Hookworms in Dogs

Hookworms are internal parasites found mostly in dogs, which may cause disease. There are three species of hookworm which can infect the dog. Hookworm infections tend to be more severe in younger dogs, under two months of age. They are found in warm areas with high humidity levels, such as the southern United States. These small, thin worms are typically up to a half inch long and feed on your dog’s blood and tissue fluid by attaching themselves to wall of the small intestine. In severe cases, this may lead to malnutrition and death.

Signs & Symptoms of Hookworms in Dogs

Symptoms of a hookworm infection can be seen in as few as ten days:

Bloody diarrhea, often resembling tar in severe infestations
Pale tongue, gums, and nose
Weight loss
Lethargy

After 2 to 3 weeks, your dog will start shedding hookworm eggs in his/her stool, and these eggs will hatch in about 48 hours. The newly hatched larvae will become infective within seven days.

Causes of Hookworms in Dogs

The most common hookworm species that infect dogs are:

Ancylostoma braziliense
Ancylostoma caninum (dogs only)
Uncinaria stenocephala
Ancylostoma tubaeforme (cats only)

There are many different ways that your dog can get hookworms, including:

Direct ingestion of larvae in infected soil or water
Feeding on a mother’s milk containing larvae
Migration of larvae through the placenta in dogs
Penetration of larvae through the skin, usually the foot pads
Migration of larvae through the blood, into the lungs, where the dog may cough them up and then swallow them into the intestine
Ingestion of the intermediate host, such as mice or other rodents

Diagnosis of Hookworms in Dogs

Diagnosis begins with a complete history and a physical exam. Your veterinarian will be most likely to do the following:

Fecal Floatation - This test is used to determine the presence of parasite eggs in your dog’s stool. It involves taking a small fecal sample from your dog using a lubricated fecal loop. The feces are then put in a small container with a solution that will allow most of the fecal matter to sink, and the parasite eggs to float. A slide is then made of the floating material and examined under a microscope. The slide is then scanned for hookworm eggs. Because the eggs take 2 to 3 weeks to pass in the stool, a fecal examination result may be falsely negative, and diagnosis will be based solely on clinical signs.

Treatment for Hookworms in Dogs

Your veterinarian will likely use a dewormer if your dog is positive for hookworms. Typical drugs used are pyrantel pamoate (Nemex or Strongid), fenbendazole (Panacur), febantel/praziquantel/pyrantel pamoate (Drontal Plus), and mebendazole (Temintic).

Some drugs will kill only the adult worms or cause encysted larvae to be released, so combinations of drugs (Drontal Plus), or multiple treatments. may be used (second treatment is usually 1 to 2 weeks after the first administration).

A follow-up fecal exam may be recommended by your veterinarian to ensure the infestation has been controlled.

Dogs may become carriers of hookworms after recovery from the infestation. Larvae will hide out in cysts inside your dog, and be released during times of stress or illness. This will again cause worms in the intestine and bloody diarrhea.

Prevention of Hookworms in Dogs

Hookworms can be prevented by:

Having your dog dewormed multiple times within the first three months of life, as a precaution
Having regular fecal exams for your dog every 6 to 12 months
Regular use of heartworm preventives that protect against hookworms as well
Good sanitation in kennel areas
Control of rodents (Use caution with rat poison, it is toxic to your dog!)
Testing females for the parasite prior to breeding
Subsequent litters of mothers who have passed on a fatal hookworm infection in her milk should be monitored and should be treated for the parasite aggressively. Mothers may also be treated during their pregnancy.

Hookworms can be transmitted to humans and can cause a skin disease called cutaneous larval migrans, where the larvae penetrate the skin and cause itching and lumps. If hookworms infect the human intestine, you may get a condition called eosinophilic enteritis, which causes abdominal pain.