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Cat roundworms
Roundworms are the most common intestinal parasites in cats. These are white, cylindrical worms, several centimeters long, whose appearance is reminiscent of spaghetti. They live in the small intestine and feed at the animal's expense. Kitt...
What is it?
Roundworms are the most common intestinal parasites in cats. These are white, cylindrical worms, several centimeters long, whose appearance is reminiscent of spaghetti.
They live in the small intestine and feed at the animal's expense. Kittens are the most affected and the most fragile.
An adult cat can harbor worms without showing any signs while contaminating its environment. This is an essential point: the absence of symptoms does not mean the absence of parasites.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
In adults, the infestation very often goes unnoticed.
In kittens, the belly is swollen and tense, contrasting with general thinness.
Vomiting, sometimes with visible spaghetti-like worms.
Diarrhea or loose stools, sometimes containing worms.
Coat dull, pitted, poorly maintained.
Slowed growth despite a preserved appetite.
Transient cough in some kittens, linked to the passage of larvae through the lungs.
In massive infestations of the kitten, marked depression and weakening.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The parasite responsible in cats is mainly Toxocara cati.
Adult worms lay a very large quantity of eggs in the intestine, which are eliminated in the stools.
These eggs become infective in the external environment after a few days or weeks and resist for a very long time in the soil, including in the cold.
Once swallowed, they release larvae which migrate through the body before returning to the intestine where they become adults.
Certain larvae encyst in the tissues of the cat and reactivate during breastfeeding, which explains the very early contamination of kittens.
Kittens, due to transmission through breast milk and their immature immunity.
Cats having access to the outdoors and hunting.
Group life: shelters, breeding grounds, colonies.
Pregnant and lactating cats.
Lack of regular deworming program.
Sandboxes, gardens and areas shared with other animals.
Diet based on raw meat or prey.
Transmission
By ingestion of eggs present in the ground, earth, sand, grass or on soiled objects, then swallowed during grooming.
Through breast milk: the cat transmits larvae to her kittens during breastfeeding, which makes early deworming essential.
Through the consumption of prey such as rodents and birds, which harbor waiting larvae.
By the soles of shoes and objects brought from outside: a strictly indoor cat is not completely safe.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian looks for signs of infestation upon examination and assesses the general condition, especially in the kitten.
A stool analysis reveals the eggs of the parasite; as their emission is irregular, sampling over several days increases the reliability of the result.
Worms passed in the stools or vomit can be brought to the office: they are referred immediately.
An examination of all animals in the household is recommended, as a single parasitized cat contaminates the common environment.
The veterinarian adapts the protocol to the cat's lifestyle rather than applying a single rule.
Treatment
Treatment is based on internal antiparasitics prescribed by the veterinarian, in the form of tablets, pastes or products to be applied to the skin.
The choice of molecule and rhythm depends on the age of the cat, its weight, its state of health and the parasite in question: this is why a product purchased without advice, or intended for another species, can be ineffective or even dangerous.
A second administration is often necessary to eliminate worms from the larvae which were not yet in the intestine during the first treatment.
In heavily parasitized kittens, general support is sometimes necessary at the same time.
All cats in the household are treated at the same time, otherwise recontamination is immediate.
Rigorous cleaning of litter and sleeping areas accompanies treatment.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Follow a deworming program defined by the veterinarian according to the cat's lifestyle: kittens must be treated very early and closely, the lactating cat at the same time as her litter.
Pick up stools daily and clean the litter box every day: eggs become infestation after just a few days.
Wash your hands after handling litter, gardening or touching a cat, and do the same for children.
Cover children's sandboxes when not in use.
Avoid raw meat and limit hunting when possible.
Wash garden fruits and vegetables thoroughly.
Have stools analyzed regularly, especially in homes with young children.
Possible complications
Obstruction of the intestine by a pack of worms in heavily infested kittens, emergency surgical situation.
Long-term growth retardation.
Dehydration and weakness due to repeated diarrhea and vomiting.
Lung damage linked to the migration of larvae in very young animals.
Long-lasting contamination of the environment, the eggs persisting for several years in the soil.
When to see a veterinarian
You see white worms in your cat's stool or vomit.
Your kitten has a swollen belly and is not gaining weight.
Vomiting or diarrhea persists for more than twenty-four hours in a kitten.
Your cat loses weight or its coat becomes dull without explanation.
You have just adopted a cat or kitten with an unknown deworming history.
You don't know which product to use or how often: ask for advice rather than buying at random.
Transmission to humans
Cat roundworms are transmissible to humans. Humans become contaminated by unknowingly swallowing eggs present in the earth, sand or on soiled hands; he does not become infected by simply stroking a cat. Children are most exposed because they play on the ground, in sandboxes and put their hands in their mouths. In humans, the larvae do not become adults but migrate into the tissues; they can cause digestive and respiratory problems, and more rarely eye or neurological damage. The measures that really protect are simple: regular deworming of cats according to the veterinarian's recommendations, daily collection of stools and cleaning of the litter box, washing of hands after contact with the ground or the animal and before meals, covered sandboxes, washing of fruits and vegetables. If in doubt about human contamination, a doctor should be consulted, and it is useful to notify him of the presence of animals in the home.
Prognosis
In adult cats, the treatment is very effective and recovery is the rule.
In kittens taken into care in time, growth resumes normally once the parasites are eliminated.
The main risk is not treatment failure but recontamination: without litter hygiene and regular deworming, the infestation returns.
Frequently asked questions
My cat never goes out, should I still deworm him?
Yes. Eggs can be brought home under soles, and a cat can pass larvae to her kittens. The pace is simply adapted by the veterinarian to a less exposed lifestyle.
I don't see any worms in the stool, is my cat safe?
No. The eggs are microscopic and adult worms are not always emitted. Many parasitized cats show nothing while contaminating their environment.
Can my children get worms from my cat?
Yes, by swallowing eggs present in the earth, sand or on dirty hands, not by stroking the cat. Hand washing, stool collection and regular deworming greatly reduce this risk.
Are all dewormers the same?
No. They do not cover the same parasites and some dog products are toxic to cats. The choice is made with the veterinarian, according to age, weight and lifestyle.
References
ESCCAP — European Scientific Counsel Companion Animal Parasites
CDC — Centers for Disease Control and Prevention
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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