Hookworms are a common intestinal parasite that affects dogs. Learn how to recognize the signs and symptoms of hookworms in dogs so you can treat it quickly and prevent it from happening.

By Sarah Mouton Dowdy
August 24, 2020
Advertisement
Westend61 / Getty

Hookworms are a common intestinal parasite in dogs—especially puppies—that can cause serious problems due to blood loss. Thankfully, monthly preventative medications and regular testing can help stop these pests from harming your pet. 

What Are Hookworms?

Hookworms are small (1-2 cm), white worms that can look similar to fishing hooks due to a slight bend at the front of their body. According to Jessica Nichols, DVM, chief veterinary officer of Spay and Neuter Kansas City in Kansas City, Mo., hookworms are particularly nasty parasites that can infect your dog. Unlike other worms that eat food and drink materials floating around the pet’s intestines, hookworms are bloodsuckers, she explains. If it sounds disgusting, it’s because it is. The parasites literally hook themselves to the walls of a dog’s intestines with their teeth, then release a substance that prevents the host animal’s blood from clotting, and begin to suck the animal’s blood. 

According to the Companion Animal Parasite Council (CAPC), an independent nonprofit led by veterinary professionals and parasite experts, Ancylostoma caninum is the most common species of canine hookworm found in the United States, though two other types are also present (Ancylostoma braziliense and Uncinaria stenocephala)

How Do Dogs Get Hookworms?

Adult hookworms that live in a dog’s intestines mate and deposit their eggs into the poop of the infected animal, Nichols explains. These eggs will later hatch, releasing baby hookworms into the soil. Dogs can then become infected by eating these baby hookworms from the soil or by eating small animals or cockroaches infected with the parasite. The baby hookworms are also able to infect dogs by burrowing into their skin.

Richard Meadows, DVM, DABVP, a professor at the University of Missouri College of Veterinary Medicine in Columbia, Mo. adds that puppies have another potential source of hookworms: their mother’s milk. Even if the mom has been dewormed and has zero incidences of the parasite in her gut, she can still transmit baby hookworms to her nursing pups, he explains. That’s because pregnancy can cause hookworms that have been dormant in muscle tissue to activate and travel to the mammary glands. 

Can People Get Hookworms?

Unfortunately, canine hookworms are zoonotic, meaning they can infect people, too. They can tunnel into the skin and cause cutaneous larva migrans, a skin disease that produces itchy, raised, snake-like lines on the skin, Nichols says. People who come into contact with the baby parasites in the soil or sand by either walking barefoot or working without gloves (as with gardening, for example) are most at risk. Though the condition is unpleasant, it’s typically easy to treat. And while canine hookworms most often affect the skin, there have been rare cases of the parasites infecting a person’s intestines

What Are the Signs of a Hookworm Infection?

The signs and symptoms of hookworm infection vary according to the dog’s age and the type of worm it’s infected with. According to CAPC, dog hookworms consume more blood than other species and thus tend to cause more serious problems—even death in puppies. Puppies who are infected with hookworms may also show the following signs and symptoms:

  • Anemia (meaning they don’t have enough red blood cells to carry the oxygen their body needs)
  • Pale gums
  • Poor hair coat
  • Failure to gain weight
  • Dehydration
  • Dark, tar-like diarrhea

Meadows explains that hookworms feeding on blood in the intestines often get knocked out of position and move to a different spot to feast. This leaves behind a bleeding wound, which can result in the dark, tar-like diarrhea that is characteristic of hookworm infections. 

Adult dogs that are infected with hookworms but are otherwise healthy may have no sign of infection. However, it’s possible for dogs to sometimes develop the following symptoms:

  • Anemia
  • Loss of appetite
  • Extreme weight loss
  • Weakness
  • Dark, tar-like diarrhea

A hookworm that has entered a pet by tunneling into its skin can leave behind itchy, irritated skin wounds—typically between the dog’s toes. 

How Are Hookworm Infections Diagnosed?

According to Nichols, a diagnosis is often made with a fecal float test. It involves using a microscope to look for hookworm eggs in a sample of the dog’s poop. According to the CAPC, combining this test with one that looks for specific hookworm antigens (substances that trigger the immune system to respond to the parasite) in the pet’s poop can improve the accuracy of the test results.

Because dogs of all ages can be infected with hookworms without showing any signs, it’s important to have your pets regularly tested by their veterinarian. Experts recommend testing puppies for worms four times within their first year of life and then testing adults twice a year. These tests are typically a part of your pet’s regular veterinary wellness exams. 

How Are Hookworms Treated?

Nichols says that dogs infected with hookworms are typically given a deworming medication to kill the parasites. Multiple doses and follow-up testing may be necessary. Meadows adds that depending on how much blood the dog has lost, it may need other treatments as well, such as a blood transfusion. 

Because hookworms are so common and deadly in puppies, the CAPC advises that puppies should be treated with dewormers as a precaution, beginning at two weeks of age. 

How Can Hookworms Be Prevented?

According to Meadows, monthly heartworm preventative medications have a misleading name. “We really sell them short by calling them that, as they don’t just protect against heartworms,” he explains. “They prevent hookworms and roundworms too, and some protect against whipworms as well.” Your veterinarian will work with you to find the best monthly parasite preventative for your dog.   

Considering how hookworms are transmitted, there are other steps you can take at home to help limit the odds of infection. These include picking up your dog’s poop as soon as possible and preventing your pup from eating any small animals that may be infected with the parasite.