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CANINE WHIPWORMS
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These worms are
1-3/4 to 3 inches long. They cause symptoms of diarrhea, weight loss, anemia,
dehydration, abdominal pain and mucus laden stools streaked with blood.
Whipworms
THE PET HEALTH LIBRARY
(Trichuris
Vulpis and relatives)
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Adult whipworm
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This worm is one of the
"big four" intestinal parasites with which our canine friends must contend:
roundworms, tapeworms,
hookworms, and whipworms. The whipworm that
affects dogs (Trichuris vulpis) is substantially smaller than the other worms
(a mere 30-50 mm in length, about two inches maximum) and is rarely seen as
it lives in the cecum (the part of the large intestine where the small and
large intestine meet). The head (or more accurately, the digestive end of
the worm) is skinny versus its stout tail (or reproductive end), which gives
the worm a whip shape, hence the name.
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In the host’s digestive tract, food passes from mouth to esophagus to
stomach to small intestine to large intestine to rectum and then to the
outside world. This means the large intestine is one of the last stops for
nutrients and by this point in the journey, nutrients have largely been
broken down and absorbed. The large intestine (also called the colon) serves
to absorb water, store fecal material, and provide a home for a spectacular
number of bacteria that are able to digest leftover food. The large intestine
is the home of the whipworm. The adult worms bite the tissue of the intestine,
actually embedding their heads inside, and suck blood there.
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Whipworm egg isolate from a stool
sample. Note the characteristic double plug appearance.
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Whipworms developing in the soil.
Note the characteristic plugs on either end of the egg.
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Eggs are laid inside the large intestine and pass with the stool. Once
in the outside world, the eggs require about 2 to 4 weeks to form embryos
and become capable of infecting a new host. (This means that contaminated
soil is the source of infection, not fresh feces.)
The new host is infected by consuming the egg, usually during grooming.
The egg hatches in the small intestine releasing a larva. The larva dives
into the local glandular tissue and after about a week emerges into the
small intestine and is carried downstream into the large intestine with
the digested food. Once in the cecum or large intestine, its permanent home,
it embeds in the tissue there, and after a total 74 to 87 days from the
time the egg was swallowed, the young whipworm is ready to mate.
A few whipworms generally do not pose a problem for the host but if large
numbers of worms are embedding themselves in the large intestine tissue,
tremendous inflammation can result leading to a bloody, gooey diarrhea. Usually
there is not enough blood loss to be dangerous but the diarrhea readily becomes
chronic and hard to control. A second syndrome of infection has emerged but
is not well understood, this being symptoms mimicking those of Addison’s disease (hypoadrenocorticism).
Here, a waxing and waning weakness with inability to conserve salt ultimately
creates a dehydration crisis. The syndrome mimics Addison’s disease in every
way except that testing for Addison’s disease will be negative and deworming
yields a complete recovery.
Because female whipworms only periodically lay eggs (whereas other female
worms lay eggs continuously), a fecal sample tested may easily be negative
for eggs. This makes the confirmation of a whipworm infection a challenge.
It is common to deworm for whipworms if the symptoms are suggestive of the
whipworm presence even if the fecal test is negative. Most common deworming
agents do not work on whipworms so something special must be selected. The
most common products are fenbendazole(Panacur®),
and febantel (Drontal Plus®). Because of the long maturation cycle of
young worms, a second deworming some 75 days or so after the first deworming
is needed to fully clear the infection (easy to forget). Often another deworming
in between these doses is recommended to further control the whipworm numbers.
More recently, regular heartworm prevention products have been developed
to remove and control whipworms: Sentinel and Interceptor both will cover
whipworms and their regular use covers the second deworming as well. Heartgard
products do not carry a high enough dose of ivermectin to kill whipworms,
though at other doses ivermectin could be used with appropriate cautions.
Soil contaminated by whipworm eggs is contaminated for years. It is virtually
impossible to remove the eggs from the soil or kill them. Happily, however,
this is one pet intestinal parasite that is not readily transmissible to
humans.
Feline Whipworm Infection
There are species of whipworms that can infect cats: Trichuris serrata
in North America and Trichuris campanula in Europe. Cats are clean animals
and fastidious around feces, and they rarely get infected. When they do,
worm numbers are so small that symptoms hardly ever occur. Whipworms are
more of an interesting incidental finding in cats when whipworm eggs happen
to come up on a routine fecal check. In other words, feline whipworm infection
is generally not considered to be much of a problem.
Copyright 2007 - 2008 by the Veterinary Information
Network, Inc. All rights reserved.
This work was originally published by Veterinary Information Network,
Inc. (VIN)
and is republished with VIN's permission.
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The above information is simply informational.
It's intent is not to replace the advice of a veterinarian nor to assist
you in making a diagnosis of your pet. Please consult with your own veterinarian
for confirmation of any diagnosis. Your pets life may depend on it.
