Monday, November 3, 2014

Why does my cat have grains of rice in its fur? - Tapeworm infection in Cats

A single tapeworm egg in a stool sample


What are tapeworms?

Tapeworm segments in the fir under a cat's tail
The most common tapeworm of cats (and dogs) is called Dipylidium caninum.  This 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.

Cats may also become infected with another type of tapeworm called Taenia spp. that is acquired by eating rodents.

How did my cat get tapeworms?

First, Dipylidium tapeworms 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.

Dipylidium egg packet
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.

What kind of problems do tapeworms cause for the cat?

Several segments of a Taenia tapeworm
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.

How is tapeworm infection diagnosed?

Tapeworm infection is usually diagnosed when the white, mobile segments are seen crawling on your  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.
cat or in the stool.

How are the tapeworms treated?

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.

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.

How do I tell tapeworms from pinworms?

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.

Are feline tapeworms infectious to people?

Dipylidium Lifecycle
Yes, although infection is not common or likely.  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. Risk for human infection with Taenia tapeworms is extremely unlikely, since it is very difficult to accidentally eat a rodent!

Echinococcus Lifecycle
Another 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 Dipylidium 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.  When eggs of Echinococcus are passed in the feces of the dog and cat, humans are at risk for infection.  Free-roaming cats and dogs may need to be periodically treated with tapeworm medication.  Rodent control and good hygiene are important in  preventing the spread of this disease to humans.  As with the more common tapeworm, infection with Echinococcus is infrequent but possible.

Taenia lifecycle

What can be done to control tapeworm infection in cats and to prevent human infection?

1.         Effective flea control is important.
2.        Prompt deworming should be given when parasites are detected; periodic deworming may be  appropriate for pets at high risk for reinfection, such as cats that hunt or venture outside.
3.         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.

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