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Cats Get Parasites Too

Cats Get Parasites Too


Are you a proud cat parent? Don't forget that kitties need protection against many of the same parasites as dogs. Get the facts on parasite screening and prevention to keep your cat safe with the resources below, then learn more about other parasites that affect dogs at our parasite prevention and screening campaign.

Cats and Parasites

Reviewed By Peter Kintzer DVM, DACVIM

Tapeworms are a relatively common parasite that can infect cats and has the potential to infect people as well. Read more>

Cats and Parasites

By Dr. Justine Lee

If you own a cat, this blog is a must read! Before applying any topical flea and tick medication to your cat, pay heed. One of the most commonly presenting emergencies I see is accidental poisoning of cats by their well-intentioned pet owners. Read more>

Cats and Parasites

Reviewed By Peter Kintzer DVM, DACVIM

Cheyletiellosis; no, it is not a Stephen King horror story—there is such a thing as “walking dandruff.” Walking dandruff is actually a form of mange, a skin disease caused by the Cheyletiella mite. Read more>

Cats and Parasites

See more about parasite screening and prevention by our friends at Fetch Magazine:

Reviewed By Peter Kintzer DVM, DACVIM

Our veterinarians reviewed and approved these articles to help pet parents learn as much as possible about protecting your pets:

Reviewed by:

Dr. Peter Kintzer, DVM, DACVIM


Can I catch worms from my pet?

We often worry about our pet’s health when it comes to parasites but many of us don’t realise that we might be at risk too.

Almost all pets will be affected by worms at some point, so regular worming is advisable to help combat these unwelcome passengers. Most of us worm our pets because we want to save them from any discomfort – but it’s also an essential part of reducing the risk to us as well. Some of the parasites that affect our pets, for example roundworm and hookworm, can also cause disease in you and your family. Here’s our guide to what your pet could catch and how you can reduce the risks to both you and your pet.

Dogs and cats pick up roundworm from infected soil, from hunting behaviour, or from their mother’s milk. Pregnant dogs can even pass roundworm on to their puppies via the placenta, so the majority of puppies are infected before they’re born. Adult dogs may not show signs of infection, but puppies can have symptoms that are more serious, including a pot belly, vomiting and diarrhoea, and it can even be fatal in severe cases.

Roundworm can also cause disease in humans if we unknowingly eat the microscopic eggs that infected dogs and cats shed in their poo. People can come into contact with roundworm eggs from soil (where they can survive for years), from eating food such as salad that’s not been properly washed, or from contact with pets, as eggs can stick to a cat or dog’s fur. An untreated bitch and her puppies are estimated to produce around 15 million roundworm eggs daily, so people should be particularly careful with hygiene when handling puppies and kittens. Young children are also at risk of infection playing outside in the dirt and not washing their hands well enough makes them prime targets for coming into contact with roundworm eggs.

If we do end up accidentally swallowing roundworm eggs, our immune system may step in and tackle the problem. However in some cases the larvae of this parasite migrate within our bodies where they can cause severe symptoms. If the larvae end up in the eye (a condition called ocular larva migrans), it can result in blindness. This condition, while rare, is obviously devastating and one of the reasons why it’s so important that our pets are regularly treated for roundworm.

Dogs and cats can become infected with tapeworm by swallowing infected fleas, from hunting or from scavenging (for example by eating uncooked meat).

Tapeworms are long segmented worms that live in the intestine. Small egg-filled segments break off and are passed out in your pet’s faeces – these are not alive, but remain mobile for some time, so you may see these tiny white segments that look like grains of rice crawling around the back end of your animal, or in its poo. This can lead to an itchy bottom in your pet, causing them to “scoot” along the ground in an attempt to relieve the itch. Symptoms of a tapeworm infection can include weight loss and general malaise, although often animals will not show any symptoms at all, so it’s a good idea to keep up a regular worming schedule to help combat these unwanted passengers.

Humans can get a human-specific tapeworm by eating certain meat that isn’t cooked properly. It’s also possible for tapeworms to be transmitted directly from pets to humans we can become infected with the flea tapeworm if we eat an infected flea, although it’s unusual for this to happen. Certain species of tapeworm can also cause something called “hydatid disease” in people, where cysts grow in our organs, causing disease.

Hookworm can be picked up by pets that eat hookworm larvae from the soil. Symptoms aren’t common in adult pets, but can be more serious in young dogs, and can include diarrhoea, lethargy and anaemia.

Hookworm can also affect people if we walk across a contaminated area in bare feet the larvae can burrow into our skin and cause irritation and itching.

Lungworm (Angiostrongylus vasorum) is thankfully not a threat to people, but it is particularly bad news for dogs: it can cause serious health problems, and can even be fatal. Dogs ingest lungworm larvae when they accidentally or deliberately eat snails and slugs (or even their slime) or frogs. Once ingested, the larvae make their way to the heart, where they grow into adult worms and produce eggs. These eggs travel to the lungs and hatch into larvae that the dog will cough up, swallow, and then pass out in its poo – ready to infect more snails and slugs and repeat the cycle.

Lungworm is a very nasty parasite, and one that is spreading throughout the UK. You can use this online lungworm locator to discover if lungworm has been reported in your area.

Symptoms are varied, and can include coughing, abnormal bleeding, general sickness and behavioural changes such as lethargy or depression. If you think your dog is infected, it’s important to go to the vet immediately. Thankfully, there are treatments available for lungworm and, if caught in time, most dogs will make a full recovery.

The good news is that lungworm is preventable, speak to your vet about a monthly prevention plan for this parasite.

Dealing with worms
There are a range of worming products available including spot-ons and tablets. It is recommended that pets are wormed at least every 3 months, although to protect against the lungworm (Angiostrongylus vasorum) in dogs, a preventative product needs to be given monthly. Speak to your vet about a preventative product for lungworm, as not all worming products are effective against this parasite.


Symptoms of worms in cats and kittens to be aware of

The symptoms of worms in cats and kittens differ depending on the type of worm infection they have. Usually your vet will want to pinpoint which species of worm is present so they can provide the right treatment.

You can help by regularly worming your cat and looking out for some of the tell-tale signs of infection.

All cats of all ages around the world can pick up worms , but those that hunt are at particular risk. Small rodents, such as mice, shrews and voles, as well as birds, can be carriers of intestinal parasites. Once a cat eats its prey, it can become infected.

Even kittens are not immune as roundworm larvae can be passed on in their mother’s milk and they can contract tapeworm from fleas. And, just because a cat spends its life indoors, it doesn’t mean it’s safe , fleas carrying tapeworm can easily migrate on people’s clothing and other animals into the house.

Roundworms and tapeworms are by far the most common worms found in cats, but there are many types of worms found in the UK, each causing similar but distinct symptoms.

These are long and round, as their name suggests, looking a bit like spaghetti but with a pointed end. Although their eggs are passed out in your cat’s faeces, roundworm eggs are so small that they’re not visible to the naked eye and you would never know they were there.

These unpleasant invaders can cause:

  • Sickness
  • Diarrhoea
  • Weight loss , despite a normal or increased appetite
  • A dull coat
  • Lack of energy or lethargy
  • A swollen or distended belly (in severe cases and particularly in kittens)

Unlike roundworm eggs, you can easily see tapeworm segments passed in faeces with the naked eye. Tapeworms have long, ribbon-like bodies that are cream-coloured and often their egg sacs can be shed in cat’s faeces, which look like grains of rice. The worms live in your cat’s gut, feeding on their nutrients.

While mainly older cats are affected, kittens can also be affected via ingesting an infected flea. Often cats will show no symptoms at all, but common signs to look out for include:

  • Increased appetite
  • Overly cleaning or washing the area around its bottom
  • Small segments of worms or rice-looking grains in the fur around the bottom

Although not as common as tapeworms and roundworms, pet owners should be vigilant against hookworms . They feed off the blood of the cat via the small intestine , which can lead to anaemia. In extreme cases, they can be fatal, especially in kittens. If a cat has previously been exposed to hookworm, adults may have some immunity towards these parasites, so they often don’t show any symptoms.

Common signs to look out for include:

As the name suggests, these nasty critters live in cat’s lungs . Luckily, they are less common and are rarely fatal (unlike in dogs). However, they can cause breathing problems and lung damage.

The parasite is carried by slugs and snails and is usually passed on to cats when they eat another animal, like a bird or rodent, that’s eaten an infected mollusc. Naturally, cats that hunt or are in contact with slugs and snails are most at risk.

Common signs to look out for include:

  • Coughing
  • Wheezing
  • Difficulty breathing

If you spot any of these symptoms or if you’re at all concerned about your cat’s health, you should speak to your vet.

Because worms are parasites that feed on your cat’s nutrients and, in some cases their blood, cats can develop a host of health problems , such as anaemia. In severe cases of worm infestation s, they can block the intestines, causing very serious health issues. In rare cases, worms can be fatal, especially for kittens.

Worms are everywhere and no matter if your cat stays inside all day or is newly born, they are at risk. The only way to be sure your cat is fully protected is to regularly worm them, preventing worms from causing health problems.

There is a huge range of worming products available to treat infected cat s and help prevent an infestation. These are targeted towards different types of worms and for different types of application, oral products such as worm tablets , pastes, powders, or syrups, and spot-on drops that are placed on the neck near the base of the skull.

Some products cover against both roundworm and tapeworm, while others will only treat one specific type of worm.

You should always follow the advice from your vet about how and how often to worm your cat.

Some fleas carry worms , so anywhere they go, the risk of parasites goes too. Cats should be treated for fleas every month, so worming at roughly the same time helps reduce the likelihood of tapeworm eggs being ingested by your cat via an infected flea.

Regularly worming your cat is by far the best way to avoid an infection, but you can also help reduce the risk by:

  • Regularly disinfecting litter trays
  • Washing your cat’s bedding as often as possible

You should also ensure children wash their hands thoroughly if they’ve been in a garden cats have access to. This is because in rare cases roundworms can infect humans , which can lead to blindness, particularly in children.

Remember, getting your cat regularly wormed every three months or more is the best protection against these parasites. If you have any concerns, you should always speak to your vet.


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Gastrointestinal (GI) parasitism is a common problem in cats, with prevalence rates as high as 45% in some populations. These parasites can be wormlike or one-celled protozoan organisms. They usually cause fairly nonspecific symptoms, such as a dull coat, coughing, vomiting, diarrhea, mucousy or bloody feces, loss of appetite, pale mucous membranes, or a potbellied appearance. The vomiting, diarrhea, anemia, and dehydration caused by intestinal parasites can weaken a cat, making it more susceptible to viral and bacterial infections and other diseases. Importantly, some GI parasites of cats have the potential to infect humans.

Roundworms (Toxascaris leonina and Toxocara cati) are the most common intestinal parasite of cats, affecting 25% to 75% of cats, with higher rates in kittens. Adult roundworms are three to five inches long, cream-colored, and live in the cat’s intestine, where they don’t attach to the intestinal walls and survive by eating food ingested by the host. Adult female worms produce fertile eggs that are passed in the infected cat’s feces. The eggs require several days to several weeks to develop into the infective larval stage.

Cats become infected with Toxocara cati by ingesting eggs or rodents (transport hosts) that have larvae in their tissues. Kittens can ingest larvae that pass through an infected queen’s milk, sometimes becoming infected soon after birth. Cats become infected with Toxascaris leonina by ingesting infective eggs in the environment or larvae in the tissues of rodents. This parasite cannot pass across the placenta or the queen’s milk, so cats less than two months of age rarely harbor Toxascaris leonina.

Roundworm infections are usually relatively benign, but affected kittens may show vomiting, diarrhea, constipation, or loss of appetite. If left untreated, roundworm infections may cause potentially life-threatening anemia (low red blood cell count) and, in extreme cases, stomach rupture, so infection should be taken seriously and treated aggressively. Infection is confirmed by the presence of parasite eggs during microscopic examination of the stool. Several medications treat roundworm infections effectively in cats, but owners can minimize the likelihood of infection by prohibiting hunting and reducing exposure to the feces of infected cats. Treating queens prior to breeding reduces the likelihood that the parasite will infect kittens. It is important to note that reinfection after successful treatment is relatively common.

Toxocara can infect people. When Toxocara larvae migrate through the tissues of people, they can cause damage to various organs and the eyes, called visceral larval migrans and ocular larval migrans, respectively. Although these diseases are rare, they can be quite serious, especially in young children. They can be easily avoided by preventing ingestion of Toxocara eggs from contaminated soil or hands.

Hookworms (Ancylostoma and Uncinaria) are slender, thread-like worms, less than a half-inch long, that live attached to the lining of the wall of the intestine, where they feed on the blood of the host. Because of their small size, they usually are not visible in the feces of infected cats. Hookworms are long-lived, capable of living as long as a cat. Less common than roundworm infections, the prevalence of feline hookworm infections varies considerably by geographic location in North America.

Adult cats usually become infected by larvae that penetrate their skin or that are ingested. Once the larvae enter the host, they migrate to the lungs and then to the intestines, where they develop into adult worms. It is uncertain whether cats can become infected by eating rodents with larvae in their tissues, or by ingesting an infected queen’s milk.

While mild cases of hookworm infection may cause diarrhea and weight loss, severe parasitism can cause anemia due to blood loss. In these cases, a cat’s feces will often appear black and tarry due to the presence of digested blood. If too much blood is lost, an affected cat may die without treatment. Fortunately, hookworms are easily diagnosed and treated. Good sanitation and daily cleaning of the litter box are keys to controlling hookworm infections.

Hookworm larvae (Ancylostoma) can penetrate human skin when people come in close contact with contaminated soil. As they migrate under the skin, these larvae can cause a skin condition called cutaneous larval migrans, characterized by itchiness, irritation, and long, linear, track-like lesions.

Tapeworms (cestodes) have long flattened bodies that resemble a tape or ribbon. Their small head is connected to a series of segments filled with eggs. The adult tapeworm lives in the small intestine with its head embedded in the mucous membrane lining of this part of the GI tract, absorbing nutrients eaten by the host. As the segments farthest from the head become fully mature, they break off and pass in the feces. These segments can be observed near the cat’s tail and rectum, or in the feces. The flat, quarter-inch-long segments resemble grains of rice that stretch and contract when fresh, or sesame seeds when dry.

Microscopic examination of fecal samples may not always reveal the presence of tapeworms because eggs only pass as a group in the segments. Although the discovery of tapeworm segments can alarm cat owners, tapeworm infections rarely cause significant disease in cats.

Cats usually become infected with tapeworms by ingesting infected fleas while grooming or by eating infected rodents. Fleas and rodents become infected by eating tapeworm eggs in the environment. Modern medications are highly successful at treating tapeworm infections, but reinfection is common. Controlling flea and rodent populations reduces the risk of tapeworm infection in cats.

Some tapeworm species that infect cats can cause disease in humans if eggs are accidentally ingested but good hygiene virtually eliminates any risk of human infection.

Whipworms are an uncommon parasite of cats in the United States. Adult whipworms reside in the large intestine and usually do not cause serious disease, although heavy infestations may cause diarrhea.

Stomach Worms Ollanulus tricuspis and Physaloptera species are worms that inhabit the feline stomach. Ollanulus infections occur sporadically in the U. S. and are more common in free-roaming cats and those housed in multiple-cat facilities. Cats become infected by ingesting the parasite-laden vomit of another cat. Chronic vomiting and loss of appetite, along with weight loss and malnutrition may be seen, although some infected cats show no signs of disease. Diagnosis of Ollanulus infection can be difficult, and relies upon detecting parasite larvae in the vomit. Effective treatment is available, and avoiding exposure to cat vomit is the most effective way to control infection.

Physaloptera infections are even more rare than Ollanulus infections. Adult female worms attached to the stomach lining pass eggs that are eaten by an intermediate host, usually a cockroach or cricket. After developing within the intermediate host, the parasite causes infection when a cat ingests the insect or a transport host, such as a mouse, that has eaten an infected insect. Cats infected with Physaloptera may experience vomiting and loss of appetite. Diagnosis requires microscopic detection of parasite eggs in the stool, or seeing the parasite in the vomit. Effective treatment exists, and infection can be prevented by limiting exposure to intermediate and transport hosts.

Neither Ollanulus nor Physaloptera cause disease in humans.

Isospora sp. (coccidia) are microscopic one-celled organisms that cause coccidiosis. Virtually all cats become infected with Isospora felis during their life, usually by eating a cyst, a thick-walled, egg-like stage that is passed in the feces and matures in the soil. Cysts can be infective within six hours of being excreted in feces. Cats may also become infected by eating flies or cockroaches that carry Isospora cysts.

Isospora infections usually cause no problems in adult cats, but can cause significant disease in kittens, where the coccidia may destroy the lining of the intestine and cause mucousy diarrhea. Infected kittens may also experience vomiting or a decreased appetite. Serious infections may develop in crowded environments, but good sanitation and hygiene will help control coccidia. Accurate diagnosis relies upon demonstration of microscopic cysts in the feces. Isospora of cats cannot cause disease in humans.

Giardia are one-celled organisms that move with the help of whip-like tails and parasitize the small intestine of cats. Giardia infection, called giardiasis, occurs in less than 5% of cats, but rates can be much higher in some environments. Cats become infected by ingesting Giardia cysts in the feces of another infected animal, usually a littermate or chronic carrier cat. Giardiasis is more common in multiple-cat households and catteries, and the infection rate is greater in cats less than one year old.

Giardia cysts are very resistant to freezing and municipal water chlorination. After ingesting cysts, it takes five to 16 days before a cat will show signs. Signs of infection may include acute or chronic diarrhea, although the majority of Giardia-infected cats show no signs. They do, however, remain a source of infection to other cats, although several exposures may be required to transmit infection.

Diagnosis of giardiasis depends upon microscopic identification of cysts in the stool or identification of DNA or Giardia proteins in the stool using advanced molecular biological or antibody-based techniques. For accurate diagnosis, several fecal samples may need to be evaluated because cysts are not shed continuously. Effective medications can treat giardiasis in cats, but resistance is common. Elimination of Giardia infections from households of cats may be difficult and depends on proper treatment and sanitation.

It is uncertain whether species of Giardia that infect cats are contagious to humans or vice versa, although recent studies suggest the possibility of cat to human transmission. Careful hygiene will eliminate the risk of accidental ingestion of cysts.

Toxoplasma (For more detailed information on this parasite, see our Toxoplasmosis article) Cats are the definitive host for the Toxoplasma gondii organism. Infection with this one-celled parasite is fairly common, but rarely causes disease in cats. Cats become infected by eating any of the three infective stages of Toxoplasma most commonly by eating tissue cysts in infected prey or in other raw meat. Toxoplasma multiplies in the small intestine and the oocysts are excreted in the feces after two to three weeks. These oocysts take approximately one to five days to become infective after being shed, highlighting the importance of daily cleaning of the litter box to control the spread of toxoplasmosis. Toxoplasmosis can be transmitted to humans, although most otherwise healthy people infected with this organism show few if any signs of disease. The exceptions to this are immunocompromised individuals and pregnant women, both of whom should be very careful to avoid exposure to infective Toxoplasma oocysts (see our article on Zoonotic Diseases).

The treatment of gastrointestinal parasites often requires medication prescribed by a veterinarian. Whenever using medications, be sure to follow the provided directions carefully. Parasite reinfections are very common, but can be prevented. Parasite control begins with good sanitation procedures. This includes daily removal of feces, washing the litter box with a disinfectant, such as diluted household bleach, on a regular basis, avoiding overcrowded conditions, avoiding diets with raw meats, and controlling intermediate hosts like fleas, ticks, and rodents. Good parasite control is the key to a healthier cat.


Humans can pick up roundworms from a variety of places, so it’s important to know where they are most prevalent and to follow up with good hygiene practices.

Here are a few places you could pick up roundworms.

Puppies and Kittens

All puppies and kittens are considered infected with roundworms. Puppies can actually be born with them, and both puppies and kittens can become infected by drinking their mother's milk.

When infected, pets can shed thousands upon thousands of microscopic roundworm eggs in their feces, which we can unknowingly ingest without realizing it. This is why it’s so important to promptly pick up and discard your pet’s feces, washing your hands thoroughly afterward.

Pet Waste

Roundworms can cause disease in humans if we unknowingly eat the microscopic eggs that infected cats and dogs shed in their feces. If stools are not picked up by owners, any parasite eggs present will disperse in grass and soil as the stool decays. Always use a bag to collect your pet’s feces, use gloves when cleaning the litterbox, and keep your garden free of dog waste.

Roundworm eggs can survive in soil for years, and people can come in contact with them by eating improperly washed food, such as salad greens or root vegetables. Young children are at risk of infection if they play outside in the dirt and don’t wash their hands afterward. Roundworm eggs in the soil can occasionally stick to your pet’s fur, especially if your dog or cat loves to dig — just one good reason to always bathe your pet after a trip to the dog park or hiking.


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