By Dr. Karen Burgess

What exactly is a hookworm?
Hookworm is a parasite or worm found in the small intestine. The adult hookworm is only 1/8” in length but has six teeth and a voracious appetite for the blood it ingests after “hooking” onto the intestinal wall. There are several different species of hookworms that infect dogs, cats, and humans.

What are the signs of hookworm infection?
Animals that test positive for hookworm may have no symptoms, be critically ill, anemic, or present with profuse diarrhea. Anemia from blood loss is typically the most dangerous aspect of hookworm infection for puppies and kittens. For animals infected via the skin itching may be the primary symptom. In some cases the hookworm migrates through the lung before ending up in the small intestine, thus leading to a cough or respiratory signs.

How do dogs and cats get hookworm?
Hookworm disease can be transmitted in several different ways. Eggs are shed in fecal matter and become infective larva. When another dog or cat swallows these eggs they travel to the intestine and after several stages of development attach to the intestinal wall causing disease. In dogs, hookworms can be transmitted from mother to baby via the placenta during pregnancy or nursing after delivery. The lifecycle of the hookworm allows it to “hibernate” in the adult female’s muscle tissue. Pregnancy hormones then awaken the dormant larva releasing them into the bloodstream to be passed on to the fetus or baby. This is why it is very common for newborns to have parasites in spite of the mother having been dewormed. Hookworm eggs that have matured into larva in the stool can also infect animals or people by penetrating the skin. Finally, an animal may ingest another animal (ex. cockroaches, rodents, birds) that have ingested hookworm larva thus becoming infected themselves.

How is hookworm diagnosed?
A microscopic examination of fecal matter will typically demonstrate hookworm eggs as the adult female can produce 20,000 eggs daily. In the very young however life-threatening disease from the adult hookworm may develop before eggs are seen on a fecal examination. For this reason multiple deworming treatments are recommended for puppies and kittens regardless of fecal results.

What is the treatment for hookworm?
Treatment for the adult hookworm involves an oral or injectable dewormer while also addressing any clinical disease. Monthly heartworm preventative pills also typically contain dewormer for hookworms. Hookworm larva that have not yet matured or arrived in the intestine will not be treated by standard dewormers. This requires repeated treatments as they mature to adults and become susceptible to drugs.

How can hookworm be prevented?
Hookworm is found frequently in the environment making prompt removal of fecal matter essential to control. General good hygiene/handwashing and wearing shoes outside can prevent human exposure. Hookworm eggs do not survive freezing temperatures or hot dry situations. They are typically are short-lived in the environment dying on their own after several months. Cleaning hard surfaces with dilute bleach (one cup per gallon of water) is recommended. Avoid taking an infected pet to swim or communal dog areas in an attempt to minimize exposure to others. Monthly treatment with heartworm preventative as early as possible along with frequent dewormings of puppies and their mothers helps further prevent disease.

Can humans contract hookworm?
Humans are not infected by adult hookworms however hookworm larva can penetrate skin causing an itchy lesion and a condition called cutaneous larval migrans. This normally occurs with extended (5-10 minutes) contact between skin and hookworm infested soil. Sunbathers may be at greater risk from laying on contaminated soil. Less commonly humans can develop hookworms in their intestine typically after ingesting produce that has not been properly washed.