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Cat Worms

Veterinarian Reviewed on April 1, 2014 by Dr. Janice Huntingford

Cat Worms (Feline Worm Infestations)

Signs and Symptoms

Worms are internal parasites that infest pets such as cats, causing a variety of health problems. Most cats are exposed to worms at some point in their life, especially as kittens. These parasites live in a cat’s intestines, stealing nutrients away from the infected animal and sometimes causing internal damage. Moreover, when suffering from a worm infestation, a cat becomes more susceptible to other infections and illnesses. Since these parasites can compromise your pet’s health in a variety of ways, it’s important to make sure that your cat is properly treated whenever it is infected with worms. In order to ensure that this is possible, it’s helpful to be able to recognize some of the common symptoms that animals display when suffering from an infestation of internal parasites.

While some cats may show no symptoms when suffering from worms, in many cases there will be at least some typical warning signs exhibited. Since worms sap an animal of nutrients, a cat afflicted with a worm infestation often becomes malnourished and either loses weight or does not gain weight under circumstances in which weight gain would be expected. This latter warning sign is particularly relevant with regards to kittens that should gain weight and grow when fed a healthy diet, but may not when suffering from a worm infestation. Cats with this problem may also display appetite changes, sometimes with a loss of appetite and in other cases showing increased hunger.

Some types of cat worms suck a feline’s blood or cause blood loss due to damage to the intestinal walls, and this can lead to anemia. Cats with anemia tend to have pale mucous membranes and a rapid heartbeat. In addition, other symptoms of a worm infestation include a loss of energy and listlessness. Some felines also experience abdominal pain and develop a swollen belly. Coat changes can also be indicative of a parasite infestation, including dry, coarse, and dull fur or hair loss. Finally, a cat with worms may suffer from vomiting and diarrhea.

If you observe your cat displaying any of the above symptoms, it’s important to contact your veterinarian as soon as possible so that your pet can be examined and tested for worms. Prompt diagnosis and treatment will restore your cat’s health as well as its comfort and happiness.


Diagnosis of a case of cat worms is generally made on the basis of clinical signs and fecal testing. A veterinarian will conduct a physical exam of the feline patient, looking for any symptoms or warning signs. The practitioner will also take into account any unusual symptoms or behaviors that you have noticed at home. In addition, it’s likely that one or more forms of fecal testing will be performed in order to confirm the presence of worms and to identify the type of worm that is causing your cat’s problems.

There are a number of different types of fecal testing that can be used to check for internal parasites. These tests include direct smears, fecal floats, fecal cultures, and Baermann tests. All of these tests are performed on a sample of fresh feces and smears, floats, and Baermann tests are for the purpose of checking for the presence of worm eggs or the actual parasites themselves. Fecal cultures, on the other hand, are used to look for the presence of pathogenic bacteria like salmonella which can cause similar symptoms as internal parasites.

Different tests are used to identify different types of worms and their eggs. However, in many cases samples will not indicate the presence of internal parasites, even when they are present inside a feline patient. In fact, approximately seventy-five percent of pets that are infected with worms will have a negative result when tested. In the case of fecal floats, this is partly due to the fact that not all parasite eggs will rise to the top of the solution, even after it has been placed in a centrifuge. Since feline worm infections are very common and negative tests are so frequent even when worms are present in a cat, your veterinarian may prescribe a deworming treatment even when fecal testing turns up a negative result.


As mentioned previously, worms are internal parasites that infest cats and other animals, giving rise to a variety of problems. There are several different types of worms that commonly infect cats, including roundworms, hookworms, and tapeworms. These worms are classified by shape, with the first two types of parasite having a rounded shape and tapeworms having a flat shape. Rounded worms are known as nematodes while flat-shaped worms are known as cestodes. Nematodes live in a cat’s intestines while cestodes can live either in the intestines or other organs. Although all of these types of worms can affect felines, the most common type of worm to infest cats is roundworms.

Some worms, such as tapeworms, actually attach themselves to the intestinal walls. Roundworms, on the other hand, remain free and move around inside the intestines. In either case, worms attack the mucus lining of the intestines, feeding upon the cat’s blood and nutrients and thus preventing the cat from absorbing sufficient amounts of these nutrients. In some cases, these worms also cause damage to the intestinal lining. When these internal parasites are present in large numbers, they can potentially cause a dangerous blockage or obstruction. Sometimes these worms will stray beyond the intestines, either into the stomach or into the bowels. Some of the parasite eggs, or even the actual worms themselves, may be passed out of the body through the feces. This is why fecal testing is often conducted when a case of cat worms is suspected.

While roundworm infections are the most common with respect to cats, they are also typically less serious than other types of worm infections. However, these worms can still cause damage and compromise your pet’s health. Moreover, most worm infections will cause at least some level of discomfort for your cat. As a result, it’s important that all cases of worm infestations be properly treated under the supervision of a veterinary doctor.


Cats can contract worms relatively easily and in a number of different ways. Kittens are particularly susceptible to parasite infections, as worms and their eggs can be passed from a mother cat to her kittens through her milk or placenta. If worms are passed through the placenta, a kitten will become infected even before birth. An infected mother cat may also have eggs in her coat, which her kittens can pick up when they come in contact with her. Since mother to kitten transmission of worms occurs very frequently, mother cats and their young should be routinely treated for worms.

There are also many ways for adult cats to become infected with internal parasites. When an infected feline defecates, eggs from its feces can survive in soil and other external environments for a significant amount of time. Unfortunately, this increases the ease of transmission from one animal to another. A previously uninfected cat can quite easily pick up worm eggs from the environment and, thus, develop an infestation. This is why worm infestations are particularly common among cats that share a communal environment with other animals, such as cats that live in kennels, shelters, or farmyards. Unhygienic living conditions can also increase the chance of a cat developing a problem with internal parasites.

In addition, cats can also contract worms by eating the feces of other contaminated animals or by catching and eating small prey such as rodents that are carrying internal parasites. Eating insects like as fleas can also cause a cat to develop an infection of worms if the ingested insect was carrying parasite eggs or larvae in its system. As a result, there are numerous ways for a cat to contract internal parasites, and this is why worms are a common problem for felines.


Deworming medications or antihelmintics are typically used to treat cases of cat worm infestations. These medications are available in a variety of forms, including tablets, chewables, liquids, and topical ointments. There is no deworming medication available that will get rid of all types of worms. However, many medications will effectively treat several different types of internal parasites. Generally, deworming medications that are effective against nematodes will not be effective against cestodes, and vice versa.

Other treatment options for internal parasites include the use of homeopathic remedies. These natural products contain ingredients with properties that help to reduce symptoms and promote healing. Natural substances such as Oregon grape and fennel have antibiotic and anti-inflammatory properties and also stimulate the immune system while relaxing spasms. Furthermore, some natural ingredients also have an effect on the actual worms that are at the root of the problem. For instance, elecampane has a paralyzing effect on a worm’s nervous system while papaya is beneficial with respect to dissolving a worm’s protective outer layer. When a number of natural ingredients are used in combination, the resulting homeopathic remedy can have very beneficial effects on a cat suffering from an infestation of internal parasites. Before beginning any course of deworming treatment, however, a veterinarian should always be consulted.

Read also: Cat Salivary Tumor
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Our Expert

Dr. Janice Huntingford
Janice Huntingford, DVM, has been in veterinary practice for over 30 years and has founded two veterinary clinics since receiving her Doctor of Veterinary Medicine at the Ontario Veterinary College, University of Guelph. She has studied extensively in both conventional and holistic modalities. Ask Dr. Jan

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