INTESTINAL PARASITES OF DOGS AND CATS

There are six major intestinal parasites of dogs and cats.  Two types of examinations are used to identify these.   A fecal flotation exam will help to identify hookworms, roundworms, whipworms, tapeworms, and coccidia.  A direct fecal smear may also reveal these parasites, but is more commonly used to identify giardia infection and bacterial overgrowth.  Both types of tests are recommended for puppies and kittens and any animal having diarrhea.

HOOKWORMS (Ancylostoma spp):  These worms are most commonly seen in young dogs and cats.  Adult worms live in the small intestine.  The eggs pass out of the body in the stool.  Animals become infected with hookworms by eating infective eggs or larvae;  penetration of footpads or skin by larvae;  transmission through the milk while nursing;  or, transmission from the mother into the fetus while still pregnant.  It takes three weeks from the time of infection until eggs are passed into the stool.  Hookworm infection can cause a severe and sometimes fatal anemia in the young, weak, or malnourished animals.  Clinical signs are weight loss, diarrhea, and bloody, tarry stools.   Sometimes the worms are seen in the feces.  Treatment consists of oral deworming medication and correction of any anemia.  A follow up treatment is given 3 weeks later.  The worms look like long strings of spaghetti and usually will come out in the feces once the dewormer is administered.  All fecal material needs to be picked up and disposed of for the next 5-7 days during treatment.  Any other pets exposed to hookworms should also be treated.  Several heartworm preventives contain added medication to help prevent re-infection with hookworms. 

Public health significance:  The hookworm larvae can penetrate human skin and potentially cause a skin problem called ‘cutaneous larval migrans’ or ‘creeping eruption.’  No one should be barefoot for 5-7 days while the pet is being treated for hookworms.

ROUNDWORMS (Toxocara spp):  These worms are also comonly seen in young dogs and cats.  The adults live in the small intestine and the eggs are passed in the stool.  Animals are infected by ingestion of other infected animals (rats);  or, by pre-natal infection.  Eggs are passed in the stool 3 weeks after infection.  Infection with roundworms can cause poor hair coat, diarrhea, ill-thrift, pot-bellied appearance, and sometimes secondary bacterial pneumonia.  Worms can sometimes be vomited up or seen in the feces.  Treatment is with an oral deworming medication with a follow up dosage in 3 weeks.  All fecal material needs to be picked up and disposed of for the next 5-7 days.  Again, the worms will be seen in the stool and they look like spaghetti.  Most heartworm preventives contain medication to help prevent re-infection with the worms.

Public health significance:  Roundworm larvae can penetrate human skin.  The migrating larvae can affect various organs in the body—causing mechanical damage and also granulomas to form.  This disease is called ‘Visceral larval migrans.’  No one should be barefoot for 5-7 days following treatment.

WHIPWORMS (Trichuris sp):  This worm is diagnosed in dogs 3 months of age or older.  The adults live in the large intestine and eggs are passed in the feces.  Diagnosis can sometimes be difficult because whipworms are not prolific egg-layers.  Infection is via fecal-oral transmission.  Eggs do not appear in the feces until 3 months post-infection.  Clinical signs that can be seen are weight loss and diarrhea (+/- blood).  These worms are usually not seen in the stool.  Treatment consists of an oral deworming medication with a follow up treatment in 3 months.  One of the monthly heartworm preventives will also prevent re-infection with this parasite.

TAPEWORMS (Dipylidium and Taenia spp):  The adult cestodes live in the intestine of dogs and cats.  The Dipylidium sp is obtained by eating an infected flea.  The Taenia sp can be transmitted by eating infected small mammals (rats).  Diagnosis is by visualization of the small, ‘rice-like’ worms in the stool (most common method);  or seeing the eggs on a fecal flotation exam.  The eggs and worm segments are inconsistently shed in the feces.  A negative fecal flotation exam does not completely rule out the possibility of tapeworm infection.  Clinical signs are rare since tapeworm infection rarely causes a problem.  Some clinical signs can be unthriftiness, shaggy coat, irritability, diarrhea, or lethargy.  Treatment is via oral deworming medication or an injection.  Control can be achieved by preventing exposure to fleas. 

Public health significance:  Problems are rare.  People can become infected with the Echinococcus and Taenia spp by association with infected dogs or infected meat.

GIARDIASIS:  This is a common protozoan of all animals.  It lives in the small intestine.  Infection is via the fecal-oral route.  The incubation period is 1-2 weeks.  Clinical signs can be inapparent, continuous, or persistent with diarrhea and weight loss.  Several examinations are sometimes needed to identify the organism.  Treatment is with oral medication to all exposed pets.

Public health significance:  People can become infected with this protozoa by fecal-oral transmission, which includes drinking untreated water (rivers and streams).

COCCIDIOSIS (Isospora and Eimeria spp):  Different species of coccidia infect all animals.  Transmission is fecal-oral and usually due to unsanitary conditions.  It is commonly seen in the young and immune suppressed animals.  Clinical signs can be inapparent or entail weight loss, lethargy, and a mucoid (+/- blood) diarrhea.  Treatment is by oral medication for 10 days.  All exposed pets should be treated.  Sanitary measures should be taken and raw meat should not be fed. 

PREVENTION: 

• Fecal examination of your pet’s stool should be done every 6-12 months.

• Use specific dewormers for the type of parasite present, as determined by microscopic fecal examination.

• Over-the-counter deworming medications may not always be effective.

• Remove feces from your lawn, street, or kennel daily.

• Exercise your pets in grassy areas not frequented by other animals.

• Prevent your pet from eating rodents—such as mice, rats, and rabbits.

• Prevent your pet from eating earthworms (roundworm infection).

• Control fleas!

• Deworm female pets before breeding and again after whelping to prevent infection of newborn pets.

TOXOPLASMA:  This is a coccidial parasite which infects cats.  It is important because of its zoonotic potential.  If women are exposed to Toxoplasma for the first time while pregnant, their baby can have serious congenital problems.  If a woman has already been exposed, there is no danger.  Toxoplasma is shed in the fecal material of cats.  It is not contagious until it has sporulated, about 3 days after being shed in the feces.  HOWEVER, more people get Toxoplasma by eating improperly washed vegetables and improperly cooked meats.  

Do pregnant women need to get rid of their cats?  NO.  Chances are that they have already been exposed.  A blood titre can determine this.

Can pregnant women clean the litter boxes?  Yes.  As long as the boxes are cleaned DAILY, there is no time for the coccidia to sporulate in the feces.  Of course, if there is someone else who can do the cleaning, why not?

Note: This article is provided by Claws & Paws Veterinary Hospital® for informational purposes only.