What are Hookworms and Why Should I Care?

Hookworms are a significant parasite of dogs and cats and have very real zoonotic implications.

What are hookworms?
Hookworms are a parasitic nematode (worm) that inhabits the intestinal tract of a host. Hookworms are named for the hook-like mouth parts with which they attach to the lining of the intestine and use to feed on the blood of the host. Hookworms can infect humans (N. americanus and A. duodonale) as well as dogs (Ancylostoma caninum, Ancylostoma braziliense, and Uncinaria stenocephala) and cats (Ancylostoma tubaeforme, Ancylostoma braziliense, Uncinaria stenocephala). They are quite small but can cause heavy infections that result in severe inflammation and blood loss; in some individuals, kittens, and puppies for example, these infections can prove fatal if not treated.

How common are hookworms?
Although more common in warmer coastal regions, hookworms are fairly common in dogs and cats throughout the U.S.  Infection rates range from 1%-35% depending on climate and lifestyle.

How does my dog get them?
Adult worms in the intestine of infected dogs reproduce and pass eggs which become infective in 1-3 weeks.  Dogs and cats can be infected by swallowing the larvae or by nursing from an infected host. Hookworms can also burrow through the skin. 

Dog OutsideWhat are the symptoms of hookworm? 
Hookworms consume blood from the lining of the intestine. An adult hookworm can consume 0.1ml per day and a heavy infection can result in significant anemia, particularly, in very small or very young animals. Blood in feces is not generally seen, but inflammation caused by these parasites can result in diarrhea.

How do I know my dog has hookworms and how do I treat it?
The worms and their eggs themselves are quite small and direct visualization should not be relied on. The best diagnostic is a microscopic examination of the stools following centrifugation. This concentrates the eggs so they can easily be seen under a microscope.

Do hookworms infect people?
Once a common disease, hookworms have all but been eradicated as an internal parasite for humans in North America. However the disease is still rather common in emerging countries. Hookworms commonly enter humans, in particular children, by burrowing through the skin. Additionally, the infective larvae can contaminate food sources and with inadequate preparation be ingested. Children can be exposed while playing in the soil or at a beach where dogs have been allowed to soil and contaminate the sand.  The infective larva burrows through the skin and begins looking for the intestinal tract of a puppy or kitten.  Not finding that new home they continue to migrate under the skin (Cutaneous Larval migrans) and produce a severe irritation.

How do I prevent hookworms?  
There are several preventive steps you can take:

  • Make sure that you only feed cooked foods.
  • Keep your pet away from damp, warm and potentially contaminated areas where they might be exposed to oral infection or infection through the skin.  
  • Deworm your own puppy or kitten as early as 2-3 weeks of age and then thereafter as directed by your veterinarian.
  • Utilize parasite preventives. (These products are available from your veterinarian and should be administered as directed)
  • Always be sure you clean up after your own dog and keep him away from the stools of other animals.

It is important to have your dog or cat tested at least yearly for intestinal parasites and to use preventive medications all year round.

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.


Beware the Bug

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Reviewed on: 
Thursday, April 17, 2014