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"Hookworms and Why Dogs are Kept off Beaches"
Reprinted with permission from Dr Dan.
You can read this article and many more by visiting
http://www.dr-dan.com/
This week we
would like to discuss hookworms, another extremely common intestinal
parasite of dogs and cats. Typically, these are invisible to the
unaided human eye. They are about 1/2 inch long and very, very thin.
Since they are "bloodsuckers", 300 adult worms can drain 10% of the
pet's blood per day. This can cause extreme stress or even death of the
pet.
What
are they?
If you look at
the picture below (the inset) you will notice that the "business end" of
the Hookworm is shaped like a tiny goblet with three sets of teeth. The
goblet-shaped mouth is very hard and resists collapse as the worm sucks.
The Hookworm grasps onto the inner surface of the small intestine with
the teeth and then pierces a blood vessel. An anti-coagulant saliva-like
substance is released which prevents the blood from clotting. Each
hookworm can suck 0.1cc of blood per day. If they release the wound
continues to bleed.
How
do our pets get Hookworms?
Kittens or
puppies may be born with Hookworms! Hookworm larva are tiny enough to
migrate through the placental blood supply to the fetal lungs. Soon
after birth, the juvenile Hookworms are coughed up and swallowed. They
then mature in the small intestine; attach to the intestinal wall and
begin sucking blood and laying eggs.
A second source of infection is through the mother's milk -
Hookworm larva can gain entry into the mammary glands and be passed to
the puppies or kittens as they nurse. The larva then mature in the
intestine to form blood sucking adults.
The third possibility is if the pet should swallow a Hookworm
larva found in the environment (like on a blade of grass, a toy, water
or food dish). The Hookworm larva mature to adults in the intestine as
above. Soon after feeding on blood the Hookworm adults begin laying eggs
which pass with the feces. Under favorable conditions (moisture and
warmth) the eggs hatch within 12 to 18 hours and a tiny juvenile
Hookworm emerges. This larva is encased within a sheath that offers
protection against dessication and ensures long life in the environment.
The larva reside in moist areas of the soil and overlying vegetation.
The most important mode of transmission is unique! I
mentioned above how the eggs pass with the feces and hatch within 12 -
18 hours on moist ground. The newly hatched larva then become
free-living organisms which thrive in moist soil or on damp grass awns.
Another interesting thing is that the larva can live for many weeks
without food. These free-living larva are able to penetrate the
intact skin of dogs or cats passing by or as a pet lies on the
ground the heat excites the larva and they go right through the thin
skin of the ventral abdomen. Picture this! You take your dog on a walk
in a park where Hookworm infested dogs have deficated. As your pet
passes through the wet grass an infective juvenile Hookworm brushes onto
the paw. The larva easily penetrate the skin and follow a blood vessel
to the lungs. From there the worm is coughed up and swallowed to mature
in the intestine; begin sucking blood and laying eggs.
Lost?
Maybe a graphic will help...
What
are the signs of Hookworm infestation?
Signs may
include any or all of the following: Inapparent infestations;
nonspecific diarrhea; dark black (tarry) diarrhea; bloody diarrhea;
vomiting; poor or no appetite, pale mucous membranes in the mouth and
generalized pallor; weakness, emaciation and poor growth. Anemia can be
so severe as to cause death.
What
is the treatment?
It is easy to
get rid of Hookworms. Just give any effective oral wormer. My
favorite is any brand with pyrantel pamoate as the active ingredient.
This is generally well tolerated by the pet, safe and effective. If the
animal is severely anemic, blood transfusions and supportive care may be
required. It is best to worm breeding female dogs and cats before
breeding and again 3, 6 and 9 weeks after whelping. Juveniles migrating
through the body will not be killed by conventional wormers. This is
why we like to worm puppies and kittens twice three weeks apart and then
check a fecal specimen three weeks later. This allows all migrating
juveniles to reach the intestine where they are easily killed. Since
Hookworm eggs and larva build up in damp soil, often times the dogs tied
out on dirt or in soil runs need to be moved to a non-infested area to
prevent reinfection. If this is impossible and the pet keeps becoming
reinfected, I suggest keeping the dog on Filaribits Plus (a daily
heartworm preventative with a low level wormer included which kills
Hookworms, Roundworms and Whipworms) for a year or more while the
Hookworm larva and eggs die off. Concrete surfaced runs or runs with
deep pebble coverings allow the surface to dry allowing sunlight to kill
the larvae. Fecal Examinations: Young dogs and cats should have a fecal
floatation done twice a year to detect Hookworm eggs.
Why
dogs are kept off of beaches?
You may have
figured it out already. Hookworm larvae love warm, damp, sandy soil!
If a Hookworm infested dog deficates on a beach the eggs soon hatch and
the larvae enter the sand. When a human lies on such a spot the
Hookworm larva can penetrate the intact skin just as it happens in the
dog or cat. Since we are an unnatural host, the larva never make it to
the intestine to become blood-sucking adults. They just move around a
bit under the skin, die and cause a nasty inflammatory reaction. The
result? We get itchy little red bumps on our skin which may form
scabs. In the old days, when houses had crawl spaces under them, the
pets would often deficate under the house. When the plumber worked on
the piping under the house he soon found little itchy bites all over his
skin. For this reason, human infection is sometimes called the "plumbers
itch". Other names include "creeping eruption" or the more scientific
name "cutaneous larva migrans". A good reason for keeping dogs off
beaches and out of sand boxes and gardening areas.
Be Safe - Be Sure - Have Your Vet Check Your Pet's Feces for
Intestinal Worms Twice a Year!
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