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Gastrointestinal Parasites… a New Look at a Common
Problem
In order to ensure the health and well being of our pets,
stool examinations for parasite eggs have been part of the veterinary routine
for decades. Although stool examinations have become routine, a new procedure has
recently been presented that has drastically improved the quality of the
results. Starting this October, we at Groton City Animal Hospital will have this
new equipment available for our patients.
Depending on the parasite involved, this new procedure can
dramatically influence the quality of the results. Previous methods for
hookworms only revealed half the number of parasites as the new method. For
roundworms the new method reveals about 100 times more parasites, for whipworms
we can now detect infections where the parasite remained undetected before.
Detecting the actual parasite burden of our pets is important to the pet’s
health, but to protect human health as well. Undetected infection can lead to
animal and human illness.
Zoonosis (zo-e-nos-sis)
= Any disease that can be passed from animals
to humans.
Although all people are at risk for developing
zoonotic infections certain groups of people may be at greater risk; children
,elderly, people with immune compromise disorders (diabetes, HIV, organ
transplant recipients or people undergoing chemotherapy), people who work with
animals at shelters, veterinary hospitals or in other animal related
occupations. In the case of intestinal parasites, transmission occurs
through accidental oral ingestion of parasite eggs, from accidental ingestion of
an infected flea or by penetration of the skin by parasite larvas (hookworms
only).
You may not even recognize any illness or see obvious
symptoms in your pet until it is too late. Parasite eggs are shed by
animals, even those that appear to be well and energetic. Most intestinal
parasites can multiply at an alarming rate, so even a single intestinal worm can
become a fast-growing problem.
Contaminated pet droppings can carry infective eggs, the
source of most pet-to-human infections. Follow these steps to help protect
your pet and family:
- Have your pet examined regularly by your
veterinarian, who will recommend a screening test for parasites to be
performed twice a year or more often, depending on your pet's lifestyle and
risk factors.
- Deworm your pet on a regular schedule
recommended by your veterinarian. This removes intestinal parasites
and prevents further contamination of the environment.
- Practice good hygiene. Wash hands
regularly, especially after handling pets or cleaning up pet waste.
- Remove pet droppings from your yard at least
every 2-3 times a week - daily is best.
- Wash all fruit and vegetables thoroughly
before eating.
- Keep pets flea-free. Ingestion of
infected fleas can transmit tapeworms to animals and people.
- Do not allow children to go barefoot or sit
or lie on playgrounds where they may be exposed to animal stools.
- Clean cat litter boxes daily and wash hands
afterward.
- Do not drink water from streams or other
sources that may be contaminated with animal feces.
- Keep pets clean.
Facts about Intestinal Parasites:
- Zoonotic parasites are transmitted primarily
from a contaminated environment, not from normal contact with your pet.
- Parasite eggs cannot be seen by the naked eye
even though they may be present in the feces of an infected animal.
- One female roundworm can lay up to 100,000
eggs in a day, and one female hookworm can produce up to 20,000 eggs in a
day.
- In just one week, two puppies infected with
roundworms can shed more than 20 million eggs and contaminate a
2,800-square-foot backyard.
- Certain parasite eggs can survive in soil for
years.
Roundworms (ascarids)
Toxacaria (dog and cat roundworm):
Roundworms look like a piece of spaghetti with more tapered ends, and may be
found in either stool or vomitus. Roundworms are a common intestinal parasite in cats and dogs nationwide.
National studies have found that between 90-100% of puppies/kittens under 3
months of age and up to 20% of adult animals not regularly treated for worms
carry this infection. One adult roundworm can produce 100,000 eggs per day.
Heavily infected animals can shed millions of eggs per day in their stool.
Puppies and kittens have a high incidence of infection because they acquire the
infections from their mother either prenatally through the placenta or soon
after birth through larva present in the mother’s milk. Infected puppies then
shed large numbers of eggs in their stool thus making the nursing mother very
susceptible to reinfection –
thus continuing the cycle.
Roundworm Disease in Animals:
On infection, the larvae not only affect gastrointestinal tissue, but
often migrates into other tissues of the body where they "rest" and lie dormant
for periods of time up to years. When the animal is stressed , such as during a
pregnancy, the larva awaken and mature and become infective again.
Eggs shed in the stool of infected animals contaminate the environment by
getting into the soil where they can survive for long periods of time and serve
as a route for infection to any animal that walks or plays in the soil.
Infected animals may have a "pot bellied" appearance and no other signs. Others
commonly have soft stool, diarrhea, or vomiting. Severe cases of worms can
result in malnutrition, dehydration, and intestinal obstructions or twists which
may lead death.
Roundworm Disease in People:
Roundworm larvae are ingested by a person due to inadequate
hand washing, handling soil contaminated with animal feces, or even by "puppy
kisses". Most human infection goes undetected, however, in some people the
larvae migrate through the tissues to the eye or other organs. When the larva
migrates into the eye it destroys the tissue which can lead to partial or total
blindness. Migration through other tissue in the body may cause nausea, fever,
edema and even seizures.
Baylisascaris (raccoon roundworm):
The raccoon roundworm deserves mention because it has been shown
to cause infection in other mammals including dogs and humans. This larva is
found in soil (yards, gardens, and sandboxes). Infection of this larvae can
cause asymptomatic disease as well as severe neurologic disease (due to
migration through the brain), seizures and death.
A common question asked concerns the frequent recurrence
of roundworm infestations. Multiple treatments are commonly required because of
the variable maturation rate of the worms. Only adults in the intestine are
removed by the medication. Other worms still in the larval stages are migrating
in other body tissues and are not killed by dewormers.
Hookworms (ancylostoma)
Hookworms are very common throughout the United States and
the world. Approximately 20% of all pets are believed to carry the infection.
The larvae are commonly found in damp, sandy soil, including shady areas under
bushes, crawl spaces, under porches, sandboxes, and beaches. Infection can
result from soil contamination and from mother to newborn via the milk. They are
difficult to see with the naked eye due to their size, color and fragility.
Hookworms attach themselves to the wall of the intestine and cut a hole in it so
that bleeding occurs. The parasites then suck the blood for their nutrition. A
heavy infestation in small puppies can cause death from blood loss. This
parasite is much more common in dogs than
Disease in Animals:
Hookworm infection in animals varies in severity from asymptomatic
infection to severe anemia and even death. All age groups can be infected and
have severe or fatal disease. Young animals are, however, at the greatest risk.
Animals infected in the first days of life with as few as 50-100 worms may
result in fatality. Puppies and kittens usually look healthy the first week but
soon deteriorate, become pale, have dark or bloody diarrhea and often die by the
end of the second week. Hookworms are spread to your pet in several ways. They
can be spread to pups/kittens just after birth through the colostrum (first
milk) from their mothers. This parasite can also be transmitted to your pet if
they eat grass that contains the larvae. Just walking in damp grass or sand if
the larvae are present can permit them to be present on the skin and then
penetrate and cause an infestation. Hookworms can be very tough to eradicate.
Disease in People:
Infected larva from the soil can penetrate and migrate in the skin of
humans. This causes a condition called cutaneous larva migrans of "creeping
eruption". Some larva may also enter the gastrointestinal tissue and create an
intestinal disease called eosinophilic enteritis.
Whipworms
Whipworms are parasites
that live in the cecum, an organ at the junction of the small and large
intestines. They cause an irritation and inflammation of the cecum and large
bowel with resultant diarrhea (sometimes bloody) and weight loss. These worms do
not lay as many eggs as the others do, and therefore can escape detection more
easily. These eggs are quite resistant and may require housing the pet in a
different area for a time if there is a large number of eggs in a small area
(where a dog has been tied or kenneled).
Tapeworm Infection
The flat worms you may see in your pet's stool are
pieces of a tapeworm. The actual tapeworm can be up to 3 feet long and attach to
the interior of the wall of the intestine. Even though they do attach themselves
to the intestine, they do not suck blood from the wall of the intestine, instead
they just remain in the intestine and absorb their nutrients from the food your
pet has eaten and digested for themselves, and use if for their own. Their
presence in the GI tract causes no pain, but it takes more food to keep your pet
in good condition. This can result in weight loss, loss of appetite, vomiting or
diarrhea. The little pieces that you sometimes see which look like rice when
they are dried, are flatter than roundworms. The tapeworm is made up of segments
which contain the eggs making it easy to miss in a routine stool check because
the eggs are not mixed in with the stool.
Tapeworms differ greatly from the other worms dogs and
cats can get in that they require an intermediate host for transmission. In
other words, a portion of the life cycle must take place in another animal.
There are two tapeworms that are common in this area. The most common is
Diplidium caninum, the flea tapeworm, and since it is the most common, when you
see evidence of a tapeworm infestation, look for fleas. They are passed to the
pet by licking their coats and removing infested fleas from themselves. The
other but less common tapeworm is Taenia sp. The intermediate host for this is
the rabbit and occasionally rats or mice. This is a tapeworm of the hunter that
eats its quarry.
Humans can be infected by one of the tapeworm species.
Infection can be from direct contact with infected pets or from infected soil in
the environment. Infection results in cysts in the liver, lungs or other tissues
of the body. Although this species has only been documented in the western part
of the country, recent cases as far east as Ohio have been reported.
Coccidia
Coccidia are one celled animals (protozoans)
that reproduce inside the cells that line the intestine. They are found
everywhere dogs have been and it is necessary that puppies and kittens develop
immunity against them in order to have no possibility of future problems with
them. The difficulty comes when young pups and kittens come in contact with
large numbers of them before immunity is formed. The method of treatment is to
reduce the numbers of coccidia in the intestinal tract to numbers the pets can
handle and allow them to develop an immunity. So, in the absence of diarrhea,
finding these in stool samples is not considered a problem for that patient,
unless there is evidence of clinical disease in littermates.
There are no medications that will kill
coccidia, only the pet's immune system can do that. But we can give medicines
called "coccidiostats" which can inhibit coccidial reproduction. Once the
numbers stop expanding, it is easier for the pet's immune system to "catch up"
and wipe the infection out. This also means, though, that the time it takes to
clear the infection depends on how many coccidia organisms there are to start
with and how strong the pet's immune system is. A typical treatment course lasts
about 1-2 weeks but it is important to realize that the medication should be
given until the diarrhea resolves plus an extra couple of days. Medications
should be given for at least 5 days, sometimes as long as a month is needed.
Giardia
Giardia is another protozoan parasite that is becoming
more common in this area. It is spread through drinking infected water and
causes profuse watery, sometimes bloody diarrhea. This parasite can be difficult
to diagnose because of their fragility and small size. There is a new test that
can be performed in out office that is much more sensitive that can be used to
establish a diagnosis.
Deworming Guidelines for Dogs
Puppies -
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Every 2 weeks until 3 months of age
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Once a month from 3-6 months of age
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Four times a year after 6 months of age
Adults -
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Treat regularly, considering potential exposure to parasites
and prepatent periods
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Strongly recommend doing a fecal yearly
Lactating Dogs -
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Should be treated concurrently with puppies
Newly Acquired Puppies or Dogs -
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Immediately, then repeat after 2 weeks, then follow
guidelines above.
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