Hookworm

Hookworm Infection in Dogs

What are hookworms?

Hookworms (Ancylostoma caninum, Ancylostoma braziliense) are parasites that get their name from the hook-like mouthparts they use to attach to the intestinal wall. They are only about 1/8" (3 mm) long and so small that it is very difficult to see them with the naked eye. Despite their small size, they ingest large amounts of blood from the tiny vessels in the intestinal wall. A large number of hookworms can cause anemia. This problem is most common in puppies, but can occur in adult dogs. 

How did my dog get hookworms?

Dogs may become infected with hookworms by four routes:

1.    Orally

2.    Through the skin

3.    Through the mother's placenta before birth

4.    Through the mother's milk

A dog may become infected when it swallows hookworm larvae. The larvae may also penetrate the skin and migrate to the intestine where they mature and complete its life cycle. If a pregnant dog has hookworms, the pregnancy may reactivate larvae. These larvae will enter the female's bloodstream and infect the puppies in the womb. Finally, puppies may be infected through the mother's milk. This is considered to be an important route of infection for puppies.

What kinds of problems do hookworms cause?

The most significant problems appear related to intestinal distress and anemia. Blood loss results from the parasites ingesting blood from intestinal capillaries. Pale gums, diarrhea, or weakness are common signs of anemia. Some dogs experience significant weight loss, bloody diarrhea, or failure to grow properly with hookworm infection.

Skin irritation and itching, especially of the paws, can be signs of a heavily infested environment. The larvae burrow into the skin and cause itching and discomfort. 

How is hookworm infection diagnosed?

Hookworms are diagnosed with a microscopic examination of a stool sample. Since there are many eggs produced daily, they are easily detected. One adult female hookworm may produce as many as 20,000 eggs a day!

In puppies, large numbers of worms usually must be present before eggs are shed into the stool. For this reason, fecal examination may be less reliable in very young puppies than in adult dogs.

How are the hookworms treated?

There are several effective drugs to eliminate hookworms. They are given by injection or orally and have few, if any, side-effects. However, these drugs only kill the adult hookworms. Therefore, it is necessary to treat again in about 2-4 weeks to kill any newly formed adult worms that were larvae at the time of the first treatment.

A blood transfusion may be necessary in dogs with severe anemia.

Since the dog's environment can be infested with hookworm eggs and larvae, it may be necessary to treat with chemicals to remove them from your yard. We can offer recommendations for grass-friendly products. 

Are canine hookworms infectious to people?

Adult hookworms do not infect humans; however, the larvae can burrow into human skin. This causes itching, commonly called “ground itch”, but the worms do not mature into adults. Direct contact of human skin to moist, hookworm infested soil is required. Fortunately, this does not occur often if normal hygiene practices are observed.

In rare instances, the canine hookworm will penetrate into deeper tissues and partially mature in the human intestine. A few reports of hookworm enterocolitis (small and large intestinal inflammation) have occurred in the recent past.

What can be done to control hookworm infection in dogs and to prevent human infection?

All pups should be dewormed with a veterinary-approved product at two to three weeks of age.

Prompt deworming should be given when parasites are detected; periodic deworming may be appropriate for pets at high risk for infection.

Prompt disposal of dog feces should occur, especially in yards, playgrounds, and public parks.

Strict hygiene is important, especially for children. Do not allow children to play in potentially contaminated environments. Frequent hand washing and bathing are essential in preventing human infections.

Nursing females should be dewormed with their pups. Nursing may reactivate hookworm infection in the female.

Most heartworm prevention products contain a drug that will prevent hookworm infections. However, these products will not kill the adult hookworms, so dogs must be treated for adult hookworms.


Hookworm Infection in Cats

Hookworms are intestinal parasites of the cat and dog. Their name is derived from the hook-like mouthparts they use to anchor to the lining of the intestinal wall. They are only about 1/8" (two to three mm) long and so small in diameter that they are barely visible to the naked eye.

The scientific names for the most common feline hookworms are Ancylostoma tubaeforme and Ancylostoma braziliense. Occasionally, cats will also become infected with the dog hookworm, Ancylostoma caninum.

In general, cats tend to harbor relatively few hookworms when compared to the large numbers found in dogs. Also, the feline hookworms tend to be less aggressive bloodsuckers than the canine species.

Are certain cats more likely to get hookworms?

Hookworms are more common in warm, moist environments. Conditions of overcrowding and poor sanitation contribute to re-infection.

What are the clinical signs of feline hookworm infection?

Feline hookworms tend to “graze” along the lining of the small intestine and are considered “tissue feeders.”  When they do suck blood, an anti-coagulant substance is injected at the feeding site. Therefore, the cat can suffer blood loss from the hookworm’s feeding as well as continued bleeding into the bowel. The blood-loss anemia attributed to hookworms is a more significant problem in kittens than adult cats.

Evidence of hookworm infection includes anemia, the presence of digested blood in the stool, a poor haircoat, and weight loss.

How do cats get hookworms?

Adult hookworms pass hundreds of microscopic eggs in the cat's stool. The eggs are not visible to the naked eye. Larvae or immature hookworms will hatch from the eggs and persist in the soil for weeks or months. When a cat inadvertently swallows larvae, often by grooming its feet, a hookworm infection is established. The larvae may also burrow through the cat's skin and migrate to the intestine, where they may mature and complete their life cycle.

In dogs, prenatal infection (infection prior to birth) may be a significant problem. Puppies may become infected by the placental blood flow and then later through the mother’s milk. Prenatal infection has not been demonstrated to occur in kittens.

How is hookworm infection diagnosed?

To diagnose hookworm infection, a small amount of the cat’s stool is mixed into a special solution, causing the hookworm eggs to float to the top, and adhere to a glass slide that has been placed on the top of the solution. The eggs are easily identified under a microscope because of their unique appearance. Since the eggs are produced on a daily basis, hookworm infection is usually fairly easy to diagnose. The number of eggs does not necessarily correlate with the number of worms present. In fact, the number of eggs passed can be greater with light infections of smaller numbers of hookworms.

How is feline hookworm infection treated?

Fortunately, treatment is safe, simple, and relatively inexpensive. After administration of the deworming medication called an anthelmintic, the adult hookworms are killed. At least two treatments are needed typically performed at two to three week intervals. Ideally, kittens are treated for worms during their kitten vaccination series.

In rare cases, kittens or debilitated cats might require a blood transfusion because of severe anemia.

Will my cat recover?

With appropriate diagnosis and treatment, the prognosis is good for full recovery from hookworm infection.

Can hookworms be prevented?

Prevention of hookworm infection should include the following measures:

All newborn kittens should be dewormed by two to three weeks of age. To effectively break the life cycle of the most common intestinal parasites, kittens should be dewormed on the schedule recommended by the veterinarian.

Prompt treatment for worms should be given when any parasites are detected; periodic deworming may be appropriate for cats at high risk for re-infection.

Use of a monthly heartworm and flea preventive that also prevents hookworm infection  is recommended.

Appropriate disposal of cat and dog feces, especially away from yards and playgrounds, is important.

Strict hygiene is especially important for children. Do not allow children to play in potentially contaminated environments. Be mindful of the risk posed by public parks and non-covered sandboxes. Sandboxes that have fitted covers are popular and help to prevent infection of children with intestinal parasites.

Control of rodents is important since they may play a role in transmission of hookworms to cats.

Stool should be removed from litterboxes daily, if possible. Always wash hands after handling litterbox material.

Can hookworms be transmitted to humans?

Feline hookworms do not infect humans internally. However, the tiny larvae can burrow into human skin, causing a disease called cutaneous larval migrans. Also known as “ground itch”, this skin infection does not lead to maturation of the larvae. Because contact of human skin with moist, larvae-infected soil is required, infection rarely occurs when good hygiene is practiced.

 



  This client information sheet is based on material written by Ernest Ward, DVM

© Copyright 2005 Lifelearn Inc. Used with permission under license. January 13, 2017




 This client information sheet is based on material written by Ernest Ward, DVM.

© Copyright 2005 Lifelearn Inc. Used with permission under license. January 13, 2017

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