Worms and deworming in cats
Intestinal parasites in cats: which worms occur, when to deworm, proven effective products and why flea control is essential.
Short & honest
Strong evidence (grade A): modern dewormers are proven effective and safe. Deworming frequency depends on the cat's risk class; there is no scientific evidence for natural alternatives.
Veterinary review not yet completed
This page is awaiting review by a registered veterinary surgeon. Until then, treat the text as education based on the sources listed — not as a verified veterinary judgement.
What are intestinal parasites in cats?
Intestinal parasites are worms that live in the gastrointestinal tract of the cat. Mild infections often proceed without symptoms; heavy infections cause diarrhoea, weight loss and in kittens a typically distended abdomen.
The three most common species are [1][2]:
- Roundworms (Toxocara cati) — the most common intestinal parasite; found in ~13% of house cats and ~30% of stray cats
- Tapeworms (Dipylidium caninum, Taenia taeniiformis) — D. caninum uses the flea as an obligatory intermediate host
- Hookworms (Ancylostoma tubaeforme) — can cause blood loss and anaemia
T. cati is also a zoonosis: humans, particularly children, can become infected via contaminated soil or cat faeces. Larval migration can lead to ocular larva migrans — resulting in blindness — or neurological damage. The CDC lists T. cati among the priority parasitoses [2].
When and how often to deworm?
ESCCAP (2025) advises frequency based on risk class — no fixed calendar for every cat [1]:
| Situation | Recommended frequency |
|---|---|
| Indoor cats | At least 4× per year |
| Outdoor cats / hunters / raw feeding | Monthly |
| Kittens (up to 8 weeks) | At 2, 4, 6 and 8 weeks |
| Low-risk cats | Faecal examination as an alternative |
Kittens are dewormed early and frequently due to transmission of T. cati via mother's milk (lactogenic transmission) [1].
Proven effective agents
Active substances with strong evidence [1]:
- Pyrantel or fenbendazole — effective against roundworms and hookworms
- Praziquantel — effective against tapeworms
- Broad-spectrum products combine multiple active substances in one treatment
Flea control is essential for tapeworms
Dipylidium caninum spreads exclusively via fleas as an intermediate host. A cat becomes reinfected by ingesting an infected flea during grooming. Deworming without simultaneous flea control inevitably leads to reinfection with tapeworms [3].
Faecal examination as an alternative to blind deworming
In low-risk cats, targeted faecal examination (flotation or PCR) is more reliable than routine blind deworming. The copro-antigen test has the highest sensitivity for detecting Dipylidium. A veterinary surgeon can treat in a targeted and specific manner based on the result [1].
No evidence for natural alternatives
There is no reliable scientific evidence that 'natural' remedies — such as garlic, pumpkin seeds or diatomaceous earth — effectively combat intestinal parasites in cats. Delaying proven treatment increases the risk of illness for the cat. In the case of T. cati, it also increases the risk of infection for humans in the household, particularly children.
Additional measures such as hygiene, regular faecal checks and flea prevention support the treatment. They do not replace proven medicinal products.
Why this verdict?
Grade A is based on the ESCCAP guideline 7th edition (2025) — the European scientific reference for parasite control in companion animals — combined with a systematic review with meta-analysis on *Toxocara cati* in cats (39 studies, 2024) and the CAPC clinical guideline for *Dipylidium caninum*. All three are high-quality sources with broad epidemiological support. Limitation: prevalence figures vary by region and study method; faecal testing yields more representative data than autopsy-based estimates [1][2][3].
Legal status (Netherlands)
Some dewormers for cats are available over the counter in the Netherlands; combination preparations and broad-spectrum products are generally prescription-only. A veterinary surgeon determines which product is suitable based on risk class, weight and any other medication. Establishing a diagnosis and indicating treatment for a sick animal is reserved for veterinary surgeons (Wet Dieren [Animals Act], art. 2.1).
Sources
- [1] ESCCAP Guideline 01 – Worm Control in Dogs and Cats (7th edition, June 2025). ESCCAP (European Scientific Counsel Companion Animal Parasites), 2025. Guideline source ↗
- [2] Toxocara cati Infection in Cats (Felis catus): A Systematic Review and Meta-Analysis. Animals (Basel) / MDPI, 2024. Meta-analysis doi:10.3390/ani14071022
- [3] Dipylidium caninum – Clinical Care Guidelines. Companion Animal Parasite Council (CAPC). Guideline source ↗