Cat parasites are not only annoying for animals and owners, but they can also permanently harm four-legged friends and transmit diseases. To avoid health problems for the cat, it is therefore essential to know the dangers of an infestation and to react quickly.

Some parasites can be detected with the naked eye, while others are more noticeable in the behavior of the house cat or through physical symptoms.

For example, constant exhaustion, food refusal, diarrhea, and irritated skin can all be signs of a parasite infestation. However, which abnormalities occur depends on the type of parasites.

What are Parasites?

The word parasite comes from the Greek and means nothing but a freeloader. And indeed, this word describes the nature of the little pests very accurately. Parasites can live in or on your cat. They feed on their host and even reproduce with its help.

Roughly, the pests are divided into two categories: Endoparasites live inside the cat, while Ectoparasites are found on its body surface.

The Six Most Common Cat Parasites: An Overview

Anyone who has a cat knows that the stray four-legged friends not infrequently harbor subtenants: cat parasites settle in the fur or in the organs of the animals and are sometimes also transmissible to humans. The following overview tells you what you should know about ticks, fleas, mites and the like.


Especially free roamers are threatened by worms because an infection can already occur by sniffing at contaminated feces. Worms can also be ingested by eating a mouse.  Roundworms are most commonly encountered in cats. It is estimated that 25 percent of all cats are infected with worms. This is noticeable in the cat through vomiting, diarrhea and weight loss, among other things. 

A worming cure can quickly provide relief. Especially for outdoor cats, many veterinarians advise regular prophylaxis because it cannot be completely ruled out that worms can be passed on to humans.

Roundworms in Cats intestinal tract

The need for regular de-worming for cats is often hotly debated among pet owners. Nevertheless, in particular, free-roaming cats are often infested with worms several times a year.

Such an infestation is usually harmless but can also – depending on the type of worm – cause serious diseases and organ damage. For this reason, regular de-worming is quite reasonable because this prevents the excessive reproduction of the parasites.


The tiny protozoa can make quite a mess of a cat’s intestines. So if a cat suffers from diarrhea, giardia may be responsible. Getting infected with them can happen very quickly through mutual grooming, sniffing, contact with other people’s feces, vomit, or even by the cat drinking from a water source with giardia.

Cats with a strong immune system are sometimes unaffected, while others are increasingly weakened and suffer from diarrhea and slimy feces. Giardia (Giardia intestinalis protozoan) is very resistant, so a single therapy is often not enough.

Giardia intestinalis protozoan
Giardia intestinalis protozoan

Giardia, similar to some types of worms, infects the small intestine of cats. The risk of infection with these parasites exists primarily when a house cat sniffs the feces of an infested cat. If an infestation is detected, there is an unconditional obligation to report it because the persistent parasites can also infect humans. However, that an animal is infected can only be determined when the intestinal inhabitants have already increased.

The classic symptoms are diarrhea, weight loss, vomiting and fever. A veterinarian can reliably detect giardiasis using a fecal sample or blood sample. The earlier an infestation is detected, the better it can be treated with tablets or pastes.


They are pretty easy to recognize on a white sheet of paper, but in a cat’s dense fur, they can easily be overlooked. Free roamers should therefore be checked briefly every day, at least during the tick season. With a bit of luck, they have not yet attached themselves.

Otherwise, only the quick grab for tick tongs helps. Under no circumstances should you wait for the removal because this increases the risk that the tick infects the cat with a disease through its saliva. But also, nothing should be rushed; otherwise, a part of the tick might remain in the skin.

large tick drinking blood on the little kitten's ear
Large tick drinking blood on the little kitten’s ear

You’re wrong if you think your free-roaming cat doesn’t need tick protection in the city. The little arachnids can also lurk in green spaces and the garden at home from the beginning of April to the end of October. In addition, they are initially only a few millimeters in size and, therefore, easy to overlook. For this reason, a coat check with the naked eye is not enough.


Unfortunately, they are tiny and can be overlooked for a long time. Symptoms show through increased scratching because flea bites itch immensely. If a flea infestation is not recognized and treated in time, the cat owner will have to face a lot.

This is because female fleas lay 20 to 30 eggs a day. These fall out of the fur, contaminating the cat’s entire environment with eggs and larvae, pupae and new fleas. Accordingly, it is not enough to eliminate the fleas on the cat but it requires very extensive, long-lasting cleaning measures in the apartment. Nevertheless, this is the best way to deal with a flea infestation.

Cat scratches itself because of fleas

Especially cats that have a lot of free-roaming tend to bring fleas home with them. The tiny bloodsuckers nest in the fur of the four-legged friends and cause constant itching with their bites. They can also transmit tapeworms.

Particularly in the case of a flea infestation, it is important not only to treat the animal itself but to clean the entire living space thoroughly. The reason: fleas multiply very quickly and can also jump over to humans in the further course. Especially blankets, carpets and furniture that have come into contact with the infested cat should be vacuumed or washed.


The most common type of mites that affect cats are ear mites. As is so often the case, they mainly affect outdoor cats. Mites transmit from one cat to another, and a dog can also be the culprit. With a magnifying glass, they can be seen as small white dots.

However, the brownish-black crusts in the auricles, for which they are responsible, stand out clearly. To be safe, look at your cat’s ears regularly, especially if he scratches them frequently or shakes his head. In case of infestation, you should take the cat to the vet, who will professionally clean the ears and prescribe a remedy against mites, which you must apply for a sufficiently long time.

Kitten with ear mites
Kitten with ear mites

Besides ticks and fleas, mites are the most common cat parasites. They are not visible to the naked eye. The tiny animals are usually “collected” from their hosts in tall grass and cause itching, sore skin areas and hair loss.

Ear mites, on the other hand, infest the ear canal of cats. If your pet suffers from such parasites, it will often shake its head, struggle with balance problems and constantly scratch its ears. If such an infestation is not treated by a veterinarian as soon as possible, the affected cat can become deaf in the worst case.


Cat lice (Trichodectidae, Felicola Subrostratusdo) not feed on blood but exclusively on skin scales and wound secretions, but nevertheless cause severe itching. In addition, these pests can transmit diseases and tapeworms.

You can combat the uninvited guests with special spot-on preparations. Away from their host, the perennial cat parasites die quickly, so spreading via combs and similar objects is unlikely. It would be best if you still cleaned your cat’s sleeping place.

Egg of cat louse (Phthiraptera: Trichodectidae, Felicola Subrostratus) on the hair of a cat
Egg of cat louse (Phthiraptera: Trichodectidae, Felicola Subrostratus) on the hair of a cat

How do I recognize parasites in cats?

Often it is not the parasites that we become aware of but the cat’s behavior. When a parasite bites, this often leads to itching. So if the cat constantly scratches a specific spot, we should examine it carefully. 

Possibly, the culprit is a tick, fleas, lice or mites. You can recognize Full-blooded ticks very well with the human eye. However, with only 3 millimeters of tiny fleas, it becomes already somewhat more difficult, and with lice and mites, it goes only with the magnifying glass or under the microscope. 

We should, therefore, always be on the lookout not only for parasites themselves but also for puncture marks and skin reactions. These can take the form of scratched-up skin, hair loss, dandruff or allergies.

It is almost impossible to detect endoparasites such as giardia or worms. This can only be done if, by chance, we find live worms or larvae in the feces. Unfortunately, most of the time, they are undetected in the cat’s body and can cause significant damage there. Externally recognizable symptoms include diarrhea and exhaustion. The veterinarian must examine the cat to find the cause in these cases.

Parasites in the cat: How dangerous are they?

For healthy cats, most parasites are more of a nuisance than dangerous. However, for several reasons, you should definitely treat a parasite infestation in your cat:

  • Especially in young or immunocompromised cats, parasites can cause severe symptoms of illness. Itching and hair loss are very unpleasant and lead to excessive scratching. Diarrhea is life-threatening for the cat in the worst case.
  • Excessive licking and scratching can sometimes cause injuries to the skin. In addition, if the wounds come into contact with bacteria or fungi, additional illnesses (secondary infections) are possible.
  • Parasites are often carriers of pathogens. Mostly they are bacteria, which can cause serious diseases.
  • Many parasite species are zoonoses. This means that humans and cats can infect each other.
  • Some parasites feed on the cat’s blood. Anemia may occur in the cat, depending on the severity of the infestation.

Be sure to take your cat to a veterinarian if you suspect a parasite infestation. After determining the type of parasite, he can initiate appropriate treatment. The problem is then usually solved quickly.


Parasites are, in most cases, no reason to panic. If you recognize the parasites quickly, you can almost always help your cat with suitable medication.

Some Parasites are simply annoying and do not lead to any major impairment. However, more harmful parasites can bring significant health consequences in the long term, and in rare cases, the parasite can even lead to transmission with a disease:

Ticks can infect cats with Lyme disease and anaplasmosis, and fleas can lead to worm infection. Since you can’t rule out anything at first with a parasite infestation, a visit to the vet is always recommended.


Marco Heitner

Hello, my Name is Marco. My family has had pets since I can remember. Today we have a large aquarium and, since recently, a four-month old Labrador. I am the owner of this website, and it is my great pleasure to provide helpful knowledge about pets. Our team is constantly working hard to publish well-researched reports here.


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