Hookworms attached to the intestinal lining
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. The pet can be infected from contaminated dirt or can be infected by eating another animal that is infected. This could be a prey animal such as a rodent or could be an insect such as a cockroach.
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 are more bold, tunneling out of the intestine, and migrating 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 (windpipe), get coughed into the throat and swallowed. Once back in the intestine, these well-traveled worms will complete their maturation to adulthood, rejoining any friends they had that never left the intestine on a migration.
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 periodically emerging and continuing their migration.
The adult worms live by sucking blood from the intestine. Their eggs are passed by the host into the environment where a new host picks them up. The developing larvae may migrate widely through the new host’s body before settling down to complete their maturation.
It is worth repeating that the host is not always a pet. Other vertebrates such as rodents and birds can pick up hookworm larvae from the soil. If the pet eats an infected rodent or bird, the pet will become infected just the same as if the infection came directly from the soil.
(Public Domain Graphic, California Dept. of Food and Agriculture)
Now let us return to the three points we want to emphasize.
HOOKWORMS SUCK BLOOD
Hookworm infection can be looked at as a natural check in the canine population as it is frequently lethal to young puppies. A young puppy is growing and growth includes making enough new blood to serve not only its current oxygen needs but what is required for growth as well. 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 by numerous tiny vampires within. The puppy may be effectively bled to death.
Infected puppies are commonly pale, weak, and have long-standing iron deficiencies. They may or may not have diarrhea.
HOOKWORMS ARE TRANSMITTED TO NURSING PUPS
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.
(Photo Credit: Public Domain Graphic via Wikimedia Commons)
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. This means that most puppies will become infected by drinking the contaminated milk of their own mother. If this is not enough to infect the entire litter, others will become infected from the soil of their own nest which will quickly become contaminated with the stool of their infected litter mates.
It is clear why puppies are at a special risk over adult dogs when it comes to hookworms. The Companion Animal Parasite Council has recommended automatically deworming puppies for hookworms beginning at age 2 weeks in areas where hookworms are common.
CAN WE PREVENT TRANSMISSION FROM THE MOTHER?
The answer is yes but daily deworming is required through the second half of pregnancy and into the nursing period. A regular single deworming will not be effective in protecting the litter. A special protocol using Fenbendazole (Panacur®) has been found to be effective in preventing both roundworm and hookworm infection in unborn puppies.
Ask your vet about this method if you are contemplating breeding a female dog. Female dogs using Proheart6 for heartworm prevention are believed to pass fewer hookworm larvae on to their pups.
DECONTAMINATING THE ENVIRONMENT
Many people are concerned about how to decontaminate the backyard or property that has housed an infected dog. The good news is that unlike roundworms which are extremely hardy in the environment, hookworm eggs deplete their energy reserves in a few months and die. Further, hookworm eggs do not survive freezing temperatures.
If one uses bleach to clean an area, the protective coating is removed from the hookworm egg and the egg will become dehydrated and will die. Borates raked into the soil will also kill hookworm eggs but will kill grass and vegetation as well.
Most heartworm preventives will also prevent hookworm infection. To view a chart showing which products work against parasites beyond heartworm click here.
There are two species of hookworms in cats: Ancylostoma tubaeforme and Ancylostoma braziliense, the former being the most aggressive blood sucker . The story is pretty much the same for cats with a few exceptions:
Page last updated: 9/19/2014