Coccidiosis (Isospora and Sarcocystis species) is an enteric infection, traditionally associated with Isospora canis (dogs) and Isospora felis (cats) as potential pathogens. Other species of Isospora may be present. Strictly host specific, i.e., no cross-transmission.
Coccidia is one of the most commonly seen parasites in cats, and is most common in young kittens and more likely to be seen where conditions of poor sanitation, stress and crowding exist. Cats acquire the parasite by ingesting any source that has been contaminated by infected cat feces or by ingestion of infected rodents or other meat sources.
Infected cats may exhibit weight loss, weakness, dehydration and diarrhea with possibly blood and/or mucus being present. Kittens, immunocompromised or otherwise weakened cats will have more severe symptoms. Older and otherwise healthy cats may exhibit no symptoms whatsoever.
Albon is the most commonly used drug for treatment of Coccidia. In severe cases of diarrhea, fluid therapy may be necessary to correct dehydration and electrolyte balance.
>>Return to Top<<
Giardia are sometimes confused with worms because they invade the gastrointestinal tract and can cause diarrhea. They are not worms; instead, they are one-celled parasites classified as protozoa. Most cats that are infected with Giardia do not have diarrhea or any other clinical signs.
When the eggs (cysts) are found in the stool of a cat without diarrhea, they are generally considered a transient, insignificant finding. However, in kittens and debilitated adult cats, they may cause severe, watery diarrhea that may be fatal.
A cat becomes infected with Giardia when it swallows the cyst stage of the parasite. Once inside the cat's intestine, the cyst goes through several stages of maturation and replication. Eventually, the cat is able to pass infective cysts in the stool. These cysts lie in the environment and can infect other cats. They may also be transmitted through drinking infected water.
Giardiasis is diagnosed by performing a microscopic examination of a stool sample. The cysts are quite small and usually require a special floatation medium for detection, so they are not normally found on routine fecal examinations. Occasionally, the parasites may be seen on a direct smear of the feces.
A blood test is also available for detection of antigens (cell proteins) of Giardia in the blood. This test is probably more accurate than the stool exam, but it requires several days to get a result from the laboratory performing the test.
The typical drug most commonly used to kill Giardia is metronidazole (Flagyl), an antibiotic-type drug. It is given for 5 - 7 days. Other drugs are also used if diarrhea and dehydration occur. If metronidazole is not effective, other drugs such as quinicrine, panacur, albendazole and furazolidone are all commonly used.
Giardia can also cause diarrhea in humans. Therefore, environmental disinfection is important. The use of chlorine bleach, one cup in a gallon (500 ml in 4 liters) of water, is effective if the surfaces and premises can be safely treated with it. Remember to use gloves for your protection and to thoroughly rinse the litter box before allowing the cat access so that it does injest any bleach or irritate its paws.
>>Return to Top<<
Cryptosporidium is still being assessed as an acute life-threatening coccidiosis (cryptosporidiosis) of neonatal kittens. Voluminous watery diarrhea is characteristic; autoinfection and continuing recycling within the lower intestinal tract results in a rapid loss of the mucosal lining.
Cryptosporidia are the smallest of all coccidia-type parasites and attacks the intestines of cats and many other warm-blooded animals. Although many cats become infected, few show clinical signs other than severe diarrhea. Most cats with actual cryptosporidial illness will be FeLV positive or otherwise weakened. Usually, the primary symptom of infection is chronic, persistent and watery diarrhea, weight loss and a poor appetite.
Diagnosis is made by fecal analysis by sugar flotation (oocysts are acid- fast positive), fecal antigen detection tests, or fluorescent antibody tests.
Humans can become infected by cats and vice versa which is the most serious aspect of this type of infection. In cats, treatment with paromomycin has resulted in the resolution of signs and the cessation of oocyst shedding.
>>Return to Top<<
J. P. Dubey, M.V.Sc., Ph.D.
Microbiologist, Zoonotic Diseases Laboratory,
Agricultural Research Service,
United States Department of Agriculture
Toxoplasma gondii infects most species of warmblooded animals, including humans. Infection in cats is of particular interest because Felidae (domestic, and wild) are the only known definitive hosts for T. gondii and thus are the main reservoirs of infection. Toxoplasma gondii infections are common in most mammals worldwide.
Cats can acquire infection by three primary ways: carnivorism, ingestion of feces, and congenital infection. Of these three, carnivorism is the most efficient means of transmission of T. gondii in the cat. Most cats become infected by eating infected tissues containing T. gondii tissue cysts.
After ingestion of tissue cysts by the cat, the cyst wall is dissolved by the digestive fluids in the stomach and small intestine. The released bradyzoites penetrate the epithelial cells of the small intestine and initiate a series (types A to E) of genetically determined asexual generations followed by the sexual cycle. After the male gamete fertilizes the female gamete, a wall is formed around the fertilized female gamete to form an oocyst.
Oocysts are unsporulated when passed in feces and are therefore uninfective. After exposure to air they sporulate and then contain two sporocysts, each with four sporozoites. Sporulation takes 1 day or more after excretion, depending on environmental conditions. The entire coccidian cycle of T. gondii can be completed within 3 days of ingestion of tissue cysts.
The life cycle of T. gondii in extraintestinal tissues is the same for all hosts, including cats, mouse, and humans. After ingestion of infected tissues or oocysts, the bratlyzoites or sporozoites penetrate intestinal cells, multiply as tachyzoites, and spread to other organs.
Tachyzoites multiply in almost any type of host cell until the cell is destroyed. The released tachyzoites repeat the cycle in new host cells and eventually encyst. Tissue cysts are formed in the brain, muscles, heart, and visceral organs and probably persist for the life of the host.'
Parasiternia during pregnancy can cause placentitis followed by spread of T. gondii to the fietus. Congenital infection can occur in cats as in other hosts. Congenital infection can be fatal in cats.
>>Return to Top<<
As their name implies, these are worms which have round bodies. On average, they are about 3 - 5 inches (7 -12 cm) long. They live in the cat's intestines and consume partially digested food. Unlike hookworms, they do not attach to the intestinal wall; rather, they literally swim in their food. Roundworms, sometimes called ascarids, pass moderate numbers of microscopic eggs which are found in the cat's stool. Like hookworm eggs, they must be found with a microscope.
The major source of roundworm infection for kittens is the mother's milk. Roundworm larvae (immature worms) may be present in the queen's mammary glands and milk throughout the period of nursing the kittens.
Both kittens and adult cats may become infected by swallowing roundworm eggs which contain infective larvae. The larvae hatch out in the cat's stomach and small intestine and migrate through the muscle, liver, and lungs. After several weeks, the larvae make their way back to the intestine to mature.
When these worms begin to reproduce, new eggs will pass in the cat's stool, and the life cycle of the parasite is completed. Obviously, roundworm eggs passed in one cat's stool may be infectious to other cats. Interestingly, a large number of other animal species have been found to harbor roundworms and represent potential sources of infection for cats. These include cockroaches, earthworms, chickens, and rodents.
Roundworms are not highly pathogenic (harmful) to adult cats, but large numbers can cause weight loss and a pot-bellied appearance to kittens and weak adults. Decreased appetite, vomiting or diarrhea will be observed on occasion. Kittens will sometimes die with serious roundworm infections.
Roundworms are diagnosed by a microscopic examination of the cat's stool. They pass a moderate number of eggs, so examination of more than one stool sample may be necessary to find them. Occasionally, the mature worms can be found in the cat's stool or vomit.
Treatment is quite simple. Several very safe and effective drugs are available to kill roundworms in the intestine. Some of these drugs temporarily anesthetize the worms so that they pass out of the cat with a normal bowel movement.
The live or dead worms are found in the stool. Because of their large size, they are easily seen. At least two or three treatments are needed; they are typically performed at 2 - 4 week intervals. None of these treatments will kill the immature forms of the worm or the migrating larvae.
Do not use "dewormers" commonly sold over the counter, often these chemicals will make the cat ill and fail to resolve the problem. Over-the counter-wormers can be very toxic and irritating to your cat and should be avoided. These medications are often very specific so a "one size fits all" approach is no longer acceptable and may actually be dangerous.
Also, if other problems secondary to a parasitism have occurred, such as dehydration, worming alone will not cure your cat.. The safest and most effective drugs can be prescribed only by your veterinarian.
The eggs are highly resistant to most commonly used disinfectants and to even harsh environmental conditions. Therefore, removal of the cat's stool is the most effective means of preventing reinfection. A 1% solution of household bleach can be used to remove the sticky outer coating of the eggs, making it easier to rinse them away.
This does not, however, kill the eggs. Remember the obvious limitations about where bleach may be safely applied. If bleach is used in the cat's litterbox, be sure to rinse it completely since bleach is toxic to cats.
The roundworms of both cats and dogs pose a health risk for humans. As many as 10,000 cases of roundworm infection in humans have been reported in one year. Children, in particular, are at risk for health problems should they become infected. A variety of organs may be affected as the larvae migrate through the body. In suitable environments, the eggs may remain infective to humans (and to cats) for years.
Prevention and Control
- Prompt deworming should be given when any parasites are detected; periodic deworming may be appropriate for cats at high risk for reinfection. Adult cats remain susceptible to reinfection with roundworms throughout their lives.
- Pregnant queens should be dewormed in late pregnancy to reduce potential contamination of the environment for newborn kittens.
- All new kittens should be treated by 2 - 3 weeks of age. To effectively break the roundworm life cycle, kittens should be dewormed on the schedule recommended by your veterinarian.
- Cats with predatory habits should have a fecal examination several times a year. Rodent control is desirable since rodents may serve as a source of roundworm infection for cats.
- Prompt disposal of all cat feces is important, especially in yards, playgrounds, and public parks.
- Stool should be removed from litter-boxes at least daily. Litter-boxes can be cleaned with a 1% bleach solution to remove roundworm eggs; rinse well to remove all bleach.
- Strict hygiene is especially important for children. Do not allow children to play in potentially contaminated environments.
>>Return to Top<<
Ancylostoma tubaeforme in cats; Ancylostoma braziliense and Uncinaria stenocephala in both cats and dogs.
Hookworms are (Nematode) parasites which get their name from the hook-like mouthparts they use to attach to the intestinal wall. They are only about 1/8" (3 mm) long and so small in diameter that you have to be looking very carefully to see them.
Despite their small size, they suck large amounts of blood from the tiny vessels in the intestinal wall. A large number of hookworms can cause anemia. This problem is most common in kittens, but it will occasionally occur in adult cats. In general, cats tend to harbor very few hookworms compared to the number carried by infected dogs.
Adult hookworms pass hundreds of microscopic eggs in the cat's stool. The eggs are invisible to the naked eye. Larvae (immature worms) will hatch from the eggs and remain in the soil for weeks or months. If the cat swallows any of these larvae, hookworm infection will be established. The larvae may also burrow through the cat's skin and migrate to the intestine, where they will mature and complete their life cycle.
In dogs, prenatal infection (infection prior to birth) may be a significant problem. Puppies may become infected by the placental blood flow and then later through the mother's milk. Prenatal infection has not been demonstrated to occur in kittens.
For cats, the most significant problems appear related to intestinal distress and anemia. Blood loss results from the parasite sucking blood from intestinal capillaries.
A blood transfusion may be needed in some cats because of the rather severe anemia which can be produced by hookworms. The presence of pale gums, diarrhea, or weakness might suggest the need to specifically determine the cat's red blood cell count. Some cats experience significant weight loss with hookworm infection.
In dogs, skin irritation and itching can be one of the common signs of a heavily infested environment. The larvae burrow into the skin and cause the dog a great deal of discomfort. The most common hookworm of cats does not appear to have this type of burrowing behavior.
Hookworms are diagnosed with a microscopic examination of a small stool sample. Since the eggs are produced on a daily basis, hookworm infection is usually fairly easy to diagnose.
There are several very effective drugs that will kill hookworms. These are given by injection or orally and have few, if any, side-effects. However, these drugs only kill the adult hookworms.
Therefore, it is necessary to treat again in about 2 - 4 weeks to kill any newly formed adult worms that were larvae at the time of the first treatment. Do not use "dewormers" commonly sold over the counter, often these chemicals will make the cat ill and fail to resolve the problem. Over-the counter-wormers can be very toxic and irritating to your cat and should be avoided. The safest and most effective drugs can only be prescribed by your veterinarian.
Since the cat's environment can be laden with hookworm eggs and larvae, it may be necessary to treat it with a chemical to kill them. There are several available that are safe to use on grass.
The type of hookworms which infect cats do not infect humans; however, the larvae can burrow into human skin. This causes itching, commonly called ground itch, but the worms do not mature into adults. Direct contact of human skin to moist, infected soil is required. Fortunately, this occurs rarely if normal hygiene practices are observed.
Prevention and Control
- All new kittens should be treated by 2 - 3 weeks of age. To effectively break the life cycle of the most common intestinal parasites, kittens should be dewormed on the schedule recommended by the veterinarian.
- Prompt deworming should be given when any parasites are detected; periodic deworming may be appropriate for cats at high risk for reinfection.
- All cat feces should be disposed of promptly, especially in yards, playgrounds, and public parks.
- Strict hygiene is important, especially for children. Do not allow children to play in potentially contaminated environments.
>>Return to Top<<
The most common tapeworm of cats (and dogs) is called Dipylidium caninum, which is flea-vectored. Taenia taeniaeformis are are transmitted by predation of rabbits or rodents. The parasite attaches to the small intestinal wall by hook-like mouthparts.
Adult tapeworms may reach 8 inches (20 cm) in length. The adult worm is actually made up of many small segments about 1/8 inch (3 mm) long. As the tail end of the worm matures, the terminal segments break off and pass into the stool. Occasionally, the mobile segments can be seen crawling near the anus or on the surface of a fresh bowel movement.
These segments look like grains of rice and contain tapeworm eggs; the eggs are released into the environment when the segment dries. The dried segments are small (about 1/ 16", or 2 mm), hard and golden in color. These dried segments can sometimes be seen stuck to the hair around the cat's anus.
How cats get tapeworms
First, tapeworm eggs must be swallowed by flea larvae (an immature stage of the flea). Contact between flea larvae and tapeworm eggs is thought to occur most frequently in contaminated bedding or carpet. The life cycle of the tapeworm cannot be completed unless the flea swallows tapeworm larvae. Next, the cat chews or licks its skin as a flea bites; the flea is then swallowed. As the flea is digested within the cat's intestine, the tapeworm hatches and anchors itself to the intestinal lining.
Tapeworms are not highly pathogenic (harmful) to your cat. They may cause debilitation and weight loss when they occur in large numbers. Sometimes, the cat will scoot or drag its anus across the ground or carpet because the segments are irritating to the skin in this area.
This behavior is much more common in dogs than cats. The adult worm is generally not seen, but the white segments which break away from the tapeworm and pass outside the body rarely fail to get an owner's attention! Occasionally, a tapeworm will release its attachment in the intestines and move into the stomach. This irritates the stomach, causing the cat to vomit the worm. When this happens, a worm several inches in length will be seen.
Tapeworm infection is usually diagnosed when the white, mobile segments are seen crawling on your cat or in the stool. Tapeworms are not usually detected by the routine fecal examination performed by the veterinarian. Because of this, veterinarians depend on the owner to notify them of possible tapeworm infection in the cat.
Treatment is simple and, fortunately, very effective. A drug which kills tapeworms is given, either orally or by injection. It causes the tapeworm to dissolve within the intestines. Since the worm is usually digested before it passes, it is not visible in your cat's stool.
These drugs should not cause vomiting, diarrhea, or any other adverse side-effects. Do not use "dewormers" commonly sold over the counter. Over-the counter-wormers can be very toxic and irritating to your cat and should be avoided. The safest and most effective drugs can be prescribed only by your veterinarian.
Control of fleas is very important in the management and prevention of tapeworm infection. Flea control involves treatment of your cat, the indoor environment and the outdoor environment where the cat resides.
If the cat lives in a flea-infested environment, reinfection with tapeworms may occur in as little as two weeks. Because the medication which treats tapeworm infection is so effective, return of the tapeworms is almost always due to reinfection from the environment.
>>Return to Top<<
Tapeworms and pinworms look very similar. However, contrary to popular belief, pinworms do not infect cats or dogs. Any worm segments seen associated with cats are due to tapeworms. Children who get pinworms do not get them from cats or dogs.
Feline tapeworms infections are not common or likely in people. A flea must be ingested for humans to become infected with the most common tapeworm of cats. Most reported cases have involved children. The most effective way to prevent human infection is through aggressive, thorough flea control. The risk for infection with this tapeworm in humans is quite small but does exist
One less common group of tapeworms, called Echinococcus, is of particular concern as a threat to human health. These tapeworms cause very serious disease when humans become infected.
This parasite is harder to diagnose than the tapeworm caused by fleas because the segments are small and not readily seen. Hunters and trappers in the north central United States and south central Canada may be at risk for infection by this worm if strict hygiene is not observed.
Foxes and coyotes (and the wild rodents upon which they prey) are important in the life cycle of this parasite. Dogs and cats may also become infected if they eat rodents carrying the parasite. Another good reason to keep your cat indoors and supervised while outdoors.
Effective flea control is important
- Prompt deworming should be given when parasites are detected periodic deworming may be appropriate for pets at high risk for reinfection
- All pet feces should be disposed of promptly, especially in yards, playgrounds, and public parks.
- Strict hygiene is important, especially for children. Do not allow children to play in potentially contaminated environments
>>Return to Top<<
Whipworms are a very long, slender worm that can reach 4 inches in length. Inlike tapeworms, hookworms, and roundworms which inhabit the small intestine, whipworms colonize the large intestine, particulary the cecum and colon of the cat.
Adult worms pass a football-shaped egg which, when ingested orally, hatches into a larvae, develops into an adult worm and attaches to the colonic wall of the animal. Signs of illness will often be minimal in light infestations, but if enough worms are present, diarrhea, often with blood and mucus and a loss of weight may occur. Your veterinarian may diagnose this as a Whipworm Colitis. Infection by whipworms in cats, however, is quite rare.
>>Return to Top<<
Fleas are without question the most significant external parasites afflicting cats. Fleas can cause life-endangering anemia, particularly in severely infested kittens, and host one of the major tapeworms that infect cats.
Fleas can also transmit plague, a potentially fatal infection caused by the bacteria Yersinia pestis, most cornmonly from infected rodents and rabbits to cats and humans. Rarely, fleas transmit the disease from cat to cat or from cats to other species, including humans and dogs. Although plague is not common in cats, numbers of feline cases as well as cat-associated human cases, have been on the rise since 1977 in the western United States.
But as far as the cat is concerned, probably the most bothersome problem associated with fleas is flea-bite hypersensitivity, an allergic reaction to flea saliva. For the unfortunate cat that suffers from this disorder, Just a few flea bites are often enough to cause a severe skin reaction. Common signs of flea-bite hypersensitivity are itchy skin, scabby bumps and hair loss-but these signs are not always exhibited, and other diseases can have the same symptoms. The only solution for such cats is to prevent fleas from coming near them. This is usually a simple matter if your only pets are cats-keep them indoors-but can be a difficult task for many households with dogs. Anti-inflarnmatory medications can be very helpful, but they are not a cure. They must be given as long as the cat is exposed to fleas, and they can sometimes produce harmful side effects when used long-term.
By parting the fur, you may be able to see these small brownish, wingless insects running about. If the infestation a s fairly light, fleas may be impossible to spot oil the coat, but flea dirt (droppings)-which looks like tiny black pepper flakes-confirms their presence. To find flea dirt, thoroughly comb the coat with a flea comb and look for black flecks entrapped in the teeth of the comb. If you can't tell if the black material is flea dirt or just debris, take a fleck or two and place it on a damp paper towel; if' a red halo forms around the fleck, it is flea dirt.
To control flea infestation, you must treat the environment as well as all the animals in the household. There are many safe, effective, and easily adininistered flea products available from veterinarian Convenient monthly treatments given orally or applied to a small area of the skin are a boon to pet owners because they eliminate fleas not only from their pets for a month at a time but from the indoor environment as well. This is especially important in households where family members (often children) have an allergic reaction to flea bites.
Make certain that any over-the-counter products you use are labeled specifically for rise in cats, as some dog products may not be safe for cats, and follow the directions carefully. Never apply a flea product unless you can monitor the cat closely for at least several hours after administration and do not use more than one product at a time.
>>Return to Top<<
Ticks are small parasites that bury their heads in the skin of' their hosts and stick blood until they look like fat, gray or brown beans. When the ticks can't hold any more blood, they fall off the host and lay thousands of eggs. Heavy tick infestations, rare in cats, can cause anemia as well as skin irritations and infections.
Cats may be parasitized by hard ticks of the family Ixodidae. These ectoparasites which feed only on the blood of their hosts are arthropods, closely related to scorpions, spiders and mites. Ticks have a great potential to act as vectors of protozoa, fungi, bacteria, viruses, rickettsiae, filarial nematodes and spirochetes. Hard ticks have four life stages: egg, larva, nymph, and adult. Larvae and nymphs must feed to repletion prior to detaching and molting.
As adult female ticks engorge, they may increase their weight by more than 100 fold and after detachment may lay thousands of eggs.
Pathogens may be acquired when ticks feed on infected reservoir hosts (often rodents and small feral mammals). In some cases transovarial transmission of pathogens occurs and infected eggs will hatch and produce infected larvae.
The greatest potential for systemic disease occurs when infections acquired in early life stages are transmitted to new hosts when the next stage feeds. Transmission of pathogens and toxins often requires periods of attachment from hours to days and the essentially painless bite of ticks allows feeding times of adequate duration.
Ticks should be removed as soon as possible to limit time available for neurotoxin or pathogen transmission. Most efficient removal is accomplished with fine pointed tweezers. Ticks are grasped close to the skin and gently pulled free.
Species with short, strong mouth parts (e.g., Dermacentor) usually pull free with host skin attached; species with long, fragile mouth parts (e.g., Ixodes) often leave fragments embedded in the feeding cavity. In either case, washing with soap and water is generally sufficient to prevent local inflammation of secondary infection
Tick avoidance requires avoiding environments that harbor ticks. Because ticks may survive on many intermediate hosts, and because suburban living has brought pets into environments frequented by these intermediate hosts, avoidance may be difficult for all but pets kept strictly indoors or for city dwellers.
Other external parasites that can cause skin disease in cats are several species of Cheyletiella mites (large, oval, blimplike parasites visible as small white specks that cause an itchy skin disease known as cheyletiellosis, or "walking dandruff ", plus a number of other species of mites and lice (small, flat, wingless biting parasites that cause itchiness, hair loss, and dandruff). Correct diagnosis and treatment ensure successful management of problerns from external parasites.
>>Return to Top<<
Ear mites Otodectes cynotis are large, white, free-moving psoroptid mites that causes otoacariasis. These are highly transmissible mites that live on the surface of the epithelial lining of the ear canal, or less frequently on the skin surface. Otodectic mites lack specificity among carnivore host species and are responsible for approximately 10% of otitis in dogs and 50% in cats (Griffin, 1993).
The incidence may actually be higher than this because otitis may be produced by low numbers of mites that could go undetected on examination. In addition, mites will often leave the ear canal if severe inflammation or a purulent bacterial or yeast infection develops.
The life cycle is completed in 3 weeks and is initiated with the laying of an egg, which is cemented to a substrate. After 4 days, the egg hatches into a six-legged larva that develops into an eight-legged protonymph in 3 to 10 days. After 3 to 5 days, the protonymph molts into the deutonymph.
After an additional 3 to 5 days, the deutonymph becomes attached, end to end, with an adult male. if a male adult is produced from the deutonymph, the attachment has no significance. However, if a female is produced, she must be fertilized at the moment of ecydysis or she will not be able to produce eggs.
Mites feed on lymph and blood, thereby exposing the host to mite antigens. This may allow the host to become sensitized to mites with the production of immunoglubulin E (IgE) reaginic antibodies.
This sensitization can be demonstrated in 87% of random source cats, which will have immediate wheal and flare response to mite antigens. Probably, almost all cats are exposed to small numbers of mites early in life, with the majority developing immune responses that create an aural environment that is not suitable for mite colonization and clinical disease.
Other cats may have ineffective immune responses that allow mites to colonize and produce clinical disease.S