Can You Use Dog Dewormer on Cats?

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Written by: Celestine Gomez
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My dog has just caught roundworms, which isn’t a surprise knowing that he’s a curious eater.

But lately, I’ve noticed that my cat may have also picked up the worms from him. Since my dog is already on a dewormer, I thought maybe I can just give my cat the same medication.

However, I suddenly felt the need to make sure that this won’t cause any harm to my feline baby.

So, can you use dog dewormer on cats?

Even if your cat picked up the worms from your dog, giving your cat a dog dewormer isn’t recommended. The reason for this is that the ingredient quantities and recommended doses vary for both dog and cat dewormers. Besides, there’s always the possibility that your cat caught another type of worm.

In this article, we’ll talk about this topic in detail. So, let’s jump right into it!

Why Can’t I Give My Cat a Dog Dewormer?

It’s not that the pharmaceutical companies are trying to rip you off. There are actual facts as to why you can’t use the same dewormer on both your cat and dog.

Vet giving cat medicine with a syringe

Ingredient Quantities Vary

Dog and cat dewormers may have the same ingredients, but the amounts of the ingredients in pet-specific medications differ.

So, ingredient quantities that work for your dog may not work for your cat, and vice versa.

The difference in the ingredient amounts can also be unsafe for your cat. That’s why it’s never recommended to use dog medication for your cat unless your vet instructs you to do so.

Recommended Doses Vary

The recommended dewormer doses change depending on the size of your pet. For example, a 4lbs dog requires a smaller dose than a 30lbs dog.

The same goes for your cat. If your cat is smaller or bigger than your dog, you can’t give her the same dewormer dose as your dog.

Different Worms Require Different Medication

Cats can contract the same types of worms as dogs. This, however, doesn’t rule out the possibility that your cat may have a different type of worm than your dog.

In that situation, your dog dewormer will almost certainly not work on your cat.

What Happens if I Give My Cat a Dog Dewormer?

If you give your cat a dog dewormer by accident, don’t freak out. She probably won’t experience any side effects from one dose.

However, if your cat takes more doses, there’s a higher risk that she’ll get sick. In this case, stop giving her the medication and don’t put her on another medication right after.

Wait for a couple of days to see if there are any poisoning symptoms or abnormal behavior.

Look for symptoms, such as:

  • Drooling
  • Diarrhea
  • Vomiting
  • Lethargy
  • Loss of appetite
  • Skin inflammation
  • Swelling
  • Urination abnormalities
  • Abdominal pain
  • Hair loss
  • Fever

Some of these symptoms are common poisoning symptoms. The reason for that is that some dog medications can be poisonous to cats.

That’s why you need to call your vet the moment you notice any of the above-listed signs.

However, if your cat is doing well after around a week, it’s time to give her a suitable dewormer.

How Can I Keep My Cat From Picking Up My Dog’s Worms?

If your dog has worms and your cat is usually in his company, she most likely has them as well. So, I recommend letting your vet take a look at your cat too, just to check whether she caught them.

If your vet confirms she has worms, all you need to do is to give her the dewormer your vet recommends. Otherwise, take the following precautions:

Cat being checked by vet
  • Always keep your cat’s litter box clean
  • Try to keep your cat inside, especially if she likes chasing birds, mice, and other rodents.
  • If possible, keep your cat away from your dog until he has gotten rid of all the worms. Cats may be tempted to groom their canine companions, resulting in worm infection
  • Deworm your pets as frequently as recommended by your vet
  • Try your best to eliminate fleas as they can cause worms in both dogs and cats
  • Test your pets’ stool at least once a year to make sure they’re not infested with parasites of any kind

How Often Should I Get My Cat and Dog Dewormed?

Frequent deworming is necessary to keep your pets worm-free.

If your feline is an adult, she should be dewormed every three months. If you have kittens, you should ask your vet to put them on a specific deworming schedule.

Usually, kittens need to be dewormed every two weeks from the day they’re born until they’re old enough. Of course, this should be done under your vet’s supervision.

As for feline hunters, they’re the most susceptible to worms. That’s why they should be dewormed monthly.

In contrast, your dog should be dewormed every three months. Puppies, like kittens, need to be dewormed frequently when they’re young. Your vet should help you put a deworming schedule for them.


Here are answers to a couple of frequently asked questions that we gathered for you:

1.   Do I have to go to the vet to deworm my cat?

Some people claim that some natural remedies can deworm your cat or dog. However, there isn’t any scientific evidence that these remedies work.

So, it’s safer to take your pets to their vet to provide your pet with the most suitable medication.

2.   Can you deworm a dog or cat too often?

Yes, you can deworm your cat or dog too often, and it has no benefit for them. In fact, deworming your pet too often can do more harm than good.

Deworming your pet too often can lead to an overdose or a severe poisoning case. So, it’s always best to follow a deworming schedule devised by a vet specifically for your pet.


It can seem convenient to give our cats the same dewormers as our dogs. However, this can have negative side effects on our feline buddies.

To be on the safe side, it’s best to ask the vet to prescribe the right dewormer for our cats.

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Celestine Gomez

I'm Celestine Gomez, worked for 5 years in an animal shelter in Los Angeles, California. Having noticed the inherent passion and zeal in me to care for pets, I took a step further to create a team of I and like-minded individuals to provide an informative resource in order to broaden the knowledge base of a regular pet owners.