Hookworms are a very common intestinal parasite of dogs. They get their nickname from the hook-like mouth parts (teeth) that they use to anchor themselves to the wall of the intestinal tract. Once they have attached, they feed on the blood of their host. Hookworms are very small and are difficult to see with the naked eye, but the damage and the amount of blood they consume can be massive. Large numbers of hookworms in young puppies can cause severe anemia from the blood loss and many puppies can die without a blood transfusion.
Dogs can get hookworms many different ways. Young puppies can be infected while still in their mother’s womb directly through the placenta as well as through the milk when nursing. Because of this early infection, puppies should be de-wormed when they are just 2 weeks old and repeated every 2 weeks for the first few months of their lives. Monthly de-worming is recommended as a regular prevention.
Adult dogs can become infected by walking through contaminated soil where active larvae hatched from eggs deposited in fecal matter can penetrate directly through the pads of their feet. Once the larvae enter the skin, they then migrate through the body until they reach the lungs, at which time they are coughed up and swallowed. While the hookworms are migrating through the body, many can encyst in the muscle and lay dormant for many years. These are the source of hookworms that infect puppies while in the womb. After the hookworms are swallowed, they reach the intestinal tract and latch on to the wall of the intestine and start feeding on blood. The adult worms also mate and lay thousands of eggs that are passed in the feces. The eggs hatch into larvae in moist warm environments which start the life cycle again.
Humans can also become infected if walking barefoot through contaminated areas, however, the hookworms cannot complete their life cycle, but do cause a localized dermatitis where they penetrate the skin and can cause other problems while trying to migrate through the body. Some people can have allergic reactions to the migrating worms.
Dogs can also be infected by ingesting the larvae, either by cleaning their feet or fur, or when drinking water or licking contaminated surfaces.
Because of the prevalence of hookworms in dogs, many veterinarians and the CDC (Centers of Disease Control) recommend routine de-worming with anthelmintics. Several of the newer flea and heartworm preventatives also include ingredients to remove hookworms and other parasites as well. Your puppy should be tested for hookworms as soon as your get him and follow your veterinarians recommendations for maintenance. Breeders should have the mother dog and young puppies dewormed every 2 weeks. Anthelmintics do not affect the dormant hookworms in the muscle. Studies have shown that these hookworms can release during gestation and infect the puppies for up to seven consecutive litters.
Signs of hookworm infection can include pale gums, a dark ,tarry stool, diarrhea, weight loss and failure to thrive. Older dogs can develop diarrhea or dark, tarry stools.
You can limit the amount of hookworms deposited in your yard by cleaning up the fecal material and disposing of it. Fecal waste from dogs should not be used in compost bins, but there are special compost bins to handle the waste.