Hookworms in Dogs: Symptoms and Deworming

1 How Dogs Catch Hookworms

Transmission is usually fecal-oral, through the skin, or via placenta and milk.

Fecal-oral: a female hookworm sheds hundreds of tiny eggs in the stool, contaminating the environment. Larvae hatch and stay infectious in soil for weeks or months. When a dog swallows them, most travel to the gut; some reach the trachea, are coughed up and swallowed.

Skin: walking or lying on contaminated ground lets larvae burrow in, migrate to the lungs and trachea, then to the gut to mature. Part of the life cycle passes through muscle, where larvae can lie dormant.

Milk and placenta: in a pregnant female, hormones can reactivate dormant larvae, which enter her blood and infect the fetuses through the placenta; newborns can also catch them in mother’s milk.

2 Signs of Infection

Signs relate to the gut and anemia. The worm anchors to the wall and feeds on tissue fluid and blood, releasing an anticoagulant so the attachment site keeps bleeding after the worm moves on. Pets lose blood from feeding and from the site, causing anemia. Pale gums and weakness are common; some show clear weight loss, bloody diarrhea, dull dry coat, or stunted growth. Severe cases also cough.

3 Diagnosis, Treatment, and Control

Diagnosis: a microscope exam of a fecal sample. The stool is mixed with a solution so eggs float to the top and stick to a slide; because hookworms shed many distinctive eggs daily, infection is easy to detect.

Treatment: regular internal deworming, but the drug kills only adult worms. Treat the infected dog again in about two to four weeks to kill adults that matured from larvae after the first dose. In rare severe anemia, a blood transfusion may be needed.

Zoonotic note: adult hookworms do not infect people, but larvae can burrow into human skin (often bare feet) and itch; they do not mature and die within weeks, though migrating larvae can sometimes harm eyes and internal organs.

Control: deworm puppies at two to three weeks old, clean up feces promptly and keep living areas dry, and deworm females before breeding, since pregnancy can reactivate dormant worms and infect the litter.