How Do I Find The Right Dewormer For My Dog?

Watch out worms 🚫🪱

dog with worms

Deworming sounds like a pretty gross concept, but it’s a necessary part of keeping your dog happy and healthy.

But if you have a new pup, you might be wondering how you set about doing it — and also what even are those worms you’re fighting?

The Dodo spoke to Dr. Bernadine Cruz, a veterinarian at Laguna Hills Animal Hospital in California, to find out everything you need to know about deworming dogs, and to get information on how to choose the right dewormer for your dog.

What are worms in dogs?

Worms are a type of parasite that are common in dogs.

Dogs are popular hosts for worms and other parasites because they spend a lot of time sniffing, rolling in dirt and eating things they shouldn’t (including poop — ew), which means it’s easy to pick them up.

There are five main types of worms that dogs can contract. The first four are intestinal worms, while heartworms live in dogs’ hearts, lungs and blood vessels:

  • Roundworm (the most common type)
  • Tapeworm
  • Hookworm
  • Whipworm
  • Heartworm

How do dogs get worms?

Most puppies who have worms get them from their moms. If a dog has ever had roundworms, dormant worms can stay in her body and be activated by hormones when she becomes pregnant. These can be passed to her puppies before they are born or through nursing.

Adult dogs can contract worms by eating soil or feces that contains worms. Which means there actually is a good reason why you should stop your dog from eating poop (besides the gross factor).

“Do not allow a pet to eat another pet’s feces. The most common means of parasite transmission is oral-fecal route,” Dr. Cruz told The Dodo.

Dogs can also contract worms by eating fleas, which can contain tapeworm larvae, while grooming.

Mosquito bites can also lead to heartworms if your pup is bitten by an infected bug.

So basically, there are lots of opportunities in the average dog’s life where he may pick up a worm infestation — which is why it’s so important to keep him on a good-quality preventative medication.

What are the symptoms of worms in dogs?

So once your dog actually gets worms, what will happen to him?

“Depending on the worm, the age of the pet [and] the degree of the parasitic load (or how many worms are present), a pet may vomit them up [or] may pass them in their stool,” Dr. Cruz said.

But that doesn’t mean all the worms come out on their own — a lot of them will stay inside your dog and cause health issues (yuck). Symptoms of worms in dogs can include things like:

  • Weight loss
  • A swollen belly
  • Scooting (dragging their butt across the floor)
  • A dull coat
  • Digestive issues
  • Lethargy
  • Coughing or difficulty breathing

“The most accurate way of determining if internal parasites are present is to bring a fresh stool sample to your veterinarian for testing,” Dr. Cruz said. (If you think your pup has worms, ask your vet how to collect a sample.)

What is deworming?

First of all — what exactly is deworming? Dewormer medicines are given as preventative medication to stop worms from growing, and as a treatment to kill worms in your dog’s body.

So if your pup does run into a situation where he’d normally contract worms, the medications make it so your dog’s body is an inhospitable host, which stops an infection from happening.

How often should you deworm your dog?

If you’re getting a puppy, you should start deworming him as soon as you get him.

Puppies should be dewormed every two weeks until they reach 12 weeks of age, then monthly until they are 6 months old because they’re more susceptible to worms than adult dogs are.

This is because a puppy can contract worms through their mom’s milk and is often in close contact with other puppies in his litter, which can cause infection to spread.

Puppies also don’t have strong immune systems yet, so they aren’t able to fight infections as easily as adult dogs.

With adult dogs, you should give preventative deworming medicine at least every three months — follow your vet’s advice and the instructions on the packaging of your dewormer.

How to choose a dewormer for your dog

While there are several OTC (over-the-counter) medications available, Dr. Cruz said it’s important to consult with your vet before choosing a dewormer, as many of the readily available options aren’t actually that effective.

“The safest and most effective medications are available by prescription only,” Dr. Cruz said. “The forms that are available at feed stores and pet stores are often given for the wrong type of parasite and [are] not effective in eradicating the parasite.”

There are different types of dewormers for different types of worms, and your vet will help you decide on the best treatment for the type of worm your dog has (or is likely to pick up based on his lifestyle).

“The determination of which medication is best for your dog should be based on a dialogue between you and your veterinarian,” Dr. Cruz said. “Does your pet readily accept tablets [or] prefer chews [or] topicals, [as well as] your price sensitivity, your lifestyle and that of your pets.”

So avoid self-treating your dog, and double-check with your vet about the type of worm and type of medicine they advise before buying.

Here are some popular dewormers to ask your vet about:


We independently pick all the products we recommend because we love them and think you will too. If you buy a product from a link on our site, we may earn a commission.


HEARTGARD Plus Soft Chew for Dogs

This heartworm preventative medication kills heartworms and treats and controls roundworms and hookworms. It’s a real beef chew that your dog will actually enjoy taking.

TRIFEXIS Chewable Tablets for Dogs

This is an all-in-one deworming medicine — in addition to preventing heartworm and controlling intestinal worms (hookworm, roundworm and whipworm), it also kills and prevents fleas.

DRONTAL Plus Chewable Tablet for Small Dogs and Puppies

Drontal Plus is a chewable tablet that treats a bunch of different intestinal worms, including tapeworms, hookworms, roundworms and whipworms.

ADVANTAGE MULTI Topical Solution for Dogs

If your dog refuses to take oral medicines, you could try this topical dewormer instead. Apply Advantage Multi to your dog monthly to prevent heartworm, treat circulating microfilariae in heartworm-positive dogs and prevent and control fleas and mange.

INTERCEPTOR PLUS Soft Chews for Dogs

This medicine prevents heartworm and treats and controls roundworm, hookworm, whipworm and tapeworm. It also treats tapeworm infections caused by fleas.

SIMPARICA TRIO Chewable Tablet for Dogs

This monthly dewormer prevents heartworm disease, treats and controls roundworm and hookworm and controls flea and tick infestations. It comes as a chewable liver-flavored tablet, so your pup will think he’s getting a treat.

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