Did you know a dewormed cat can still have worms? Why don’t standard dewormers work on ALL worms? Keep reading to find out.

As a first-time foster parent (at least, officially) for kittens, I was unaware of the fact that a dewormed cat can still have worms, even after being given a dewormer.

This, however, does not mean that standard dewormers don’t kill worms — they just don’t kill ALL worms.

What Worms Do Standard Dewormers Kill?

The most common pests seen in young kittens are roundworms. Most standard dewormers will kill roundworms (with some also targeting whipworms and hookworms). Specialized dewormers like Heartgard treat heartworms, but the toughest customer is the tapeworm.

How Do Cats Get Tapeworms?

Cats become infected with tapeworms through ingestion of flea larvae that are carrying tapeworm eggs. This can happen when the cat feasts on an animal infected with fleas or from self-grooming in response to flea bites on their own body.

Once the eggs hatch, the tapeworm will latch onto the small intestine and continue to grow.

Why Don’t Standard Dewormers Kill Tapeworms?

Tapeworms require a medication called Praziquantel, which is not typically present in standard dewormers. Pet Coach’s Angel Alvarado, LVT describes Praziquantel’s effects as such:

Praziquantel, and similar drugs, work by ‘dissolving’ the tapeworm’s skin. This is effective in killing the parasite since they absorb nutrients through the skin. Other parasites have heads or mouth parts through which they feed. Other dewormers interfere with larval, egg or adult development or actually cause paralysis to kill parasites.”

Basically, the tapeworm cannot survive losing its skin. This effect is also seen in cleaning products like Bean & Lily where surfactants are used to break down bacteria walls. Without its ‘skin’ to hold it together, the bacteria dies.

Think of Praziquantel as the needle that breaks the skin of a water balloon. Without latex rubber to hold its shape, the water goes everywhere.

If My Dewormed Cat Can Still Have Worms, Why Not Include Praziquantel In Standard Dewormers?

An excellent question. Tapeworms are less common because rather than spreading through contact with feces, their eggs have to be ingested in order to be transmitted. Still, why wouldn’t Praziquantel be included in standard dewormers as a preventative measure?

The answer is in the compounding of the drug. Praziquantel is a tricky drug to compound (the process of chemically combining two or more elements). Unless it is done correctly, it loses its effectiveness. This makes the process more expensive.

If Praziquantel were included with every standard dewormer, they would be A LOT more expensive. If the process is expensive, the end result will be expensive.

(Disclaimer: I do not have an internet source for this because I asked my local vet. She explained the process scientifically, and I made sure I understood it perfectly so I could put it in layman’s terms here. If anyone has a source for the above explanation that I could include, please email me at themeowplace@gmail.com.)

Should You Give Your Cat Tapeworm Dewormer?

If you suspect your cat has tapeworms, don’t give them Praziquantel without an official diagnosis. This medication can be very hard on your cat’s system, especially with a young kitten.

My foster kitten Cheerio had to get a dose of Profender (a topical tapeworm medication). She later experienced a few of the common side effects of the medication, including decreased appetite, diarrhea and vomiting. Needless to say, it was not a pleasant experience for her, but it did get rid of the tapeworms.

Always consult with your veterinarian before giving your cat medications.

This post is not intended as a substitute for medical advice. Always consult with your veterinarian on the right treatment plan for your cat. If you feel uncomfortable with the advice they give you, or you desire a more holistic approach to treatment, get a second opinion from another vet before trying at-home treatments.