Dr. Carla Hubbard-Erickson
There are many parasites that can affect cats and dogs. Most of these
are commonly referred to as "worms." The problem with "worms"
is that they have a small potential to cause illness in people as
well. This is why it is important for all of us to be aware of the
ways to prevent parasites in our pets. There are also some parasites
that are not "worms" that can be of concern also. I will
go through a basic list of some of the more common disgusting critters.
Toxocara canis: "round worms" - These are the nasty little
creatures that we will most often see in puppies and kittens. They
will appear to us as 'curled-up strands of spaghetti'. Sorry for the
food-related description, but it is accurate. If puppies and kittens
are severely infested with these, they can pass them in their bowel
movements, or even vomit them up. If you don't see evidence of this,
that doesn't mean your pet is free of round worms. As with all of
the intestinal parasites, the only way to accurately check for them
is to have a fecal sample examined microscopically by your vet. Even
if adult worms are not being shed in the feces, the eggs of the parasites
will usually show up under the microscope.
Puppies and kittens can be born with these parasites, or they can
be passed from the mother shortly after birth. Animals should be treated
for these worms at 2, 4, 6 and 8 weeks of age. Some veterinarians
have a slight variation of this schedule. Check with your vet for
additional information. A routine check of a stool sample should be
done every 6-12 months for pets to ensure that they are parasite-free.
The human diseases associated with this parasite are called Visceral
Larval Migrans and Ocular Larval Migrans. These could occur if a human
were to ingest the egg of the parasite, and the larval stage migrate
through the intestinal wall or into the eye. This is extremely uncommon
in this country (although not impossible), and requires oral contamination
with infected animal feces. Unfortunately, in the U.S., this is most
usually associated with children playing in uncovered sand boxes.
To help prevent contamination from household pets, owners should pick
up and dispose of the feces in yards promptly, before the ova have
a chance to become infective.
Ancylostoma caninum: "Hook worms" - These nasty critters
have hooked mouthparts that bury into the animals' intestinal lining
and live on the intestinal blood supply. We will probably not see
these worms in the feces. We must rely on fecal examination by the
veterinarian to diagnose hookworms. In our puppies, this parasite
will cause intestinal distress, diarrhea, and often severe and life-threatening
anemia. Puppies can get these worms from their mother - in utero,
or from the milk. Older puppies, dogs and occasionally cats can get
them from ingesting infective larvae.
In people, hookworms can cause 'Cutaneous Larval Migrans'. This occurs
when larvae penetrate through the skin (usually via bare feet), and
migrate under the epidermis. This parasite usually will cause no real
harm, but can cause intense itching before it is destroyed by the
immune system.
As with roundworms, treating puppies at an early age, checking fecal
samples often, prompt disposal of fecal matter, and prevention of
soiling in playgrounds will decrease human exposure to the infective
larvae.
Dipylidium caninum: "Tapeworms"- These parasites appear
to us like 'grains of rice' on the fecal matter. Again, I apologize
for the food-related example. They are either single 'grains', or
they can be passed as a longer section made up of several of the 'grains'.
These worms rarely cause any real problems, other than mild irritation
and owner horror. These parasites are transmitted to animals (and
to humans) by eating an infected flea (the intermediate host for tapeworms).
Human infestation usually causes no real problems, and again is most
common in children. The prevention of dipylidiasis in animals and
humans is best accomplished with flea control. This is especially
important now because of the overabundance of fleas.
Trichuris vulpis: "whipworms" - These are parasites that
will cause much discomfort to animals, but no problems for people.
Whipworms will attach themselves to the lining of the colon primarily,
and will result in colon irritation - colitis. Colitis will show up
in animals by a straining to produce a bowel movement. Dogs will have
a bowel movement, then move a little and try again - and again. They
may not produce additional feces, or they can produce a slime-coated
or bloody stool. Colitis can be very serious in animals. This problem
should always be checked by a veterinarian. Whipworm is another parasite
that can only be found by fecal examination. Animals acquire this
parasite by ingesting infective larvae from the ground where other
animals have passed feces.
Microsporum canis: "Ringworm" - Although this problem is
not actually a 'worm', I will discuss it here because of its name.
Ringworm is actually a fungal infection. It is most often associated
with cats - especially cats housed in high numbers as in a cattery.
The animals affected by this infection will have hair loss in different
places on the body, and will often have a secondary bacterial infection
at these areas. The only way to diagnose ringworm is by veterinary
examination. Some forms of ringworm will fluoresce under a black light
- others must be found with a fungal culture taken by your vet.
People can get ringworm from direct contact with an infected animal.
Owners should always wash their hands well following handling of an
infected dog or cat. On people, this infection will show up as a circular
lesion with an outer ring of red - hence the name of 'ringworm'.
While prevention is the best method of parasite control, all of these
problems can be treated if infection does occur. It should also stand
to reason that people (and animals) with diminished immune systems
will be more susceptible to infection by any and all of these problems.
That would include people on chemotherapy and people suffering from
AIDS.
There are many other types of parasites that affect animals and also
people. Hopefully we will be able to discuss more of these in the
future. Are we having fun yet?!?!
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