Hookworm Medication for Dogs: What Vets Prescribe

Name: Hookworm Medication for Dogs: What Vets Prescribe
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Hookworms in dogs medication typically means a dewormer such as pyrantel pamoate or fenbendazole, chosen and dosed by your veterinarian based on your dog's weight, age, and health. Treatment usually involves more than one dose, plus cleanup of the environment and a follow-up fecal test to confirm the worms are gone. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Pyrantel pamoate and fenbendazole are the two dewormers most often used for hookworms in dogs in the United States [1].
Treatment almost always means repeat dosing, not a single pill, because larvae and newly maturing worms can survive the first round.
Drug-resistant hookworms are now widespread in U.S. dogs, so a follow-up fecal test after treatment is not optional [2][3].
Puppies are at the highest risk because hookworms suck blood and can cause severe anemia fast [4].
Year-round broad-spectrum parasite prevention plus picking up feces promptly lowers the chance of reinfection for your dog and your household [4].

What Hookworm Medicine Is and What Vets Use It For

Hookworms are small intestinal parasites that latch onto the lining of the small intestine with hook-like mouths. They feed on blood, detach, and reattach at new spots, leaving small bleeding ulcers behind [4]. Two species matter most in dogs. Ancylostoma caninum is the main cause of serious hookworm disease in most warm parts of the world and is considered the most pathogenic dog hookworm [1]. Uncinaria stenocephala also infects dogs and tends to cause milder disease [5].

The goal of treatment is simple to state and harder to achieve: kill the adult worms in the gut, stop the blood loss, and prevent the dog from shedding eggs that contaminate the yard, the dog park, or your own backyard.

Veterinarians reach for a small group of drugs called anthelmintics. For hookworms in dogs, the two you are most likely to see are:

Pyrantel pamoate. A common, inexpensive dewormer with activity against hookworms and roundworms. It is available in many over-the-counter puppy dewormers and in some prescription combination products.
Fenbendazole. A benzimidazole dewormer sold under several brand names, often used in a multi-day course.

Other drugs, including macrocyclic lactones such as moxidectin and milbemycin oxime, appear in broad-spectrum heartworm and parasite preventives and also have hookworm activity [1]. Your veterinarian picks the drug based on your dog's age, weight, other medications, and what is actually infecting your dog.

If you are not sure whether your dog has hookworms or roundworms, the two look similar in a stool sample to an untrained eye. This guide on how to tell if a dog has roundworms or hookworms walks through the differences owners notice at home.

How Hookworm Medicine Works

Pyrantel pamoate works by causing spastic paralysis of the parasite's muscles. The worm can no longer hold onto the intestinal wall, so it is swept out in the feces. This is why you may see worms in your dog's stool after treatment, which is expected and not a sign the medicine failed.

Fenbendazole works differently. It binds to the parasite's tubulin, a protein the worm needs to build its internal structure and absorb nutrients. Without working tubulin, the worm loses energy and dies. This is a slower kill than pyrantel, which is one reason fenbendazole is often given over several days.

Neither drug treats everything. A dewormer that handles hookworms may not touch tapeworms, whipworms, or coccidia. That is why veterinarians often run a fecal test first instead of guessing, and why broad-spectrum monthly preventives exist.

There is a growing complication. Multiple anthelmintic drug resistance, meaning resistance to more than one drug class, has been documented in A. caninum in the United States since 2019. Hookworms resistant to fenbendazole, moxidectin, and pyrantel pamoate have been confirmed, and the problem is no longer limited to Greyhounds or racing kennels [2][3]. Dogs of any breed, age, or size in every region of the continental U.S. have tested positive for resistant hookworms [2]. This does not mean dewormers stopped working. It means treatment needs to be verified, not assumed.

Hookworm Treatment for Dogs: Dosing Basics

Who decides the dose

Your veterinarian does. The dose depends on your dog's body weight, age, and overall health, plus which drug is being used and whether the dog is a puppy with a heavy worm burden. Never split a human dewormer or guess a dose from a chart you found online. Puppies in particular can be pushed into trouble by an incorrect dose.

How the medicine is given

Pyrantel pamoate is usually given by mouth as a liquid or chewable, often as a single dose that is repeated in two to three weeks. Fenbendazole is typically given once daily for three to five days. Your veterinarian will set the exact schedule for your dog, and it may differ if resistance is suspected or if your dog has other parasites at the same time.

Giving the medicine with a small amount of food reduces stomach upset and makes it easier to swallow. If your dog vomits within an hour of a dose, call your veterinarian before redosing. A second full dose on top of a partially absorbed one can cause side effects.

Missed doses

If you miss a dose of a multi-day dewormer, give it as soon as you remember, unless it is almost time for the next dose. Then resume the normal schedule. Do not double up to catch up. If you miss more than one day, call your veterinarian, because an interrupted course can leave worms alive and set up resistance.

Why retesting matters

A negative fecal test after treatment is the only way to know the worms are gone. This matters most in puppies, who can be reinfected from the mother's milk, from the environment, or from their own littermates. It also matters because resistant hookworms can survive a standard course and keep shedding eggs [2]. A follow-up fecal test, usually two to four weeks after treatment ends, catches that early.

Side Effects of Hookworm Medicine for Dogs

Most dogs tolerate dewormers well. When side effects happen, they are usually mild and short-lived.

Side effect	How common or serious	What to do
Vomiting	Common, usually mild	Withhold food for a few hours, offer water. Call your vet if it repeats or lasts more than a day.
Diarrhea	Common, usually mild	Keep water available. Call your vet if it is bloody or lasts more than 24 hours.
Drooling or lip smacking	Common with liquid pyrantel, mild	Give with food next time. This is usually a taste reaction, not poisoning.
Lethargy	Uncommon, can signal anemia in puppies	Call your veterinarian the same day, especially in a puppy.
Pale gums, weakness, collapse	Serious, emergency	Go to a veterinary emergency clinic now. This can be hookworm anemia [4][1].
Tremors, wobbling, disorientation	Uncommon, serious	Call your veterinarian or a poison control hotline right away.

Puppies with heavy hookworm loads can become anemic from the worms themselves, not the medicine. Pale gums, weakness, and black tarry stool are signs of intestinal bleeding and blood loss, and they need same-day care [1].

Who Should Not Take These Drugs and What Interacts With Them

Dewormers are not one-size-fits-all. Tell your veterinarian about every medication, supplement, and preventive your dog takes before starting treatment.

Pregnant or nursing dogs. Some dewormers are considered safe in pregnancy and others are not. Your veterinarian will choose based on the drug and the stage of pregnancy.
Very young puppies. Age and weight minimums vary by product. A puppy that is too young or too small for a given product needs a different plan.
Dogs with liver or kidney disease. Fenbendazole and other dewormers are processed by the body, and organ disease can change how a drug behaves. Your veterinarian may adjust the drug or the schedule.
Dogs on multiple parasite preventives. If your dog already takes a monthly heartworm preventive that contains moxidectin or milbemycin, adding another dewormer can overlap. Your veterinarian needs the full list.
Collies and related herding breeds. Some dewormers in the macrocyclic lactone class carry genetic sensitivity concerns in these breeds. This is a conversation for your veterinarian, not a reason to skip treatment.

If your dog has a known reaction to a dewormer, say so before the next dose. There is usually an alternative.

Overdose and When to Call for Help

Signs of overdose include vomiting that will not stop, severe diarrhea, tremors, wobbling, drooling, and unusual sleepiness. These can appear within an hour or two of a dose.

If you think your dog received too much dewormer, call your veterinarian first. If your regular clinic is closed, call a pet poison hotline or an emergency veterinary hospital. Have the product name, the strength, the amount given, and your dog's weight ready. Do not wait for symptoms to appear before calling.

If your dog has pale gums, is collapsing, or is having trouble breathing, skip the phone call and go straight to an emergency clinic.

Environmental Cleanup: The Half of Treatment Owners Forget

Killing the worms inside your dog does nothing about the eggs in your yard. Hookworm eggs and larvae live in soil, and dogs pick them up by walking on contaminated ground and grooming their paws, or by eating contaminated dirt [4].

Pick up feces immediately, every time. Hookworm eggs passed in stool need time in the soil to become infectious, so prompt removal breaks the cycle.
Treat the yard. Sunlight, dry conditions, and regular removal of waste reduce larval survival. There is no product that sterilizes a yard completely.
Cover sandboxes and play areas when not in use.
Wash bedding and clean food and water bowls regularly.
Keep your dog on year-round broad-spectrum parasite prevention, which is the single most effective way to prevent reinfection [4].

Hookworms are zoonotic. People can develop skin infections called cutaneous larval migrans after contact with contaminated soil [4][6]. Children who play in dirt and adults who garden barefoot are at the highest risk. This is one more reason cleanup is not optional. For more on how hookworms affect puppies and people, see hookworms in dogs: cutaneous larva migrans and anemia in puppies.

If your dog also has fleas or ticks, those parasites need their own plan. This overview of tick and flea medicine for dogs explains how those products differ from dewormers.

Limitations and When to Contact a Veterinarian

No article can tell you what is wrong with your dog. Individual cases need a veterinarian who can examine your dog, run a fecal test, and set a treatment plan.

Call your veterinarian the same day if:

Your dog vomits repeatedly after a dose or refuses to eat.
Your puppy seems tired, weak, or is not gaining weight.
You see black, tarry, or bloody stool.
You missed more than one dose of a multi-day dewormer.
You finished treatment but your dog still has diarrhea or looks unwell.

Go to an emergency clinic now if:

Your dog's gums are pale, white, or gray.
Your dog collapses, struggles to breathe, or cannot stand.
Your dog has tremors, seizures, or is disoriented after a dose.

Schedule a routine visit if:

You need a follow-up fecal test after treatment.
Your dog needs a year-round parasite preventive plan.
You have a new puppy who has never been dewormed or tested.
You want to switch preventives or add a new product.

Frequently Asked Questions

Can I buy hookworm medicine for my dog without a prescription?

Some pyrantel pamoate products are sold over the counter, but choosing one without a diagnosis is a gamble. You may treat the wrong parasite, use the wrong dose, or miss a resistant infection that needs a different drug. A fecal test and a veterinarian's plan cost less than a second round of failed treatment.

How long does it take to get rid of hookworms in dogs?

Most dogs stop shedding eggs within a few days to a couple of weeks after effective treatment, but the exact timing depends on the drug, the dose schedule, and whether the worms are resistant. That is why veterinarians retest instead of assume. If the follow-up fecal test is still positive, the plan changes.

Can hookworms come back after treatment?

Yes. Reinfection happens easily because eggs survive in soil for a long time, and dogs reinfect themselves by grooming contaminated paws. Year-round prevention plus prompt feces pickup is what keeps them from coming back. Treatment alone does not protect your dog from the next exposure.

Are hookworms contagious to people?

Yes. Hookworm larvae can penetrate human skin and cause cutaneous larval migrans, an itchy, creeping skin infection [4][6]. People do not get intestinal hookworm from their dog directly, but they can pick up larvae from contaminated soil. Wear shoes in areas where dogs defecate and wash hands after gardening.

Why does my veterinarian want a second fecal test after treatment?

A follow-up test is the only way to confirm the worms are gone, and drug-resistant hookworms are now common in U.S. dogs [2][3]. A negative test means you can stop worrying. A positive test means the first drug did not fully work and the plan needs to change. Skipping the retest is how resistant infections spread.

References

Hookworms in Small Animals - Digestive System. Merck Veterinary Manual.
American Association of Veterinary Parasitologists Hookworm Task Force review on best practices for diagnosis and treatment of multidrug-resistant hookworms. Journal of the American Veterinary Medical Association, 2026.
Multiple anthelmintic drug resistance in the canine hookworm Ancylostoma caninum: AAVP position paper and research needs. Veterinary parasitology, 2025.
Hookworms in dogs. Cornell University College of Veterinary Medicine.
Ancylostoma caninum and Uncinaria stenocephala hookworms: Morphological and molecular differentiation and epidemiological data in Southern Italy. Veterinary parasitology, 2025.
High Prevalence and Regional Heterogeneity of Canine Ancylostoma spp. in Ecuador: A Systematic Review and Meta-Analysis and Its Potential One Health Implications. Animals : an open access journal from MDPI, 2026.