Hookworms in Dog and Cats
Hookworms are common intestinal parasites of dogs and cats, and certain hookworm species can also infect people. Hookworms are small parasites, usually only 1-2 cm long, that attach with teeth to the small intestinal wall. They are not often seen in the fecal material due to their small size and good attachment. Once attached, the hookworms suck blood from the host which can cause severe anemia in some cases. Continue reading to learn more about hookworms, how they can infect pets and people, how to test for them, and how to treat the infection once it’s present.
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What are hookworms?
The most common hookworm in dogs is Ancylostoma caninum, which infects dogs and causes anemia since this species sucks the most blood from its host.
The most common hookworm in cats is Ancylostoma tubaeforme, which only infects cats and causes anemia since it sucks the most blood from the host. Cats can also get infected with A. braziliense, which can infect dogs and people, but does not often cause disease in cats.
Cats and dogs can also become infected with Uncinaria stenocephala in the northern parts of the USA.
Hookworms can live in the small intestines for 4 to 24 months!! The female worms can produce 600 to 6,000 eggs per day. The eggs are then passed out of the host in the feces and into the environment. The eggs hatch into larvae and go through a few growth stages over 2 to 9 days when they reach their infective stage.
How can my pet get infected with hookworms?
Hookworms can cause infections in a variety of ways. The hookworm eggs are passed in the feces and hatch in the environment. The hookworms complete 3 developmental stages outside until they reach the 3rd stage, which is also the infectious stage. If your dog or cat is eating grass, leaves, or dirt outside, they can ingest the hookworm larvae which can pass into the small intestines and attach. The larvae can also penetrate through the soft tissue in the mouth or GI tract, enter the bloodstream, and reach the lungs.
Once the hookworm larvae are in the lungs, they move into the trachea where they cause irritation. The dog or cat coughs up the larvae and swallows them, where they enter the small intestines and attach to the tissue there. Once attached, the hookworms mature into adults, mate, and lay eggs.
Hookworm larvae can also be ingested by other temporary hosts, such as the cockroach. If your cat or dog eats a roach that is infected, the hookworms will attach to the small intestines and begin to mature.
The hookworm species A. braziliense is often acquired by skin penetration. The 3rd stage larvae of the hookworms will burrow into the skin of the paws or other areas, causing itching and skin inflammation. The larvae will then move through the body and enter the lungs where they are coughed up and swallowed and then attach to the small intestines and complete their life cycle.
In dogs, hookworms can also be transmitted to nursing puppies via the colostrum. This is called transmammary transmission and is a very common route of infection in puppies.
How can I get infected with hookworms?
Humans can get infected with hookworms, mainly A. braziliense. Once the hookworm eggs are shed in dog and cat feces, the larvae hatch and develop. They can then penetrate human skin, typically the feet and limbs. In the USA, most infections are reported in the Southeast and Gulf Coast regions and mainly in children that have been playing in sandboxes, parks, or the beach. This causes a condition called Cutaneous Larval Migrans.
What symptoms might I see if my pet has a hookworm infection?
Many adult pets do not show symptoms of hookworm infection. Infections tend to be more severe in puppies and kittens.
Clinical symptoms can include:
- Black stools
- Pneumonia in severe cases
- Pale gums
- Poor weight gain or weight loss
- Dermatitis if the hookworms penetrate into the paws
How can my vet test for hookworms in my pets?
- The most common test is a fecal floatation exam where the eggs can be detected in the feces.
- A fecal PCR test can also be run to differentiate what type of hookworm infection is present.
- Blood work may show regenerative anemia and an increase in one of the white blood cells, the eosinophils, which often rise with allergies and parasitic infections.
How can my pet be treated if they have hookworms?
There is a variety of deworming medications that can treat hookworms, but it’s very important to know that most of these medications only kill the hookworms that are in the intestinal tract when the medication is given. This is why the deworming medication needs to be repeated in about 2-3 weeks so the hookworm larvae that are moving through other parts of the body have time to reach the intestines and be killed by the second dose of medication.
If your puppy or kitten is anemic, they may need a blood transfusion, iron supplement, and GI supportive medications to help the ulcers heal that are left when the hookworms detach.
Puppies and kittens are recommended to be dewormed with a deworming medication for hookworms and roundworms every 2 weeks for 2 months after birth.
Your vet will typically recommend rechecking a fecal sample 1-2 weeks after the last dose of deworming medication to see if the infection has resolved.
How can I prevent my pet from getting infected with hookworms?
Hookworms are everywhere, so there is no way to prevent exposure completely.
Picking up the fecal material immediately can help limit environmental contamination. The Ancylostoma species can be killed by hard freezes.
Cleaning hard surfaces with 1% bleach can kill hookworms.
Hookworm larvae can be killed with desiccants, such as sodium borate, but this will also kill grass and vegetation, so it’s mainly used in gravel dog runs.
Most heartworm preventative medications have an ingredient in them that can kill hookworms. However, since these doses are typically given once a month, it’s still possible for your pet to become infected with hookworms.
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