What happens if you don’t treat worms in cats?

Worm infestations are very common in cats. Kittens are especially susceptible as they have weaker immune systems. The most common intestinal worms found in cats are roundworms, tapeworms, hookworms and whipworms. If left untreated, these parasitic worms can cause serious health problems for your cat. It’s important to be vigilant about worming your cats, especially kittens, to prevent infestations. In this article we’ll look at the different types of cat worms, how they infect your cat, the symptoms and what can happen if you don’t treat worm infestations.

What are the most common worms in cats?


Roundworms are long, spaghetti-like worms that live in a cat’s intestines. Kittens usually get roundworms from their mother’s milk. The roundworm eggs hatch in the intestinal tract, and the larvae migrate through the cat’s liver and lungs before being coughed up and swallowed. Roundworms can cause a pot-bellied appearance in kittens.


Tapeworms live in a cat’s small intestines. Cats become infected with tapeworms when they ingest infected fleas during grooming. Tapeworms absorb nutrients from the cat’s food before it can be absorbed by the cat’s body. This can lead to weight loss and poor growth. Tapeworm segments may be visible around a cat’s anus or in their stool.


Hookworms attach themselves to a cat’s small intestines and feed on blood. Kittens can become infected through their mother’s milk. Cats can also pick up hookworms from contaminated soil. The larvae enter through the skin and migrate to the intestines. Hookworms drain blood and nutrients leading to anemia, weight loss and other problems.


Whipworms live in the cecum and colon. Eggs are ingested from contaminated soil or the cat’s environment. Heavy infections can lead to bloody diarrhea, weight loss and anemia. Whipworm eggs can survive in the soil for years.

How do cats get worms?

There are a few ways cats can pick up worm infections:

From their mother – Kittens can be born infected with roundworms and hookworms if their mother has worms. The larvae are transmitted through the milk.

Fleas – Cats become infected with tapeworms when they ingest infected fleas during grooming.

Contaminated soil – Roundworm, hookworm and whipworm eggs live in contaminated soil and can be ingested when a cat grooms or has access to dirt. This is why litter boxes need to be cleaned regularly.

Rodents – Cats can become infected by eating rodents that carry worm larvae.

Raw meat – Eating raw, undercooked meat or prey can expose cats to worm larvae.

Once a cat is infected the worms lay eggs which are passed in the feces, continuing the life cycle. Eggs contaminate the environment and put other cats at risk.

What are the symptoms of worms in cats?

Intestinal worms can cause the following symptoms:

– Bloated or pot-bellied appearance
– Visible worm segments in stool or around anus
– Diarrhea
– Vomiting
– Coughing
– Weight loss
– Poor coat
– Loss of appetite
– Anemia

With heavy infestations cats may have a dull coat, seem depressed and generally unwell. Worms rob the body of nutrients leading to weight loss and failure to thrive.

Kittens are most at risk of becoming unwell as their immune systems can’t cope with a heavy parasite load. Roundworms especially can cause intestinal obstructions in kittens.

If you notice any of these symptoms, take your cat to the vet for a checkup. A fecal examination can detect worm eggs.

What happens if worms in cats are left untreated?

There can be serious consequences if worms are not treated in cats:

Malnutrition and weight loss

Intestinal worms rob the body of vital nutrients, leading to protein deficiencies, vitamin deficiencies and anemia. A heavy worm burden can stunt growth and cause weight loss in kittens.

Intestinal blockages

A large number of roundworms can clump together causing obstructions in the intestines. This is especially risky in young kittens who have narrower digestive tracts.


Parasites like roundworms damage the intestinal lining, making it harder for the body to absorb water and nutrients. This can lead to dehydration.

Collapse of the digestive system

If left untreated, eventually the gastrointestinal system can become overloaded by worms, leading to a complete collapse. Diarrhea, vomiting and weight loss become severe. This can be fatal if not treated.

Severe anemia

Certain worms like hookworms feed on blood, draining the body of red blood cells leading to severe, life-threatening anemia.

Stunted growth

The malnutrition associated with worms prevents proper growth and development in kittens. Bones may become deformed and the coat dull.

Damage to other organs

As part of their life cycle roundworm and hookworm larvae migrate through the liver, lungs and other organs. This can cause permanent damage or allow bacteria easy access to these sites.

Spread to humans (zoonosis)

Some cat worms like roundworms and hookworms can be transmitted to humans, especially children. This highlights the need to promptly treat worm infections in cats and properly clean the litter box.

Clearly allowing worms to go untreated can put your cat’s health at serious risk. In severe cases it can be fatal. This is why deworming kittens and cats on a regular schedule is so important.

How often should cats be dewormed?

Veterinarians recommend deworming kittens every 2-4 weeks until 12 weeks of age as they are most prone to heavy worm burdens.

Adult cats should be dewormed at least 4 times a year. It’s a good idea to administer a broad-spectrum dewormer that covers all intestinal parasites.

Ideally cats should be tested for worms first before deworming. A fecal exam allows your vet to detect eggs and choose the appropriate medication.

Always follow up with another fecal test 2-4 weeks after deworming to check it has been effective.

More frequent deworming may be advised for outdoor cats who hunt, or if worms are detected. Speak to your vet about the best schedule for your cat.

What is the best cat dewormer?

There are many effective cat dewormers available. Common active ingredients include:

– Pyrantel pamoate – treats roundworms and hookworms
– Praziquantel – treats tapeworms
– Ivermectin – treats roundworms
– Moxidectin – treats roundworms
– Febantel – treats roundworms and tapeworms

Broad-spectrum dewormers combine several actives to treat all common worms. Some well-known brands are Drontal, Droncit, Strongid T and Profender.

The best medication depends on the type of worms detected through fecal testing. Your vet will prescribe the ideal dewormer for your cat’s needs.

Never use dog deworming products for cats as they can be toxic. Only use medications specifically formulated for felines.

Can worms go away without treatment?

It’s very rare for a worm infestation to disappear without treatment. Even if symptoms seem to resolve, eggs continue to shed in the feces which reinfects your cat and contaminates the home. Kittens infected by their mothers tend to carry worms until treated.

In some cases an adult cat’s immune system can suppress worms to a degree. But worms thrive in the warmer intestinal environment and reinfect in cycles. Treatment is nearly always necessary to fully eliminate an infestation.

Letting worms run their natural course risks serious harm, especially for kittens who can crash fast. Don’t delay deworming if you suspect your cat has worms.

How to prevent worms in cats

You can help prevent worms with these measures:

– Deworm kittens every 2 weeks up to 12 weeks old
– Stick to a regular deworming schedule for adults
– Promptly remove feces from the litter box
– Clean the litter box weekly or more
– Keep cats indoors where possible
– Treat fleas monthly
– Have a vet exam annually and check for worms
– Don’t feed raw meat or prey

With diligent deworming and hygiene, you can help protect your cat from parasitic worms. But infections can still occur, so routine veterinary care is also important.


Worms are a very common problem, especially in kittens. But they can lead to serious illness and even death if untreated. The most common symptoms include diarrhea, vomiting, weight loss, dull coat and pot belly. Through fecal testing and deworming medications, worms can be effectively controlled. All cat owners should adopt a strict parasite prevention regime. Don’t assume worms will resolve on their own – be vigilant about identifying infections and promptly treating your cat. Consistent deworming and vet checks will keep your cat happy and worm-free.

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