Camino Animal Clinic #H

Adult hookworm	The adult hookworm lives in the small intestine of its host. It hangs on to the intestinal wall using its 6 sharp teeth and unlike other worms who just absorb the digested food through their skin as it passes by, the hookworm drinks its host’s blood. The adult worm lives and mates within the host and ultimately, the female worm produces eggs. Hookworm eggs are released into the intestinal contents and passed into the world mixed in with the host’s stool.	Hookworms living inside the intestines

The egg hatches in the environment and develops from a first stage larva (the hatchling) to a second stage larva and finally a third stage larva which is ready to infect a new host.

The larva can infect its new host in several ways. One way is to penetrate the host’s skin directly through the feet or belly or whatever part of the skin is touching the ground. Another way for the larva to gain entry to the new host is to be present in soil that is licked and swallowed by the host as it cleans itself.

Once the larvae are inside the host, they make their way to the intestine where some worms simply stay and mature into adulthood. Other individuals tunnel out of the intestine, and migrate to the lung tissue. In the lung, the larvae develop into 4th stage larvae and when they are ready they break out of the lung, climb up the trachea, get coughed into the throat and swallowed. Once back in the intestine, these well-traveled worms will complete their maturation to adulthood.

Not all the worms that begin this treacherous migration complete it. As they emerge from one tissue to move on to the next, some fall into a state of arrest where they go dormant and encyst. These larvae remain inactive but periodically some will emerge and complete their migration.

Hookworm infection can be lethal to young puppies. A young puppy is growing and that includes making enough new blood to serve not only its needs but the needs of its growth. Growing requires a tremendous red blood cell production from the puppy’s bone marrow, yet in the hookworm infected puppy this process is being sabotaged from within.

Infected puppies are commonly pale, weak, and have long-standing deficiencies. They may or may not have diarrhea. Symptoms include lethargy, dark stools or diarrhea, weakness and vomiting. In severe cases they are anemic and debilitated, especially the older and younger pets. The larvae might even irritate the skin when they penetrate between the toes and pads.

The mucous membranes e.g., gums, will appear pale, the animal will become weak, and sometimes black, tarry stools can be seen. There may be vomiting and diarrhea. Growth in young animals is stunted, and the hair coat may appear dull and dry. In severe infestations, animals may cough or develop pneumonia as the larvae migrate through the lungs. Animals may become emaciated and eventually die from the infection.

Infection of the very young puppy can occur in two ways not addressed in the above description of transmission and will be described now. Typically an infected mother dog will have encysted larvae all around her body. Throughout the adult dog’s life, some larvae will awaken, break out of their cysts, and complete their migration to the GI tract.

The hormones of pregnancy unfortunately serve as little wake-up calls to encysted hookworm larvae only this time, the little worms migrate to the unborn puppies and to the mammary gland.

Some members of the litter will be born infected. Others will become infected by drinking the contaminated milk of their own mother. Others will become infected from the soil of their own nest which will quickly become contaminated with the stool of the infected litter.

It is clear why puppies are at a special risk over adult dogs when it comes to hookworms. The Center for Disease Control has recommended automatically deworming puppies for hookworms beginning at age 2 weeks in areas where hookworms are common.

Adult Hookworms are small so they are usually not seen passed in the feces. This diagnosis is made primarily by finding the distinctive egg in your pet's feces. Any pet that is anemic should have its feces checked for this parasite.

These eggs are more oval than Roundworms, and the membrane is thinner.

Treatment involves deworming with one of several products: Mebendazole(Telmintic®), Fenbendazole (Panacur ®), Pyrantel pamoate (Nemex ®, Drontal ®, or Strongid T ®). Deworming should be repeated in approximately 30 days. These products are not absorbed into the host’s body from the GI tract and can only kill the worms living within the GI tract. The point of the second deworming is to kill worms in the process of migration at the time of the first deworming, allowing them an additional month to complete their migration. There is currently no deworming strategy effective against the encysted larvae in other areas of the host’s body.

Simply killing the worms will not be sufficient to save the life of a severely affected puppy. Like any other blood loss, a transfusion may be needed to keep the puppy alive until it can replace its own lost red blood cells. An iron supplement is frequently needed as well.

Cutaneous Larva Migrans (CLM) occurs as red, inflamed lesions in the skin where the larvae of canine hookworms burrow under the skin

Contaminated soil is an important hookworm source when it comes to a human disease called Cutaneous Larva Migrans. Running barefoot through the park or beach may seem pleasant but if the soil has been contaminated with canine fecal matter, the eager infective larvae may be waiting to penetrate your skin. Hookworm infection in the skin is intensely itchy but usually treatable. Usually, the larvae will die in several weeks and the condition will disappear. In severe cases, the larvae may make their way through the skin and enter deeper tissues. This may cause lung disease and painful muscles.

Humans can also become infected by eating improperly washed vegetables which may harbor contaminated soil. Humans have been found with actual hookworm intestinal infection.

To prevent hookworm infections, we need to remember how animals become infected – either through contaminated soil or water, transport hosts, or through their mothers.

Treating the Environment: The larvae of hookworms can live several weeks in cool, moist soil, but die rapidly in freezing or hot, dry conditions. Yards and kennels should be cleaned daily. Floors in kennels and dog runs should be impervious, so they are easier to clean. All fecal material should be removed, since organic material will decrease the effectiveness of cleaning solutions. A 1% bleach solution of 1/4 cup of household bleach to a gallon of cool water should be sprayed or mopped on the area.

Any feces in yards should be picked up on a daily basis. Flaming the surface soil can kill the larvae. Gravel runs are best treated with sodium borate applied at the rate of 10 lbs/100 sq. ft. (Sodium borate will kill vegetation.)

Since mice and other rodents can serve as transport hosts, their control is important. Remember that mouse and rat poisons are poisons for dogs, cats, and other animals as well. If using one of these products, follow the manufacturer's recommendations and prevent access by your pets.

Medical Treatment and Isolation: As with any infection, animals infested with hookworms should be kept separate from other animals until their infection is cleared.

To reduce the possibility that bitches will infect their puppies, they should be placed on a special deworming program during pregnancy, prescribed by a veterinarian. They should also be treated with a dewormer at the same time as the puppies.

A fecal examination should be performed two to four times during the first year of life (more if the animal is repeatedly positive). Adults should be tested at least one to two times per year. Females should be tested before they are bred. The appropriate deworming schedule for your dog should be developed in consultation with your veterinarian, taking into account factors such as risk of exposure, immune status of family members, etc.

Many heartworm preventives treat or control infections with hookworms and are an important addition to a control program. Look at your heartworm preventive package to see if it is effective against hookworms.

Safeguarding Human Health: To prevent human infection, good hygiene is extremely important. Teach children, especially, to wash their hands after playing and before eating. Do not let children play in areas where dogs or cats may have defecated. Do not allow cats to use sandboxes or the garden as litter boxes. Persons who will have contact with the ground, especially for long periods of time, e.g., plumbers or electricians working in crawl spaces, should place an impervious material between themselves and the ground. (Hookworm infestation in man is sometimes known as 'plumber's itch.') When gardening, wear shoes and gloves.

Sunbathers, especially those lying on wet sand or ground may also be at an increased risk of becoming infected. Animals should not be allowed to defecate on beaches, and people should not walk barefoot through the sand.

Sources:

www.marvistavet.com
www.veterinarypartner.com
www.cah.com
www.lbah.com
www.peteducation.com

HOOKWORMS