Drug-Resistant Canine Hookworms: Superworms not Responding to Treatment?

Drug-resistant infections are one of the veterinarians’ and dog parents’ worst nightmares.

Hookworms worms are true blood-suckers. These common, tiny small intestinal parasites anchor themselves in the intestinal lining, feeding on blood. Despite their size, hookworms can ingest a surprisingly large amount of blood.

Consequently, hookworm infestation can lead to anemia as well as inflammation of the intestine.

Drug-Resistant Canine Hookworms: Superworms not Responding to Treatment?

How does a dog contract hookworms?

Puppies typically contract the infection directly from their mother, the milk, or the placenta.

Adult dogs can get hookworms by environmental exposure. Hookworm larvae can make it into your dog system via:

  • eating contaminated feces or soil
  • licking their feed after walking in the contaminated environment
  • lying or walking on contaminated soil
  • eating an infected animal

Each hookworm female produces hundreds of eggs that then make their way out in the infected dog’s stool. Then eggs hatch, and the larvae remain in the soil for a long time. Hookworms thrive in warm, moist environments.

Eventually, the larvae make their way into your dog’s intestines, where they mature into worms.

Further reading: Hookworm Infection in Dogs

An adult dog can contract hookworms by ingestion or through the skin.

Symptoms of hookworm infection


Puppies are most likely to suffer severe effects of severe infections, and the symptoms include:

  • blood in the stool
  • pale gums
  • weakness
  • lethargy
  • stunted growth
  • dull and dry coat
  • looking unwell
  • couthing

Hookworm infection can be fatal in puppies.

Adult dogs

  • loss of appetite
  • blood in the stool
  • weight loss
  • weakness
  • lethargy

The two issues that arise from hookworm infections are intestinal distress and, worse, anemia that can become severe.

Drug-Resistant Canine Hookworms: Superworms not Responding to Treatment?
Hookworm; `1/8 inch

Hookworm treatment

The standard treatment of hookworm infection in puppies and adult dogs are various deworming products—anthelmintics. Dogs with a severe infestation also need supportive treatment such as:

  • IV fluids
  • iron supplementation
  • high protein diet
  • blood transfusions

The caveat with deformers is that they only kill adult worms,s and infection requires follow-up treatment. For adult dogs, most heartworm preventives also target hookworms.

The classes of dewormers for dogs include:

  • benzimidazoles
  • macrocyclic lactones
  • tetrahydropyrimidines

The emergence of drug-resistant hookworms

According to research at the University of Georgia, hookworms are becoming resistant to dewormers.

There is a rise of multi-antihelmintic drug-resistant (MADR) hookworms—hookworms resistant to two or more classes of dewormers. The first report emerged in 2019, but new research is ever more problematic.

A recent analysis of Greyhounds revealed that four out of five of the tested Greyhounds were positive for hookworms. These dogs are susceptible to infection and dewormed regularly. Further, The rest of the dogs could have hookworms because of false-negative results.

The dogs remained positive even after a deworming treatment.

At this time, it is not clear whether other breeds have the same problem. However, further testing suggests that hookworm resistance to benzimidazoles is common. Further, the worms can be resistant to different dewormers as well.

Hookworm mutations

It is, unfortunately, not uncommon that places with high infection rates offer opportunities for mutations. Moreover, if that pairs with frequent deworming, only the resistant worms survive and pass the on the “successful” mutation. Eventually, only the resistant worms dominate.

And without follow-up post-treatment testing, nobody is any wiser until the resistant infection becomes severe.

Therefore, any place where dogs exercise or hang out is at risk of a potential drug-resistant hookworm outbreak. Unfortunately, that includes dog parks as well.

Given the variety of ways a dog can contract the infection, it can spread quickly. And with the resistant strains, treatment is no longer straightforward until new drugs emerge.

Potential solution

Another recent study suggests that the resistant canine hookworms seem to be vulnerable to a cat dewormer—emodepside.

Source article:
Dog Parasite is Developing Resistance to Treatments

Related articles:
A Primer On Intestinal Worms: Types, Symptoms, and Diagnosis of Intestinal Worms in Dogs

Categories: ConditionsDog health advocacyHookwormIntestinal parasitesParasites

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Jana Rade

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience.

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