What’s The Best Dewormer For Dogs? Your In-Depth Guide

No one wants to hear the dreaded sentence, “Your dog has worms,” and yet, every day, thousands of dog owners throughout the world are told just that. So what are these worms and what are the treatments for them?

What Sort Of Worms Can Dogs Get?

When someone says that their dog has worms this actually means that the dog has internal parasites. The following is a list of the most common internal parasites that are diagnosed in our canine companions.

Intestinal Parasites


Roundworms are a type of intestinal parasite. There are two types of roundworms that are commonly found in dogs, the toxocara canis and the toxascaris leonine.

How Do Dogs Get Roundworms?

There are several ways that dogs can contract roundworms.

1. From Their Mother: When an adult dog has had roundworms, even if the infestation has been cleared, dormant larvae can remain in their tissue. If a female dog becomes pregnant, these larvae can be passed to the fetuses or passed to puppies while they nurse.

2. Ingesting Infected Animals: Even though roundworms may not reach maturity in other animals, the eggs can still exist in a dormant mode. If a dog eats an insect, worm, bird, mouse, or another animal that has roundworm eggs, the eggs will activate and begin the life-cycle process.

3. Environmental Exposure: If your dog eats soil, plants, or feces that contain roundworm eggs these eggs will begin to mature in their GI tract.

Roundworms can cause serious malnutrition if left untreated, especially in puppies.

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Ancylostoma caninum or Ancylostoma braziliense are intestinal worms that literally hook into the sides of the intestines with a hook-shaped mouth. Once attached, they feed on the blood of the dog.

How Do Dogs Get Hookworms?

There are several ways that dogs can get hookworms:

1. Ingesting The Hookworms: If a dog eats soil or feces with hookworms then those worms will implant themselves in the intestines.

2. Through The Skin: Hookworms can literally burrow into a dog’s skin if they spend time lying on soil that’s infested with hookworms.

3. From Their Mother: If a pregnant dog has hookworms they can pass the worms to their puppies both in utero and through nursing.

Without treatment, hookworms can cause severe anemia in dogs.


Another type of intestinal parasite, the tapeworm is flat and frequently breaks off into smaller segments that can look like rice in a dog’s poop.

How Do Dog’s Get Tapeworms?

The most common way for a dog to get a tapeworm is to eat a flea that’s infected with tapeworm larvae. Even if your dog is well treated with flea and tick preventatives, this doesn’t stop fleas from trying to jump onto a new host, like your dog.

Additionally, fleas are often in the environment and could be ingested if your dog eats soil or plants while outside.


Whipworms, also known as trichuris vulpis, are another common intestinal worm found in dogs. Despite being one of the smallest intestinal parasites, whipworms can cause dogs to become very ill.

How Do Dogs Get Whipworms?

Whipworms lay their eggs inside of their host and those eggs are distributed throughout the surrounding environment through feces. If a dog ingests any soil or feces with the eggs, they too will have whipworms.

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What Are The Best Dewormers For Intestinal Parasites?

Symptoms that could indicate your dog has intestinal parasites may include vomiting, diarrhea, and lethargy. Many dogs never show symptoms at all, however, pet parents notice worm segments in their dog’s feces.

While you should always take your dog’s health seriously and should consult a veterinarian if your dog’s symptoms worsen, there are over the counter dewormers that can treat your pet. The following are some of the top-rated dewormers on the market:

1. Bayer Quad: This 4-in-1 dewormer will tackle tapeworms, whipworms, roundworms, and hookworms.

2. Safe-guard 4 Dewormer: This is another 4-in-1 dewormer that can be given to puppies 6 weeks or older.

3. Nemex-2: This dewormer is commonly used to control roundworms and hookworms in dogs, especially puppies that should be dewormed on a regular basis.

4. PetArmor Sure Shot: This dewormer also treats roundworms and hookworms. It makes the list, however, because it is safe to use in puppies as young as 2 weeks.

Keep in mind that you need to purchase the dosage that’s appropriate for your pet’s weight and will likely need to treat them more than once. Be sure to read all of the instructions on the package and seek medical attention if your dog’s health worsens.

How Are Dogs Treated For Giardia?

Although Giardia is technically an intestinal parasite, it cannot be treated with the aforementioned dewormers.

What Is Giardia

Giardia are actually just single-cell parasites that reside in the intestines and inhibits a body’s ability to absorb nutrients.

How Do Dogs Get Giardia?

Like the majority of internal parasites, giardia are shed in the feces of the carrying host. The most common way for a dog to get giardia is to drink from a water source or eat a plant that has come into contact with feces.

A serious giardia infestation can cause malnutrition, weight loss, diarrhea, vomiting, and lethargy. The treatment is typically an antibiotic called Metronidazole that must be prescribed by a veterinarian after careful testing.

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Heartworms: Easily Preventable, Difficult To Treat

Each year, thousands of dogs die from the damage caused by heartworms.


Heartworm is arguably the most dangerous internal parasite that can be found in dogs. This parasite, called dirofilaria immitis, travels through the bloodstream to become embedded in the heart where it will continue to grow into adulthood. Worms can reach 4 – 12 inches in length and can cause serious hearth and lung damage if left untreated.

How Do Dogs Get Heartworm?

Dogs do not get heartworm from contact with other dogs. Heartworm larvae are transmitted to dogs through a mosquito. When a mosquito bites an infected animal, they become infested with the larvae and transmit the larvae to another host the next time they feed.

Dogs who have heartworms growing in their cardiac system will frequently develop a cough and may begin to show signs of lethargy during and after exercise.

How Is Heartworm Treated?

Once your dog has been diagnosed with heartworm they will need to undergo treatment. Depending on the severity of the infestation, treatment may include hospitalization, fluids, antibiotics, and injections of a drug called melarsomine.

How Can I Prevent Heartworm?

Today there are many heartworm preventatives, which are essentially a type of dewormer, for dog owners to choose from. Some of these medications can only be prescribed by a veterinarian, but in recent years, several have become available to purchase OTC.

1. Heartgard;
2. Interceptor;
3. Sentinel;
4. Advantage Multi;
5. Vectra;
6. Nexgard Spectra.

Each of these is sold in dosages according to your dog’s weight which is why it is important to regularly check your dog’s weight in order to administer the correct dose.

Your Dog Could Be Getting Dewormed Each Month!

Many pet owners don’t realize that the heartworm medications they give their pets each month also treat many of the intestinal parasites!

For example, Heartgard also treats pets for hookworms and Sentinel also treats hookworms, roundworms, and whipworms. If you’re giving your pet a monthly heartworm medication, check the packaging to see what else you are protecting your pet from.