Why Do I Need To Deworm My Cat?

silver tabby kitten climbing a tree

Last updated on February 27th, 2024 at 08:23 pm

If you own a cat, you may have been told you need to have it dewormed. You might also have asked “why?”, especially if your cat is perfectly healthy.

Cats can suffer from significant health issues such as vomiting, diarrhea, loss of appetite, and poor growth, or even death due to worms. Deworming your cat is an important part of keeping them healthy. It’s also important to deworm cats regularly because some worms, such as roundworms and hookworms, can also infect humans.

Not convinced? Let’s look at this a little closer.

Even A Healthy Looking Cat Can Have Worms

It is indeed possible for a cat to have worms even if it appears healthy and you have never seen any visible signs of worms. There are several reasons why this may occur:

  • Dormant or Inactive Worms: Some types of worms can remain in a dormant or inactive state within a cat’s body. These worms may not cause obvious symptoms or be visible in the cat’s feces.
  • Intermittent Shedding of Worms: The shedding of worms can be intermittent, and the timing may not coincide with when you examine the feces.
  • Subclinical Infections: Some cats may experience what is known as subclinical or asymptomatic infections. This means that they can carry a low number of worms or have mild infestations that do not cause obvious signs of illness.
  • Immune System Response: Cats with a healthy immune system can often keep worm populations in check. Their immune response may prevent the worms from causing significant harm or multiplying to a level where symptoms become evident.
  • Lifecycle of the Worms: The lifecycle of various worms can also contribute to the challenge of detecting them. For instance, certain types of worms have migratory stages or can lay eggs that take time to mature and become detectable. This means that the presence of worms may not be immediately apparent even if an infestation exists.

Given these factors, it is important to understand that the absence of visible worms or symptoms does not guarantee that your cat is free from worms. 

Worms Can Cause Health Problems In Cats

Worms, such as roundworms, hookworms, tapeworms, and whipworms, are common parasites that can infect cats. The parasites have the potential to cause various health problems for your cat and could also affect your and your family’s health.

First and foremost, worms can compromise your cat’s overall health and well-being. When worms infest a cat’s gastrointestinal tract, they feed on vital nutrients that are meant to nourish the cat’s body.

As a result, the cat may experience weight loss, weakness, and a lack of energy. The presence of worms can also lead to a dull coat, diarrhea, vomiting, and decreased appetite.

If left untreated, worm infestations can escalate and cause more serious health problems. For instance, certain worms can cause anemia by feeding on the cat’s blood, leading to a decrease in red blood cells and oxygen-carrying capacity. This can result in fatigue, pale gums, and weakness.

Worms can also cause malnutrition by depriving the cat of essential nutrients, which can hinder growth and development, especially in kittens.

Heavy worm burdens cause additional problems. If a cat has a heavy infestation of hookworms, for example, these parasites can attach themselves to the intestinal wall potentially leading to internal bleeding. This can be especially dangerous for young kittens or cats with weakened immune systems.

ginger tabby cat looking into the camera

Cat Worms Can Cause Health Problems In People

There is also a human health risk related to worms in cats. Certain parasites, such as roundworms and hookworms, can be transmitted to humans through contact with contaminated soil, feces, or infected animals.

This is particularly concerning if you have young children who are more susceptible to infections. In humans, these worms can cause various health issues, including abdominal pain, diarrhea, and, in rare cases, more severe complications.

Ask Your Veterinarian What Dewormer You Should Use For Your Cat

Regular deworming is necessary for preventing these issues and ensuring the overall health of your cat. By administering appropriate deworming treatments as recommended by your veterinarian, you can effectively eliminate worms and their potential risks.

However, it’s important to note that not all dewormers are effective against every type of worm, which is why consulting with a veterinarian is essential. They can help determine the appropriate deworming schedule and recommend the right medication for your cat’s specific needs.

Only Give Cats Dewormers That Are Meant For Cats

It is also very important that you only use a dewormer that is formulated specifically for cats.

Do not give a cat dewormer that is meant for dogs. What is safe for one species is not necessarily safe for the other, as they have differences in their physiology and how they metabolize drugs.

Not all medications can be used in both species, and for those medications that can be used in both species the amount that can be safely given to each often differs.

Take Drontal®, for example, a popular dewormer that has formulations for cats OR dogs, but does not have one formulation for both. For cats, the tablet contains 18.2 mg praziquantel and 72.6 mg pyrantel base as pyrantel pamoate. For small dogs, the tablets contain 22.7 mg praziquantel, 22.7 mg pyrantel base as pyrantel pamoate and 113.4 mg febantel.

We can see here much less pyrantel is given to dogs as compared to cats, plus the dogs are getting febantel which is not given in the cat tablets. So it would be inappropriate, even dangerous, to give the dog version of this dewormer to a cat.


Worms can be a serious health issue in cats and are potentially hazardous to humans as well. Regular deworming is key for preventing these problems, but it’s important that you only use products specifically meant for cats.

Always consult with your veterinarian before giving your cat any kind of medication so that you can ensure they get the appropriate dewormer for their specific needs.

Note: This information is a general guideline and should not substitute professional veterinary advice. Always consult with your veterinarian for specific guidance and treatment recommendations for your cat’s unique situation.

alert silver tabby  cat sitting in green grass


  • Dr. Wendy Wilkins, DVM, PhD

    Dr. Wendy Wilkins is an experienced veterinarian and epidemiologist with over 20 years of expertise. She holds a Doctor of Veterinary Medicine (DVM) degree and a Doctorate in Epidemiology from the University of Saskatchewan. Throughout her career, Dr. Wilkins has excelled in clinical practice, academia, research, and regulatory veterinary medicine. She is a respected voice in knowledge dissemination, delivering factual information in a readable and understandable manner through articles, books, and public engagements.

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