recommended when a float comes back positive, or if intestinal parasites are suspected in spite of a negative result.

Types of Intestinal Parasites

Here are some of the most common intestinal parasites pets encounter:


-Species affected: Dogs, Cats, and Humans

-Zoonotic potential: Yes

-Transmitted by: Consumption of contaminated dirt/soil, ingesting a contaminated host (ex. Rabbit), in utero or nursing from a contaminated mother.

Roundworms affect dogs, cats, and humans. The most common scenario in which a host becomes infected by roundworms is by ingesting dirt/soil that has been contaminated. This typically occurs through grooming or licking fur or paws.

Once consumed by the host, the egg becomes a larvae where it continues to grow and reproduce in the intestines. The eggs laid by the mature roundworms are then shed in the stools and reintroduced to the soil. It takes approximately 30 days for the eggs to develop enough to infect other hosts, so fresh feces are not a concern so long as they are picked up and disposed of immediately. Roundworm eggs cannot survive in the environment for long without a host.

An infected pet may experience symptoms such as diarrhea, bloody stools, weight loss/failure to gain weight, and/or a round, potbellied appearance. If a pregnant dog or cat is infected, the puppies and kittens will also be infected with roundworms when they are born and will require treatment. Additionally, puppies and kittens can become infected by nursing from their mother if she is infected with roundworms. Luckily, dogs and cats with roundworms can be easily treated with dewormer, follow-up testing, and picking up your pet’s stools from the yard.

The main way humans get roundworms is by ingesting contaminated dirt or soil particles. Human contamination rarely occurs as a result of humans knowingly eating dirt, but rather touching items that have become contaminated and not washing your hands after. Children are the most susceptible, as balls or toys played with in the backyard can easily become contaminated. Uncovered sandboxes make for a great makeshift litterbox for outdoor cats, so be sure to cover your child’s sandbox whenever they are not using it. As a general rule, we encourage all members of the family to thoroughly wash their hands after touching or handling animals.

Roundworms can usually be detected using the fecal float method. Additionally, roundworms can be visible in stools or in vomit when fully mature, though this typically occurs with more severe infestations. When visible, mature roundworms are long and white, kind of like spaghetti noodles. Please notify your veterinarian immediately if you observe worms of any kind of your pet’s stools or vomit.

Please notify your doctor if you or your child are experiencing any abnormal symptoms following your pet’s positive roundworm diagnosis, such as: fever, abdominal discomfort, swollen lymph nodes, inflammation and redness of the eye and/or vision changes.


-Species affected: Dogs, Cats, Birds, Insects, Rodents, Humans, and more.

-Zoonotic potential: Yes

-Transmitted by: Fecal-oral contact, direct skin contact, in utero or nursing from a contaminated mother.

Hookworms are an intestinal parasite that affect dogs, cats, and humans. The most common scenario in which a host becomes infected by hookworms is by fecal-oral contact, usually by ingesting microscopic particles, sniffing or eating feces, or coming in contact with contaminated soil or other surfaces.

Hookworm eggs hatch in the environment and develop into larvae outside of their host. Once the larvae has matured enough to enter the host, a hookworm may do so in one of several ways: penetrating the skin directly, being swallowed, or by eating an infected animal (such as rodents). Once inside of the host, hookworms reside in the intestines, where they latch on to the intestinal wall with their teeth and drink blood to feed. Hookworms reproduce in the intestines, where they shed eggs in the stools. Because the hookworms feed on blood, they cannot live for long outside of a host and will die in freezing temperatures.

In some cases, the hookworm larvae fail to reach the intestines and migrate to other areas of the body instead. One of the most common places hookworms migrate to is the lungs. Hookworm larvae can develop enough in the lungs to crawl towards the windpipe, creating irritation in the throat that usually results in coughing up and swallowing the larvae, helping the hookworm finally reach the intestine and reproduce with other hookworms.

An infected pet may experience symptoms such as diarrhea, bloody stools, anemia, weight loss/failure to gain weight, and lethargy. Pregnant mothers can also transmit hookworms to unborn or nursing babies. Luckily, dogs and cats with hookworms can be easily treated with dewormer, follow-up testing, and picking up your pet’s stools from the yard.

The main way that hookworms are transmitted to humans is by walking barefoot through contaminated areas, or by ingesting unwashed fruit or vegetables grown in contaminated soil. Walking on surfaces that have been contaminated by fecal matter can result in hookworms burrowing into the bottoms of your feet. Due to their size, you will not know at the time that hookworms have penetrated your feet, but hookworm infection is known to cause severe itching. As the hookworms mature, you may notice red lesions under the skin where the larvae are residing. Though far less common, intestinal infection of hookworms has been found to occur in humans. Luckily, once diagnosed, hookworms in humans is fairly easy to treat.

Hookworms can usually be detected using the fecal float method. You will not be able to see hookworm eggs in your pet’s feces. The eggs are only visible at a microscopic level. Please notify your veterinarian immediately if your pet has been experiencing loose, bloody stools, lethargy, and progressive weakness.

Please notify your doctor if you or your child are experiencing any abnormal symptoms following your pet’s positive hookworm diagnosis or possible exposure at parks or beaches, such as: intense itching, inflammation, red lesions under the skin (especially on feet or hands), fever, stomach cramping, blood in stool, or abdominal pain.


-Species affected: Dogs, Cats.

-Zoonotic potential: No

-Transmitted by: ingesting a flea.

Tapeworms in pets are different than the kind of tapeworm you might be thinking of. The kind of tapeworms that affect pets are not contagious to humans, and are caused by the ingestion of a flea (or an animal infested with fleas or tapeworms). Pets ingest fleas by licking or grooming themselves and swallowing, or eating a host that has fleas (like a mouse or rabbit). While it only takes one pesky flea to create a tapeworm, most pets with tapeworms are dealing with some type of active flea infestation.

Fleas ingest tapeworm eggs for food. When a pet eats and digests a flea, the tapeworm is released into the intestines, where the tapeworm egg begins its life cycle. The tapeworm resides in the intestines where it absorbs nutrient’s the host is ingesting through its skin. As it feeds and grows, the tapeworm grows a long segmented tail, getting larger as its digestive and reproductive tracts form. Eventually, segments of the tapeworm will exit the body in the stools, taking the segment containing the tapeworm eggs with it. Once back in the world, fleas will make their way to the freshly-dropped tapeworm eggs and feast, perpetuating the cycle.

An infected pet may not show any symptoms other than the presence of visible worms in the stool. Unlike roundworms and hookworms, tapeworms do not require a lot of nutrients and do not deplete their host, so symptoms such as stomach upset or lethargy are not associated with the presence of tapeworms. However, tapeworms can be indicative of a much larger issue: flea infestation. The tapeworm infestation will need to be addressed and treated in addition to the flea problem.

Tapeworms are usually diagnosed by the presence of tapeworm segments in the feces or around the anus. Tapeworm eggs are encased in the segments shed in the stool, so seeing a tapeworm egg on a fecal float is rare, and the segments are usually too heavy to float to the top to be collected for viewing. Tapeworms can be up to several inches long, but usually break off into segments. Each segment is flat and wide, like a fettucine noodle, though when dried (in stools or around the anus) the segments may appear white and look like rice or sesame seeds. The segments may move.


-Species affected: Dogs, Cats.

-Zoonotic potential: No

-Transmitted by: Fecal-oral contact.

Coccidia, unlike the other parasites we have discussed so far, are not worms. Coccidia are microscopic, single-celled organisms that are spread through fecal-oral contact (or by ingesting a host affected by coccidia). The spread of coccidia can be difficult to control in areas where a lot of pets are passing stools, such as shelters, breeding kennels, or doggie daycare as coccidia becomes highly contagious soon after entering the environment.

Once coccidia has been consumed, the coccidia starts to damage the cells that make up the tissue in the gastrointestinal tract. After several days, the damage to the intestines will result in loose, watery, and even bloody stools. The coccidia will reproduce and continue to shed in the stools, where it can re-enter the environment and affect new hosts. Nursing mothers cannot give it to their puppies or kittens, but infected mothers can expose their young if their feces are contaminated.

An infected pet may experience symptoms such as loose, watery stool, blood in stool, loss of appetite, vomiting, and dehydration. Pets with severe infestations, especially puppies, kittens, and senior pets, require immediate attention, as the results of severe diarrhea can lead to fatal dehydration.

Coccidia can usually be detected using the fecal float method. You will not be able to see coccidia in your pet’s feces. The eggs are only visible at a microscopic level. Please notify your veterinarian immediately if your pet has been experiencing severe diarrhea, blood in stools, or vomiting.

Coccidia cannot be transmitted to humans from pets, though you should still wash your hands thoroughly after handling contaminated feces.

Frequently Asked Questions about Intestinal Parasites

What are the symptoms associated with intestinal parasites?

The symptoms associated with intestinal parasites differ depending on the parasite. For example, coccidia can cause severe diarrhea and dehydration, whereas tapeworms have no physical symptoms other than the presence of worms in the stools. Some indicators that your pet may be due for a fecal float test include:

· Bloated or distended abdomen

· Loose, watery stools

· Blood in stools

· Vomiting

· Lethargy/Weakness

· Loss of Appetite

· Failure to Grow/Weight Loss

· Anemia

· Presence of worms in stools or vomit

The symptoms listed are not exclusive to intestinal parasite infection and can be indicative of a more serious issue. Please follow up with your vet immediately if your pet begins showing any of these symptoms.

I don’t see any worms in my pet’s stools. Do they still need to have their stools checked for parasites?

Some intestinal parasites are invisible to the naked eye at all stages of life, which means our pets can be infected without ever providing physical evidence. Even though they cannot be seen, these “invisible” parasites can be extremely harmful to your pet’s health and some can infect humans which is why we recommend having your pet’s stool sample checked for intestinal parasites at least once a year.

How can I distinguish intestinal parasites like tapeworms or roundworms from other bugs, like maggots?

If you have ever gone to pick up poop several days after it was dropped, you may have noticed dozens of little worms crawling all over. Feces tend to attract bugs like flies, who lay eggs in fresh feces. Once the eggs hatch, the fly larvae, also known as maggots, will feed on the feces. Coincidentally, maggots look like small white grains of rice – just like tapeworms. So how do you know which is which?

The best way to determine if your pet has intestinal parasites is to look at a fresh stool sample. There is a lot you can learn about your pet’s health by monitoring and tracking their bathroom habits! Finding worms in a fresh stool sample would indicate that your pet has intestinal parasites, as it takes maggots several days to hatch and grow into an actual worm.

How often does my pet need to be checked for intestinal parasites?

We recommend that adult dogs and cats have their stools tested for intestinal parasites at least once a year. However, if your pet tests positive for an intestinal parasite, retesting a stool sample once your pet has completed their deworming treatment is always recommended to confirm negative status. As puppies and kittens tend to yield more positive fecal floats than adult pets, we recommend testing more frequently during your pet’s first few months of life. Frequent testing also allows intestinal parasites that were not previously visible due to life cycle stage to be viewed and diagnosed.

How do I prevent my pet from contracting intestinal parasites?

If you give your pet monthly heartworm prevention, you are already doing one of the easiest and most effective methods of preventing (some) intestinal parasites! Monthly prevention such as Heartgard, Sentinel, and Revolution all contain a broad-spectrum dewormer that can treat any roundworms and hookworms in the intestines. Monthly prevention is dosed by weight, so ensure that your pet is receiving the correct dose for their weight to ensure protection against heartworms and intestinal parasites. Monthly flea/tick prevention is also recommended to control fleas and prevent tapeworms.

Another way you can prevent your pet from contracting intestinal parasites is by keeping your yard clear of feces. Regularly picking up your pet’s waste from the yard eliminates the environmental risk of intestinal parasites, and picking up waste is essential in avoiding recontamination when treating an active intestinal parasite problem.

Because pets can get intestinal parasites from eating feces or eating another host such as a mouse or rabbit, we recommend monitoring your dog closely when they are roaming free in wooded areas or dog parks.

How are intestinal parasites treated?

The treatment depends on what kind of intestinal parasites are affecting your pet. There are several different types of dewormer that target different parasites. A fecal float can determine what parasites are present in your pet’s stool and allow your veterinarian to prescribe the appropriate dewormer. In some cases, multiple rounds of dewormer may be required to effectively treat your pet’s infection. Most dewormers are administered orally, in either a tablet or liquid form, and rarely have any side effects.

In cases where a pet has tapeworms, the fleas will need to be addressed in addition to the deworming. Failure to control the flea problem will result in more tapeworms in the future. For more information on fleas and how to get rid of them, check out our blog:

How often does my pet need to be dewormed?

As part of their regular wellness exams, puppies and kittens will receive several rounds of dewormer in their first few months of life as they are the most susceptible to intestinal parasites. Apart from the monthly protection your pet receives from heartworm prevention against roundworms and hookworms, the only time your pet needs to be prescribed deworming medication is when there is evidence of intestinal parasites in the stools.

My pet was given dewormer to treat intestinal parasites, but I’m still noticing worms in the stool several days later. Is this normal?

Yes. The dewormer functions by killing parasites residing in the intestines, and your pet’s natural digestive process takes care of the rest. Although the dewormer kills the parasites quickly, it may take several bowel movements to clear out all of the now-deceased worms that were residing in the intestines. Depending on how severe the infection was, you may notice worms in the stool for up to a week after the dewormer was administered.

My pet tested negative for intestinal parasites, but should they be dewormed anyway to be safe?

No. Dewormer does not function as a preventative for future intestinal parasite infections and only treats any active intestinal parasite problem. We recommend starting your pet on heartworm prevention to control future exposure to roundworms and hookworms if they are not already receiving monthly prevention.

My pet tested positive for intestinal parasites. How do I prevent my family from getting them, too?

The best way to protect you and your family from zoonotic intestinal parasites is by practicing good hand hygiene after handling your pet and their waste. This includes washing your hands after picking up the yard, cleaning out the litter box, or touching your pet. Pregnant women should not clean litterboxes and should avoid handling animal feces while pregnant.

Additionally, keeping your yard clear of pet waste will reduce the risk of contamination. It is recommended that stools be picked up immediately while the pet is undergoing deworming treatment. You can also avoid the risk of contamination by thoroughly cleaning any surface or bedding that has been soiled indoors, and bathe your pet when they are visibly dirty or have feces on their fur.

We recommend following up with your physician if anyone in your home starts experiencing any abnormal symptoms.

If one pet tests positive, should I assume that other pets in the home are also positive?

Not necessarily. Since most intestinal parasites are transmitted through fecal-oral contact, each pet would have to ingest the particles in some way to become affected. Forms of ingestion may include sniffing stools, grooming or licking fur, eating/drinking from bowls contaminated with fecal particles, licking contaminated surfaces, or eating feces. Animals that spend a lot of time in confined spaces together are more likely to transmit intestinal parasites (this is why parasites are so common amongst puppies and kittens).

If one pet tests positive, speak to your veterinarian to determine if fecal float testing is recommended for the other pets in your household.

Can pets who have tested positive for intestinal parasites go on walks during deworming treatment?

Yes, you can still take your pet on walks while they undergo deworming treatment. Remember to bring bags so you can pick up your pet’s stools and avoid infecting other pets. We recommend avoiding places like dog parks or doggie daycare until your pet has completed treatment to prevent other dogs sniffing or coming into contact with your dog’s feces.

Can my pet get intestinal parasites from eating rabbit poop?

It is unlikely. While rabbits can get intestinal parasites, remember that many of the parasites animals deal with are species-specific and do not affect dogs and cats. For example, the type of coccidia that affects rabbits will not affect a dog that ingests contaminated rabbit feces. However, pets should be discouraged from eating rabbit poop because unexpected changes in diet can lead to upset stomach.

Can I purchase dewormer over-the-counter without a prescription?

Yes, but this is not recommended. There are a few types of oral dewormers labeled for use in farm animals that can be purchased in-stores. While these dewormers are similar to the dewormers you might be prescribed by your vet, you should always consult your vet before giving any over-the-counter medication.

We do not recommend giving any medication to your pets that has not been prescribed or recommended by your vet. Not all medications labeled for use in some animals are safe for all species and determining the safest dose for your pet at home can be tricky – and possibly fatal if miscalculated. To be safe, talk to your vet about any medication or product you are considering trying with your pet before administering the product.

Additionally, different types of dewormers target different intestinal parasites, so it is important to know what kind of intestinal parasites your pet is dealing with before starting treatment. As it is impossible to detect some types of intestinal parasites without a microscope, diagnostic testing such as performing a fecal float is usually required for successful treatment.

Are there any natural home remedies I can use to deworm my pet if they have intestinal parasites?

The safest and most effective way of eradicating intestinal parasites is through veterinarian-prescribed deworming medication that specifically targets and kills the parasite. Unfortunately, there are no natural or home remedies that have been proven to successfully treat intestinal parasites in pets. We strongly advise against any form of intestinal parasite treatment that is not overseen by your vet.

Popular internet searches for home deworming methods for pets wrongly suggest feeding foods like garlic or pumpkin seeds to resolve the intestinal parasites. Garlic is extremely toxic and can lead to organ failure in dogs and cats, and there is no evidence that certain foods or ingredients can kill intestinal parasites. We recommend skipping the internet search and contacting your veterinarian for treatment recommendations.

If you have noticed any changes in your pet’s bowel movements or stools, please call us at 972-347-6100 to discuss.



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