Edit cart
Merchandise Subtotal:
Checkout
View all
Infectious Diseases and Parasites

Infectious Diseases and Parasites

By Arnold Plotnick, DVM

Like most mammals, cats are susceptible to problems caused by a variety of creatures and critters- specifically, bacteria, viruses, fungi, protozoa, fleas, ticks, mites, and worms. Some of these organisms are relatively harmless, while others can have serious health implications. Advances in veterinary diagnostics and therapeutics have made detection and treatment of these malignant microbes and pesky parasites much easier. A few, however, remain a challenge for cat owners and veterinarians.

Infectious Diseases

Infectious Diseases

Of all the infectious agents that affect cats, viruses remain one of the most common and the most frustrating. I've included Chlamydophila in this section on viruses because, although it is a bacterium, it often teams up with the respiratory viruses to compound the grief they cause to our kitties.

Herpesvirus

Herpesvirus

Feline herpes virus (FHV) is a major cause of upper respiratory disease in cats. FHV is very contagious between cats. Most cats become exposed to FHV at some time in their lives, and the majority of exposed cats become infected.

Causes and symptoms

Cats typically develop a mild upper respiratory infection-sneezing, conjunctivitis ("pink eye"), runny eyes, nasal discharge-which often resolves on its own. In some cats, the virus induces severe upper respiratory disease, and a few of these cats may develop persistent upper respiratory symptoms for years. The herpesvirus can also cause a variety of eye disorders and may cause skin disease as well. Although cats of all ages are susceptible, kittens appear to be affected more severely than adults.

Diagnosis and treatment

A presumptive diagnosis is made based on evaluation of the cat's history and clinical signs. After a cat recovers from the initial infection, the virus remains in the body as a latent infection. The dormant virus can be reactivated during times of stress, crowding, and concurrent illness, resulting in a recurrence of clinical signs. During these recurrences, infected cats shed the virus profusely in their ocular, nasal, and oral secretions, increasing the risk of infecting other cats. Although there are antiviral drugs that can be administered to cats showing symptoms of herpesvirus, there are currently no drugs that eliminate FHV from the body. A vaccine is available, and it is considered to be a core vaccine-all cats should be immunized against this virus.

Respiratory infections pass easily between cats.

Calicivirus

Calicivirus

The feline calicivirus (FCV) is an important cause of upper respiratory and oral disease in cats.

Causes and symptoms

Respiratory signs caused by calicivirus (sneezing, ocular discharge, nasal discharge) tend to be milder than those caused by the herpesvirus; however, calicivirus may cause ulcers on the tongue of cats and kittens. The virus is mainly transmitted by direct cat-to-cat contact, but indirect transmission via contamination of the environment or through contaminated objects is also possible. Acutely infected cats will shed the virus in oral, ocular, and nasal secretions for two or three weeks, although some cats become chronic carriers and will shed the virus persistently for months or even years. Cats of any age are susceptible, although kittens are most susceptible. Cats housed in groups, such as in boarding catteries, shelters, and breeding colonies, are at increased risk for contracting FCV.

A more serious form of calicivirus infection, caused by virulent systemic calicivirus (VS-FCV), has been reported in recent years. Disease caused by VS-FCV tends to be more severe and may be fatal.

Diagnosis and treatment

A presumptive diagnosis is made based on evaluation of the cat's history and clinical signs. Vaccines against FCV are available. The vaccine is commonly combined with the vaccines for the herpesvirus and the panleukopenia virus (the FVRCP vaccine). A vaccine against VS-FCV, the more virulent strain of calicivirus, was introduced to the market in 2007. All cats should be immunized against the common calicivirus. Whether a cat needs to be inoculated against VS-FCV or not is a matter to discuss with your veterinarian.

Vaccination against FPV is routine, and the vaccine provides cats with excellent protection from the disease.

Chlamydophila

Chlamydophila

Chlamydophila (formerly called Chlamydia) is a common cause of conjunctivitis (pink eye) in cats. Cats often acquire the infection through close contact with other infected cats. Although the majority of upper respiratory tract infections (URIs) are caused by the herpesvirus and calicivirus, approximately 10–30 percent of cats with URIs are also infected with Chlamydophila. Kittens between the age of two and eleven months are most likely to be infected.

Causes and symptoms

Chlamydophila is primarily an eye pathogen, causing redness, swelling, and discharge. It usually occurs in only one eye; occasionally it spreads to the other eye after a day or two. Sometimes nasal discharge and sneezing accompany it.

Diagnosis and treatment

A definitive diagnosis of Chlamydophila can be made by scraping or swabbing the conjunctiva of the affected eye(s) and sending the material to a laboratory, where the organism can be identified. Most veterinarians, however, make a presumptive diagnosis based on the clinical signs. The drug of choice for treatment is tetracycline, in the form of an eye ointment. Chlamydophila infections can be stubborn, and it may take several weeks before clinical signs completely resolve. A vaccine is available. Although the vaccine is considered to be a noncore (that is, not required for every cat) vaccine, it may be beneficial in shelters, catteries, and other multicat environments where disease caused by Chlamydophila has been confirmed.

Panleukopenia

Panleukopenia

Panleukopenia is a highly contagious viral disease caused by the feline panleukopenia virus (FPV).

Symptoms

Cats infected with the virus often show signs of lethargy, poor appetite, fever, vomiting, and severe diarrhea. The word panleukopenia means "a decrease in white blood cells," and that is what is seen on the blood work of affected cats. In young cats, the disease is often fatal. Queens, if infected during pregnancy, may give birth to kittens with a condition called cerebellar hypoplasia, a neurologic disorder that causes severe incoordination. The virus is spread mainly through contact with feces; however, it is very stable in the environment and can also be spread via contaminated food bowls, water bowls, litter boxes, and health care workers.

Diagnosis and treatment

Diagnosis is made based on clinical signs (mainly fever, vomiting, and profuse diarrhea), a low white blood cell count, and detection of the panleukopenia virus in the feces. Because the virus is of a type called a parvovirus, the rapid in-house test that is used to detect parvovirus in dogs can be used to diagnose the virus in cats. Treatment consists mainly of supportive care-hospitalization, fluid therapy, antibiotics, and nutritional support. With aggressive care, some cats survive the infection; most young kittens, however, succumb to the virus. Vaccination against FPV is a routine part of feline health care, and the immunity conferred by this core vaccine is considered to be excellent.

Vaccination against FPV is routine, and the vaccine provides cats with excellent protection from the disease.

FeLV and FIV

FeLV and FIV

The feline leukemia virus (FeLV) and the feline immunodeficiency virus (FIV) are among the most common-and most serious-infectious diseases of cats. Fortunately, the prevalence of both viruses in the cat population is low (approximately 2.3 percent for FeLV and 2.5 percent for FIV). The prevalence of FeLV infection has decreased over the past twenty years, due to testing programs, vaccination, and general awareness of prevention methods. The prevalence of FIV infection, in contrast, has not changed significantly since the virus was discovered in 1986. Cats who have outdoor access and exposure to other cats are at increased risk for infection. Male cats, particularly those that who not been neutered, are especially at risk.

Causes and symptoms

Both viruses can cause a variety of clinical signs in infected cats. FeLV and FIV suppress the immune system, making cats more susceptible to secondary infections. Cats infected with FeLV (and to a lesser extent, FIV) are at increased risk of developing lymphoma, a cancer of the lymphatic tissues. FeLV, as its name suggests, may cause cats to develop outright leukemia (cancer of the blood). FIV often causes or contributes to oral problems in cats. All cats who are sick, regardless of age and despite any previously negative test results, should be tested for the retroviruses. Previously tested cats may have become infected since the cat's initial testing. Don't wait for illness to have your cat tested, however. Because of the serious health consequences of infection, all cats should be tested for both viruses at some point. This includes all cats about to be adopted or brought into a new household and adult cats and kittens of any age.

Diagnosis and treatment

Because the prevalence of both viruses is low in the feline population, a negative test result is likely to be truly negative. Because of the significant implications of a positive test, cats who test positive for either virus should have the test repeated a few days later using a fresh blood sample to confirm the results. As noted earlier, kittens may be tested for FeLV and FIV at any age. A positive FeLV test strongly suggests that the kitten is infected with the FeLV virus; this should be confirmed by retesting a few days later. A positive FIV test in a kitten, however, should be interpreted carefully. The FIV test detects antibodies against the virus. The test can detect antibodies passed to the kitten from the mother. This can be mistaken for infection in the kitten. Kittens who test positive for FIV antibodies should be retested every sixty days up to six months of age. By six months of age, any antibodies that came from the mother are gone. If, after six months of age, the results are still positive, the kitten should be considered infected with FIV.

To date, no treatment has been shown to reverse a FeLV or FIV infection in cats. Although reports on the use of various drugs and supplements appear occasionally in the veterinary literature, large controlled studies are lacking regarding antiviral drugs or alternative therapies for FeLV or FIV. However, no cat should be euthanized based solely on the presence of a FeLV or FIV infection. Cats can live for many years after infection. Recent studies report the median survival of cats diagnosed with FeLV to be 2.4 years; for FIV-infected cats, 4.9 years. Every cat is an individual, however, and some cats can survive much longer, especially those with FIV. Cats diagnosed with FeLV and/or FIV should be confined indoors, both so that they do not infect other cats and to decrease their exposure to infectious agents in the environment. Because FeLV may be transmitted through mutual grooming, sharing of food bowls, water bowls, and litter boxes, cats with FeLV should be isolated and prevented from interacting with other housemates. In general, FIV transmission is low in households with stable social structures where housemates do not fight. No new cats should be introduced into the household, to reduce the risk of changing the social structure and inciting territorial aggression.

Vigilant veterinary care is required in cats who test positive for either virus. Raw foods should be avoided because of the risk of parasitic infections or exposure to food-borne bacteria. Infected cats should be examined at least twice yearly and at the first signs of illness. Internal and external parasite control is imperative. Infected queens should not be bred, and cats should be spayed or neutered if their condition is stable enough to permit surgery. Vaccines are available for both retroviruses. Both are considered noncore; that is, they are optional, based on the risk assessment of the individual cat. Cats living in a FeLV-negative, FIV-negative, indoor environment are at minimal risk.

FeLV vaccination

Because kittens are so susceptible to FeLV, it is currently recommended that all kittens be vaccinated for FeLV. Furthermore, the lifestyles of kittens often change after adoption, increasing their risk for FeLV exposure. Cats who go outdoors, cats who come into direct contact with other cats of unknown status (such as those going to foster homes or other group housing situations), and those living with FeLV-positive cats should also be vaccinated. Cats should be tested and confirmed negative prior to FeLV vaccination. Administering FeLV vaccines to cats already infected with the virus confers no benefit.

FIV vaccination

Outdoor cats who fight with other cats are at high risk for infection and may be candidates for vaccination. Because FIV is spread mainly through biting, cats living in households with an FIV-positive cat may be at lower risk for FIV infection if a stable social structure exists and fighting does not occur. In this situation, whether or not to vaccinate should be discussed with your veterinarian. If the decision falls in favor of vaccination, cats should test negative immediately prior to vaccination because vaccination of cats who are already infected, while not harmful, confers no benefit. Cats who are vaccinated against FIV will subsequently test positive for FIV antibodies. Fortunately, a test has been developed that can distinguish whether FIV antibodies are the result of infection or vaccination.

Although FIV and FeLV are serious diseases, cats infected with the virus can live long, happy lives.

If your cat has been diagnosed with FeLV and/or FIV, keep her indoors so she won't infect other cats.

Outdoor cats who fight with other cats are at high risk for infection with FIV and should be vaccinated.

Feline Infectious Peritonitis (FIP)

Feline Infectious Peritonitis (FIP)

Of all of the infectious diseases that cats can acquire, feline infectious peritonitis (FIP) is perhaps the most devastating. FIP is a viral disease caused by a type of virus called a coronavirus.

Causes and symptoms

Most cats are exposed to, and become infected with, the coronavirus as kittens. At worst, kittens may get mild diarrhea. Many show no clinical signs at all. The immune system makes antibodies against the virus but does not eliminate it, and the virus continues to reside in the intestinal tract, usually causing no further problems for the cat. Occasionally, however, for reasons not fully understood, the harmless intestinal coronavirus mutates, gaining the ability to leave the intestinal tract and cause problems. The immune system tries to defeat the virus, but the virus manages to evade it. This mutated intestinal coronavirus is now the evil FIP-inducing coronavirus. The FIP virus causes damage to blood vessels, allowing fluid to leak through the vessel walls. Effusions (collections of fluid) can develop in the abdominal cavity, chest cavity, and pericardium (the sac around the heart), resulting in what is referred to as the "wet" form of FIP. Some cats develop nodular accumulations of inflammatory cells called granulomas throughout many of the body's organs. This form of the disease is known as the "dry" form of FIP.

Diagnosis and treatment

Diagnosis of the disease is difficult because clinical signs are vague. Most affected cats are young (usually less than one year) and show lethargy, weight loss, poor appetite, and a fever that doesn't respond to antibiotics. A serum chemistry panel often only shows elevated protein (mainly in the form of increased globulins) unless the virus has begun to affect the kidneys or liver, in which case the liver and kidney parameters may be abnormal. The wet form is easier to diagnose because the presence of fluid in the abdomen or chest is relatively easy to detect, and fluid analysis can give additional information supporting the diagnosis. The dry form remains challenging to diagnose. There is no simple blood test for FIP. Many laboratories offer veterinarians an "FIP test," but these tests tend to only measure antibodies to coronaviruses in general. The tests cannot tell whether the antibodies are there due to the cat's being infected with the harmless intestinal version of the coronavirus or the deadly FIP version of the coronavirus. A positive test does not mean that the cat has FIP. Until a rapid reliable test is developed that allows veterinarians to make a diagnosis, biopsy of the affected organs or tissues remains the only way to definitively diagnose FIP.

FIP is progressive and fatal. Cats with FIP tend to succumb to the disease rather quickly, in a few days or weeks. The "wet" form of FIP tends to progress faster than the "dry" FIP. Treatment is generally symptomatic and supportive. Nutritional support, antibiotics, and corticosteroids may produce a temporary alleviation of clinical signs, but the disease invariably progresses. Ultimately, nearly all cats diagnosed with FIP are euthanized to alleviate suffering. Studies of investigational drugs have shown potential in the treatment of some cases of FIP. Polyprenyl immunostimulant (PPI), for example, has shown promise in the treatment of the dry form of FIP; controlled studies, however, are pending. Although a commercial FIP vaccine is available, the efficacy of the vaccine remains questionable. The American Association of Feline Practitioners and the Academy of Feline Medicine, in their regularly published guidelines for feline vaccination, currently do not recommend the FIP vaccine.

Fleas are the most common-and one of the most irritating-external parasites seen in cats.

Talk to your veterinarian about the latest flea-prevention strategies to determine which is the right one for you and your cat.

Parasites

Parasites

Like all household pets, cats have their share of parasites, both external and internal. Some are clearly visible with the naked eye. Others require a microscope for definitive identification. Although some of these parasites are mostly a nuisance, some can cause significant illness in cats. Fortunately, recent breakthroughs in parasite control have made treatment a much simpler and effective endeavor.

External Parasites

External Parasites

External parasites include fleas, ear mites, ticks, and a variety of other less common critters that can affect the skin, such as Cheyletiella, Demodex, and scabies.

Fleas

Fleas

Few creatures living on earth today have had as much impact on world history as the common flea. From the black plague during the fourteenth century to the present, fleas have been the cause of much grief. They make your cat itch, especially if the cat is allergic to flea bites, which is quite common. In fact, flea allergy dermatitis is the most prevalent small-animal skin disease.

It is important for cat owners to understand the life cycle of the flea. Once a flea jumps on a cat, it stays for its entire life. Fleas do not jump from one cat to another. Although the flea spends its entire life on the cat, the majority of the flea’s life cycle is completed while off the cat. When a female flea jumps onto a cat, it begins feeding on blood within minutes. Ingestion of blood is required for the flea to reproduce. By twenty-four hours, the flea starts to lay eggs, about forty to fifty per day. The cat then moves around the house, acting like a living salt-shaker, as flea eggs fall off and accumulate in the areas where the cat sleeps or rests. Within a week, larvae hatch from flea eggs. The larvae try to avoid light and burrow into carpets, cracks in hardwood floors, and other humid areas such as concrete floors in damp basements. Five to twelve days after that, larvae spin a cocoon in which they develop into pupae. Fleas emerge from pupae within one to three weeks. These newly hatched fleas wait for the cat to pass by, and then they hop onto the cat and the life cycle starts all over again.

The entire flea life cycle takes three to six weeks. When all of the life stages of the flea are looked at as a population, adult fleas compose only about 5 percent. Eggs make up 50 percent of the population, with larvae at 35 percent and pupae at 10 percent. If you're seeing adult fleas on your cat, you can be sure that there is a veritable flea factory nearby.Even if a cat spends her entire life indoors, she can still get fleas. Fleas are hitchhikers-they jump onto our clothing, and we bring them back home, where they hop onto our cats.

Causes and symptoms

The most common sign that a cat has fleas is scratching. Cats who are allergic to fleas will often experience additional signs such as hair loss, redness, and miliary dermatitis-small scabs throughout the hair coat. The most common sign that a cat has fleas is scratching. Cats who are allergic to fleas will often experience additional signs such as hair loss, redness, and miliary dermatitis-small scabs throughout the hair coat.

Diagnosis and treatment

Diagnosing fleas is easy if fleas are seen crawling through the hair coat. Sometimes, fleas may not be seen, but “flea dirt” (flea feces) is present. Flea dirt has the appearance of pepper shaken onto your cat. Combing this dark material out of the hair coat on to a moistened paper towel will resuspend the digested blood in the feces, leaving a red stain. This is a simple test and confirms the diagnosis. Fleas can cause health problems in cats in addition to severe skin irritation and flea allergic dermatitis. Fleas are also responsible for transmitting tapeworms to cats. Heavily parasitized cats, especially kittens, can develop anemia due to blood loss from flea bites. Fleas pass Bartonella, the organism responsible for cat-scratch disease, from one cat to another. Most cats infected with Bartonella are clinically normal; however, infection in cats can sometimes lead to uveitis (an inflammatory condition of the eye).

Traditionally, the most effective approach to flea control has been the three-step method: treatment of the yard, the home, and the cat. Excellent compounds are available that can be applied directly to the soil in moist, shady areas around the house where immature fleas are most likely to live. These compounds are reasonably priced, long-lasting, and environmentally friendly. As for the home environment, there are safe and effective compounds that can be applied to carpets and upholstered furniture in cases where the flea problem is especially severe, although in most instances, simply vacuuming and thoroughly washing your cat's bedding may be sufficient. Repeated vacuuming of carpets, furniture, and floors mechanically removes flea eggs and larvae from the environment. Steam cleaning reduces flea larvae in carpets. In recent years, many new flea control products have been marketed that are truly among the most effective and important formulations in the war against fleas. In fact, these products are so effective that, in most cases, the cat alone needs to be treated; treatment of the yard and the house is often no longer necessary. Many of these products are applied to the cat's fur once a month. Some are given orally. Talk to your veterinarian about which product is right for you and your cat because different products have different benefits. Some of these products not only kill fleas but also prevent ticks from attaching and may treat intestinal parasites and other parasites such as ear mites.

Ticks

Ticks

Ticks are less of a nuisance in cats than in dogs. Researchers speculate that the meticulous grooming habits of cats allow them to remove most ticks before they attach. Cats are also fortunate in that they are much less susceptible to, and thus rarely fall victim to, dangerous tick-borne diseases such as Lyme disease, ehrlichiosis, and Rocky Mountain spotted fever than dogs. Although most once-a-month flea products do not claim to be effective against ticks, some newer products are effective against both fleas and ticks.

The Tick Key

There is an excellent little gadget called a Tick Key that removes the complete tick easily and without fuss. It's key-shaped and can be attached to a key ring so that you always have it around It's extremely effective on cats, especially because they are not keen to sit still for long periods! Incidentally, the key works on dogs and people, too.

Ear Mites

Ear Mites

Ear mites are pesky little bugs that live in the ear canal of cats. They feed on skin debris, blood, and tissue fluids.

Causes and symptoms

The mites irritate the ceruminous (wax-producing) glands of the ear, causing the ear canal to fill with wax, blood, and mite feces. This material has a characteristic reddish brown appearance, resembling coffee grounds. Ear mites cause itching and discomfort. Ear mite infection is a very common disorder. Kittens often acquire the infection from their mother or from contact with another infected kitten. Affected cats often shake their heads and may scratch their ears so vigorously that bleeding results.

Diagnosis and treatment

Diagnosis is made by examining some of the crusty ear material under the microscope. The mites, which are fairly large, will be readily apparent. Treatment typically involves applying medication directly into the ears for several days. A relatively new topical product containing 0.01 percent ivermectin can be applied directly into the ear; only one dose is required. There are topical products, however, such as selamectin, that can be applied to the skin. The selamectin is absorbed into the skin and gets distributed throughout the body, including inside the ears, where it kills ear mites. Topical treatment is preferred because cats do not like (and will often fight) having medication introduced into their ears and because some mites can colonize the skin around the ear and neck. Medication instilled into the ear might not kill mites that have strayed out of the ear into the surrounding skin. Topical selamectin kills those stray mites. Removing as much debris and mites as possible before treatment is beneficial and makes treatment more successful, especially if medication is to be instilled into the ear.

Cats commonly contract ear mites, but fortunately these pests are not difficult to eliminate.

Cheyletiella

Cheyletiella

Cheyletiella are mites that can affect dogs, cats, rabbits, and people. They live on the surface of the skin, completing their entire life cycle on the host animal.

Causes and symptoms

The most common sign of Cheyletiella mange is itching and dandruff, although the itching is not as intense as that caused by other mites such as Demodex or Notoedres. The itching is mainly on the back, but it can also be anywhere on the trunk. Dry white scales are often present down the back. When a cat infested with Cheyletiella is examined closely, the dandruff can be seen to be moving, which explains the name "walking dandruff" that is often used to describe Cheyletiella. The movement is actually caused by the mites moving around beneath the dandruff flakes. Cats can develop small scabs all over their body, and symmetrical hair loss can be seen along the sides of the body where the cat might be overgrooming from the itchiness.

Diagnosis and treatment

Diagnosis is made by examining skin scrapings under the microscope; however, because the mites live on the surface of the skin, they may be detected using the "Scotch tape" technique, in which a piece of clear tape is applied to the scaly part of the skin and is then stained and adhered to a slide for microscopic evaluation. Treatment involves weekly use of a medicated dip for six to eight weeks. Other treatment options include medicated sprays, oral ivermectin, or topical selamectin. The house needs to be treated with sprays in a manner similar to that done for fleas. All cats in the household should be treated.

Demodex

Demodex

Demodicosis (also called demodectic mange) is a skin disorder that affects both cats and dogs. In cats, demodectic mange is caused by mange mites of the species Demodex cati, or Demodex gatoi. Demodectic mange is much more common in dogs than in cats. Although all ages and breeds of cats are susceptible, Burmese and Siamese cats are at increased risk.

Causes and symptoms

Two forms of the disease are possible: the localized form and the generalized form. The localized form is more common, with symptoms (hair loss, scaly skin, itching) usually limited to the eyelids, head, neck, and ears. The generalized form looks similar, but involves the body and legs as well. Cats with generalized demodicosis usually have some sort of underlying immunosuppressive disease, such as FeLV infection, FIV infection, or diabetes. In some cases, demodicosis develops after a cat has been on immunosuppressive drugs, such as corticosteroids.

Diagnosis and treatment

A diagnosis is achieved upon microscopic detection of Demodex in skin scrapings. Treatment requires medicated baths or dips using lime sulfur. The drug ivermectin, given orally, has been used successfully as well. All cats in the household should be treated because the mite is contagious between cats. Antibiotics are occasionally necessary if a secondary bacterial skin infection is present.

Notoedres

Notoedres

The Notoedres cati mite causes feline scabies (also known as notoedric mange), an uncommon, contagious skin disease of cats and kittens. This mite can also infest other animals, including humans. Although scabies is much more common in dogs than cat, a different species of mite is responsible for canine scabies.

Symptoms

Scabies is an extremely itchy disease, affecting mainly the face, ears, and neck. If not addressed promptly, the skin lesions spread to cover the entire body. The affected skin takes on a thick, crusty, scabby appearance. Cats will scratch the affected areas until they become red, raw, and inflamed.

Diagnosis and treatment

Diagnosis is achieved by doing skin scrapings of the crusty areas and observing live mites and eggs under the microscope. Scabies is commonly treated with a drug called ivermectin or selamectin. If a secondary bacterial skin infection has developed, antibiotics may be warranted.

This poor cat is possibly suffering from a scabies infestation.

Internal Parasites

Internal Parasites

The internal parasites of most concern in cats are those that affect the gastrointestinal tract. These include Coccidia, Giardia, hookworms, roundworms, tapeworms, and Tritrichomonas.

Outdoor kittens typically have worms. If you adopt a feral kitten, ask your veterinarian to screen her for worms.

Coccidia

Coccidia

Coccidia are parasitic protozoans (one-celled organisms) that mainly affect the small intestine. Cats acquire coccidial infections mainly by ingestion of soil contaminated with infected cat feces. Ingestion of infected rodents is another way of acquiring a coccidial infection, but this is less common. Most kittens acquire the infection from the feces of their infected mothers.

Causes and symptoms

Affected cats often show minimal clinical signs, although diarrhea, bloody or mucoid stools, and dehydration are sometimes seen. Kittens are more severely affected than adult cats. Cats kept in crowded or unsanitary conditions are at increased risk of becoming infected. Cats who are immunosuppressed are also at increased risk. The organism is very contagious from one kitten to another. Coccidian parasites of cats and dogs do not infect humans.

Diagnosis and treatment

Diagnosis is made upon identifying coccidial oocysts in a fecal sample. Treatment requires administration of anticoccidial medications. Most infected cats respond well to treatment; however, debilitated kittens may die from overwhelming infections.

Giardia

Giardia

Giardia is a protozoan parasite that affects mainly the small intestine, although it can occasionally affect the large intestine. Giardia lives as two different forms: a cyst form and a live trophozoite form. The cyst form is shed in the feces and infects other animals. Giardia is acquired by ingestion of contaminated feces or contaminated food or water. Once a cat eats a Giardia cyst, the cyst makes its way to the small intestine, where it opens up and releases a trophozoite, the active swimming form of the organism. The trophozoites attach to the inner surface of the intestine and reproduce by dividing in two. After this brief reproductive period, the trophozoite forms a wall around itself and becomes a cyst, which is passed in the feces. The cysts can survive for several months in the environment. The trophozoites damage the intestinal wall and are responsible for the resultant clinical signs.

Symptoms

Giardia mainly causes diarrhea, although occasionally it can cause vomiting, borborygmus (loud stomach growling noises), and weight loss. The diarrhea may be acute (sudden onset), intermittent, or chronic (persistent). Diarrhea caused by Giardia is often very watery and foul smelling and may contain blood and/or mucus. Many cats show no clinical signs at all. Giardia is seen more commonly in cats living in crowded or unsanitary conditions and in cats whose immune system is suppressed. People can contract Giardia infections, although whether the cat is a source of infection for people is a topic of debate. Until we know for certain, it is best to consider giardiasis to be a potentially zoonotic disease-one that can be transmitted to people. Immunocompromised people should avoid handling cats who have been diagnosed with Giardia.

Diagnosis and treatment

Diagnosis is made by detecting Giardia cysts on analysis of a fecal sample. However, diagnosis can be challenging because not every stool sample from an infected cat will have detectable cysts. Testing a fecal sample daily for three consecutive days increases the accuracy of diagnosis. Occasionally, cysts and/or live trophozoites are seen on direct microscopic examination of fecal sample. Another method of diagnosis involves testing for Giardia antigens in the feces using an in-house test that is similar to the type of test used to diagnose FeLV and FIV. This test is more accurate than microscopic fecal analysis. Either metronidazole or fenbendazole has traditionally been used to treat Giardia. A recent study, however, showed that giving both drugs in combination is the most effective method of treatment. Most cats respond very well, and their diarrhea resolves after treatment. Because cysts may persist in the environment, the potential for reinfection exists, especially in cats who go outdoors. Because Giardia infection is often seen in cats with compromised immune systems, all cats with Giardia should be tested for FeLV and FIV. Cats infected with either of these viruses may have a more difficult time eliminating the organism.

Cats get Giardia infestations from drinking contaminated water.

Hookworms

Hookworms

Hookworms are nematode parasites that, like roundworms, live in the small intestine. There are three main species of hookworm in cats: Ancylostoma tubaeforme (most common), Ancylostoma braziliense, and Uncinaria stenocephala. Cats acquire hookworms by either ingesting an infected host (rats, for example) or more commonly via ingestion of contaminated feces. Hookworms are not transmitted via nursing. Hookworm infection is not as common as roundworm infection.

Causes and symptoms

Hookworms attach to the wall of the small intestine and suck blood. Clinical signs are more severe in kittens than in adults and may include vomiting, diarrhea, and weight loss or failure to gain weight. Because they are bloodsucking parasites, hookworms can cause severe anemia, especially in kittens. Hookworms are zoonotic-that is, they can infect people. Human infection occurs when the skin comes into contact with soil or sand containing hookworm larvae. The larvae penetrate the skin and cause cutaneous larval migrans or "creeping eruption." The lesions appear as red lines under the skin and cause severe itching.

Diagnosis and treatment

Diagnosis of feline hookworm infection is made by seeing hookworm eggs upon microscopic examination of a fecal sample. There are many oral and topical dewormers available for treatment, most of which treat roundworms as well as hookworms. Dewormers from a pet store or from the pet section of a supermarket are not recommended because the main ingredient in some over-the-counter dewormers is piperazine, which is effective against roundworms but not hookworms.

Roundworms

Roundworms

Roundworms are nematode parasites that live in the small intestine. There are two main species of roundworm in cats: Toxocara cati (most common) and Toxocara leonina. Cats acquire roundworms by either ingesting infected hosts (mice, birds, insects) or more commonly by coming into contact with contaminated feces. Kittens may also acquire roundworms from ingestion of milk from an infected mother while nursing.

Cats who lose weight but have a normal appetite may have some type of digestive parasite.

Causes and symptoms

Kittens are more commonly affected, and they show more severe signs than do adult cats. This includes vomiting, a distended abdomen, weight loss or failure to gain weight, and diarrhea. Because the life cycle of Toxocara cati involves migration of worms through the lungs, coughing may also be a clinical sign of infection in kittens. Occasionally, live worms will be seen in the vomit and/or the diarrhea. Adult worms live in the small intestine and get their nourishment by absorbing nutrients from the cat's intestinal juices. Mature roundworms produce eggs that pass out into the cat's feces.

Diagnosis and treatment

Diagnosis is made by seeing roundworm eggs upon microscopic examination of a fecal sample or by seeing a live roundworm in the vomit or feces. Roundworms are long and thin and look like a strand of spaghetti. There are many oral dewormers available for treatment, as well as topical products that are applied to skin. Kittens should be routinely dewormed for roundworms even if fecal examination is negative because eggs may escape detection on a fecal analysis. A second treatment two to three weeks following the initial deworming is necessary to make certain that all worms were killed. Although treatment is usually successful, roundworm eggs may persist in the environment for years and can lead to reinfection, especially in outdoor cats. Roundworms are zoonotic-that is, they are a human health hazard. Their larvae may cause a condition in people called visceral larval migrans, whereby roundworm larvae migrate throughout the body. The condition occurs most often in young children who play in soil infested with roundworm eggs. Most cases are caused by the canine roundworm, although Toxocara cati has been implicated in some cases.

Tapeworms

Tapeworms

Tapeworms are long, flat worms that live in the small intestine, absorbing nutrients through their skin. Adult worms can grow up to 20 inches (51 cm) in length. The worms consist of a head and neck followed by many segments. New segments are formed and added to the neck region of the worm, while segments at the tail end of the tapeworm break off as they mature. These segments contain tapeworm eggs.

Causes and symptoms

Tapeworms rarely cause any clinical signs in the cat. Very heavy infestations may cause deprivation of nutrients, causing the cat to lose weight, although this is uncommon. Cats acquire tapeworms from ingesting an infected flea.

Diagnosis and treatment

A diagnosis of tapeworm infection is usually made by finding individual segments on the rear end of the cat, in the cat's feces, or in areas where the cat rests or sleeps. The worm segments are small and white, resembling a grain of rice. The worm segments may dry out when exposed to the air for a while, taking on the appearance of a sesame seed. Occasionally (and shockingly, for most cat owners), a live segment can be observed wriggling directly out of the cat's anus or on the nearby fur. When the segments crawl out of the anus, they may cause itching, and the cat may scoot its rear end on the floor or carpet. A diagnosis of tapeworms in the cat is proof that the cat has had contact with fleas. It is very uncommon for the feline tapeworm to infect people; however, there are rare reports of tapeworm infections in children. Treatment of tapeworms in cats is achieved using a dewormer prescribed by your veterinarian. Over-the-counter dewormers from pet stores or supermarkets are not recommended because they most likely do not contain the proper medication required to treat tapeworms.

Magnified image of the head of a tapeworm.

Tritrichomonas

Tritrichomonas

Tritrichomonas (try-trick-a-moan-us) is a protozoan that mainly affects the large intestine of cats. Cats become infected via ingestion of contaminated feces.

Causes and symptoms

Tritrichomonas causes intractable, foul-smelling, watery diarrhea, often with blood or mucus. Excessive gas, increased frequency of defecation, and straining to defecate is common. Cats of any age can be affected, although infection is most common in kittens and young cats. Cats kept in crowded or unsanitary conditions, such as shelters and breeding catteries, are also at increased risk. Tritrichomonas is not believed to be zoonotic, so it cannot be transmitted to people. However, people coming in contact with infected cats should practice basic hygiene, such as washing with soap and water after handling the feces or litter box of infected cats. Tritrichomonas is often confused with Giardia because they cause similar clinical signs.

Diagnosis and treatment

Microscopic examination of a fecal specimen is unlikely to lead to diagnosis. Instead, a diagnosis is made via culture of the stool or by a test called polymerase chain reaction (PCR). The PCR test is the most accurate, although the test is not widely available. Treatment can be frustrating. If untreated, the diarrhea often spontaneously resolves; however, that can take as long as two years. The drug ronidazole has been shown to be effective, but the drug is not approved for use in cats, so any use of the drug would be considered "off-label" usage requiring written consent from the cat owner. Although most cats tolerate the drug, some have developed neurological signs, such as twitching and seizures. These signs usually resolve when the drug is discontinued. Ronidazole can cause severe birth defects and should never be given to pregnant cats. A highly digestible diet or a diet high in fiber may cause partial resolution of the diarrhea caused by Tritrichomonas.

If your cat has an intestinal parasite, your veterinarian likely will prescribe an oral deworming medication.

From The Cat Bible, Copyright by Sandy Robins, licensed through ContentOro, Inc and used by arrangement with I-5 Press

More about cats


Save $5 on your next purchase

Remove All