Worms are a common problem in dogs, but choosing the right dewormer can be confusing. Walk down the pet-care aisle and you’ll find products containing ingredients such as pyrantel pamoate, praziquantel and fenbendazole. They may all be labeled as dewormers, but they don’t necessarily treat the same parasites.

The key to choosing an appropriate dog dewormer is understanding which type of worm you’re trying to treat and which active ingredients are effective against it.

Here’s a simple guide to four of the most common intestinal worms in dogs: roundworms, hookworms, tapeworms and whipworms.

Quick Guide: Which Dewormer Kills Which Worms?

Type of Worm	Common Active Ingredients Used for Treatment
Roundworms	Pyrantel pamoate, fenbendazole
Hookworms	Pyrantel pamoate, fenbendazole
Tapeworms	Praziquantel
Whipworms	Fenbendazole; certain prescription preventives may also treat/control whipworms

Always check the product label carefully. A dewormer that treats one type of intestinal worm may have little or no effect on another.

Roundworms in Dogs

Roundworms are among the most common intestinal parasites found in dogs, particularly puppies.

Adult roundworms are relatively large and may sometimes be visible in a dog’s stool or vomit. They are often described as looking like spaghetti or thin noodles.

Dogs can become infected by swallowing roundworm eggs from contaminated soil, feces or other materials. Puppies can also acquire certain roundworms from their mother.

Signs of roundworms may include:

• Visible spaghetti-like worms
• Pot-bellied appearance, particularly in puppies
• Diarrhea
• Vomiting
• Poor growth
• Dull coat
• Weight loss

Some infected dogs show few or no obvious symptoms.

What kills roundworms in dogs?

Two commonly used active ingredients are:

Pyrantel pamoate – Commonly found in dog and puppy dewormers and used against certain roundworms and hookworms.

Fenbendazole – A broad-spectrum deworming medication used against several intestinal parasites, including certain roundworms, hookworms and whipworms.

Treatment may need to be repeated according to the product label or your veterinarian’s instructions because deworming does not necessarily eliminate every developmental stage of the parasite at once.

Hookworms in Dogs

Hookworms are small intestinal parasites that attach to the lining of a dog’s intestine and feed on blood.

Unlike roundworms, owners usually won’t see adult hookworms in their dog’s stool with the naked eye. A fecal examination performed by a veterinarian is a much more reliable way to detect an infection.

Hookworms can be especially dangerous for puppies because blood loss may lead to severe anemia.

Signs of hookworms may include:

• Diarrhea
• Dark or tarry stool
• Pale gums
• Weakness
• Weight loss
• Poor growth in puppies

What kills hookworms in dogs?

Common active ingredients include:

Pyrantel pamoate – Effective against certain species of hookworms as well as roundworms.

Fenbendazole – Used to treat several intestinal parasites, including certain hookworms.

Because hookworms can cause significant blood loss, puppies or dogs showing weakness, pale gums, bloody or very dark stool should receive veterinary attention promptly.

Tapeworms in Dogs

Tapeworms look very different from roundworms.

Rather than seeing an entire worm, owners often notice small individual tapeworm segments around the dog’s rear, in bedding or in fresh stool.

These segments are commonly described as looking like grains of rice or cucumber seeds.

One of the most common tapeworms in dogs, Dipylidium caninum, is closely associated with fleas. Dogs become infected when they swallow an infected flea while grooming or biting at itchy skin.

Dogs can also acquire other species of tapeworms by eating infected animals or raw tissues.

Signs of tapeworms may include:

• Rice-like segments near the anus or in stool
• Scooting or licking around the rear
• Mild digestive upset
• Weight loss with heavier infections

Many dogs with tapeworms otherwise appear healthy.

What kills tapeworms in dogs?

The key ingredient to look for is:

Praziquantel – A commonly used medication for treating several species of tapeworms in dogs.

This distinction is important because many basic dog dewormers containing only pyrantel are intended for roundworms and hookworms and will not treat tapeworms.

Don’t forget the fleas

If fleas caused the tapeworm infection, treating the worms without controlling the fleas can lead to reinfection.

Effective treatment therefore often requires addressing both the tapeworm and the flea problem.

Whipworms in Dogs

Whipworms live in the large intestine and cecum. They’re considerably more difficult for owners to identify because the worms themselves are rarely seen in stool.

Dogs become infected by swallowing whipworm eggs from a contaminated environment. Those eggs can persist in the environment for long periods, making reinfection a concern.

Signs of whipworms may include:

• Diarrhea
• Mucus in the stool
• Blood in the stool
• Weight loss
• Dehydration
• Straining to defecate

Because these symptoms can also occur with many other health problems, whipworms shouldn’t be diagnosed based on symptoms alone.

What kills whipworms in dogs?

Fenbendazole is commonly used to treat whipworm infections.

Certain prescription parasite preventives can also treat or control whipworms.

Whipworm treatment may require repeated treatment because of the parasite’s life cycle and the possibility of continued exposure to eggs in the environment. Follow your veterinarian’s recommendations or the directions on the approved product being used.

Why “Broad-Spectrum” Doesn’t Always Mean Every Worm

One of the easiest mistakes to make when buying a dog dewormer is assuming that “broad-spectrum” means the product kills every type of worm.

It doesn’t necessarily.

For example, a product containing pyrantel pamoate may treat roundworms and hookworms but not tapeworms or whipworms.

A combination product containing pyrantel and praziquantel may cover roundworms, hookworms and tapeworms but still may not cover whipworms.

That’s why the active ingredients and the parasites listed on the product label matter more than the word “dewormer” on the front of the package.

Can You Tell What Kind of Worm a Dog Has by Looking at Its Stool?

Sometimes you can get a clue, but not always.

Spaghetti-like worms may indicate roundworms.

Rice-like segments may indicate tapeworms.

Hookworms and whipworms generally aren’t easily identified by simply looking at a dog’s stool.

Even when no worms are visible, a dog can still have intestinal parasites. A veterinarian can perform a fecal test to look for evidence of parasites that can’t be readily seen with the naked eye.

How Often Should You Deworm a Dog?

There isn’t one deworming schedule that’s appropriate for every dog.

Puppies generally require more frequent parasite treatment because intestinal worms are especially common early in life. Adult dogs may receive parasite control through routine preventives and periodic fecal testing.

A dog’s appropriate parasite-control plan can depend on factors including:

• Age
• Lifestyle
• Geographic location
• Exposure to other animals
• Hunting or scavenging
• Flea exposure
• Previous parasite infections
• Preventive medications already being used

Your veterinarian can recommend a testing and parasite-prevention schedule based on your dog’s individual risk.

Don’t Guess When Your Dog Is Sick

Over-the-counter dewormers can be useful when used appropriately, but diarrhea, vomiting, weight loss and blood in the stool aren’t specific to worms.

If your dog is sick, symptoms are severe or persistent, you’re unsure which parasite you’re dealing with, or treatment doesn’t resolve the problem, contact your veterinarian.

Puppies deserve particular attention because heavy parasite burdens and conditions such as hookworm-related anemia can become serious quickly.

Choosing the Right Dog Dewormer

Before selecting a dewormer, check the label for two things:

1. Which parasites does it treat?

Look specifically for roundworms, hookworms, tapeworms or whipworms rather than assuming all worms are covered.

2. What are the active ingredients?

Remember these common associations:

• Pyrantel pamoate: Roundworms + hookworms
• Praziquantel: Tapeworms
• Fenbendazole: Certain roundworms + hookworms + whipworms

Combination products may provide coverage against several types of worms.

Most importantly, follow the product’s age, weight, dosing and treatment instructions exactly. Don’t combine dewormers unless the combination is specifically labeled for use together or your veterinarian has instructed you to do so.

Make Deworming Easier with GREENIES Pill Pockets

Finding the right dewormer is only half the battle. The next challenge may be getting your dog to actually take it.

Many dog dewormers are available as tablets or other oral medications, and some dogs aren’t exactly cooperative when a pill suddenly appears at treat time. If your dog spits pills out or carefully eats around medication hidden in food, GREENIES Pill Pockets can make giving oral medication easier.

Pill Pockets are soft treats with a built-in pouch designed to hold a tablet or capsule. Simply place the medication inside, pinch the treat closed around it and give it to your dog as a treat.

They’re available in different sizes for smaller tablets and larger capsules, making them a convenient addition to your dog’s deworming routine.

UPCO Tip: If you’re purchasing an oral dog dewormer, consider picking up a package of GREENIES Pill Pockets at the same time. Having something ready to hide the medication in can make treatment much easier for both you and your dog.

Always follow the dewormer’s dosing instructions. If the medication’s directions require it to be given in a particular way, follow the product label or your veterinarian’s instructions.

The Bottom Line

Not all dog worms are the same, and neither are dog dewormers.

If you remember only a few things, remember this: roundworms can resemble spaghetti, tapeworm segments can resemble rice, and hookworms and whipworms usually aren’t something you’ll identify just by looking at your dog’s stool.

Then look at the active ingredients.

Pyrantel pamoate is commonly used for roundworms and hookworms. Praziquantel is the ingredient commonly used for tapeworms. Fenbendazole provides broader coverage that includes certain roundworms, hookworms and whipworms.

When you’re uncertain about the parasite involved, a fecal test and guidance from your veterinarian are the safest ways to determine what your dog needs.

This article is intended for general educational purposes and is not a substitute for veterinary diagnosis or treatment. Always follow product labeling and consult your veterinarian if you have concerns about your dog’s health.