Hookworms

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The PetStuff Online Newsletter
Volume 1 Issue 3  August 27, 1999


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"Hookworms and Why Dogs are Kept off Beaches"

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...

HookwormLife.JPG (91444 bytes)

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!

Next Week

I would like to continue on with the subject of the worms of dogs and cats and how they can affect humans.    Here is the schedule.

September 3rd - Whipworms and the Neighbors Dog
September 10th - Those Disgusting Tapeworms
September 17th - Demodex Mites & The Red Mange

A Little Pet Humor in Closing

Rules For Cats

Human Guests
Quickly determine which guest hates (or is allergic to) Cats.  Sit on that lap. If you can arrange for particularly bad "tuna breath" (or extra dander), so much the better.

For sitting on laps or rubbing against trouser legs, select fabric which contrasts well with your fur. For example: White-furred Cats go to black wool clothing. NOTE: Velvet takes precedence over all other cloth.

For the guest who exclaims, "I love kitties!", be ready with aloof disdain, apply claws to stockings or arms, or use a quick nip on the ankle.

When walking around the dishes on the dinner table, be prepared to look surprised and hurt when scolded. The idea is to force your humans to reveal that they tolerate this behavior when company is not there.

Always accompany guests to the bathroom. It is not necessary to do anything - just sit and stare. If you do feel active, try turning off the light switch if it is within reach; this is usually good for some laughs. Some Cats with a more prankish disposition like to hide behind the White Drinking Bowl and reach around to pat the human on the behind as s/he is sitting down. This will result in expulsion, but it is worth it!

Rules for Dogs


Chewed up underwear/feminine hygiene products/poop from the backyard is NOT a "toy" to be offered to guests.

Daddy gets embarrassed when I stare at his peeper when he is getting ready for a shower.

I can walk faster than one inch an hour.

I do not need to dribble my last drink of toilet water on Mommy's bedspread.

I will not bury my Gooey Chewy in Mommy and Daddy's bed.

I will not do the "dog sled" (drag my bottom) when guests are present.

I will not hump the feather duster whilst making ungodly noises in front of my humans friends.

I will not lick lotion off my Mom's legs; she doesn't need my help.

Rolling in unmentionable things does not make me more attractive.

Credits

Images used in this publication taken from Hill's Atlas of Clinical Anatomy, Published by Veterinary Medicine Publishing Company, Inc.   A publication donated to veterinarians by the Hill's Pet Food Company to teach clients about their dogs and cats in sickness and in health.   Hill's Pet Food Company produces Hill's Prescription Diets and Science Diet Premium Pet Food

Have A Good Week

Later,  Dr Dan