Parasites are creatures that can live on or inside your body and take nourishment from you to survive, including fleas, lice, worms, and single-celled organisms called protozoa. Parasites can infect many different species, including humans, cats and dogs, and some can even be shared between species so it’s very important to avoid anyone in the family from becoming infected with these critters! 

What types of worms are there?

There are a number of common parasitic worms that can infect your cat during their life. These worms can live in different parts of your cats’ body (heart, lungs, intestines), causing different clinical signs, but usually all will lead to ill-health in your pet. Due to this, it’s very important to prevent our pets becoming infected with these parasites.


Parasitic worms that can infect your cats’ heart are called heartworm. Heartworm disease has been found in pets all throughout mainland Australia. While heartworm is not as common in cats as it is in dogs, there is still a risk of infection and shouldn’t be overlooked. 


Lungworms are small thin worms that can live in the airways of the lung and can cause damage to lung tissue. Infection with lungworms are not common, however this parasitic worm is still present in Australia.  

Intestinal worms

There are a number of parasitic intestinal worms that can infect your cat during their life. The most common worms that affect cats in Australia are roundworms, hookworms and tapeworms. These worms live inside the animals’ gastrointestinal tract, specifically the small intestine. Roundworms and hookworms are short with rounded bodies. Kittens are more commonly infected with roundworms. Tapeworms are long with a flat body that is comprised of multiple small segments. Tapeworms commonly occur concurrently with flea infestations and usually affect adult cats. 

How can my cat become infected?

Any cat can become infected with parasitic worms, including both outdoor and indoor only cats. 


Heartworms are transmitted by mosquitoes and these worms spend some of their life stages inside these insects. To infect an animal, an infected mosquito must bite your cat and inject heartworm larvae into their blood, these larvae then travel around the body as they develop into adults. Adult worms live in the animals’ heart where they can release larvae into the blood that can infect future mosquitoes when they bite the animal. 


Lungworm infections are usually through the ingestion of infected small animals (including snails, mice, frogs, bids, lizards). Once ingested, larvae present can travel through the intestines and migrate to the lungs where the larvae develop into adults and reproduce. Eggs are produced in the lungs, then coughed out or swallowed allowing excretion in the faeces. 

Intestinal worms (Roundworms, Hookworms and Tapeworms)

Ingestion of parasitic eggs, larvae or worm segments lead to intestinal infection in cats. This ingestion can occur through contaminated soil, contact with contaminated faeces, ingestion of infected small animals or even through mothers’ milk. (This is why we assume all cats are likely to be infected with some roundworms, even tiny kittens! – Editor.)

Intestinal worms are commonly found in the small intestine but can migrate to the eyes and skin during certain life stages. Adult worms (roundworms and hookworms) lay eggs in the small intestine, while tapeworms release segments containing eggs, these eggs then excreted in the faeces.      

What are the clinical signs?

Cats infected with parasitic worms do not always show signs of infection, however worms can cause ill health in cats. Clinical signs are more common in kittens, older cats and those animals with poor immune systems. Some common symptoms that may be seen include:

  • Lethargy
  • Inappetence
  • Diarrhoea (blood may or may not be present)
  • Vomiting
  • Coughing (blood may or may not be present)
  • Sneezing 
  • Nasal discharge
  • Breathing changes or difficulty 
  • Development of a pot belly 
  • Weight loss  
  • Death 

Treatment for worms

There are numerous products available to prevent parasites in your cat and the variety can be very confusing. These treatments can contain different active drugs, treat singular or multiple parasites, and can be species or weight specific. Not all of these antiparasitic treatments are as effective or safe as each other and many can be inferior and ineffective in preventing parasitic infections. 

It is important to ensure you are giving the correct species-specific treatment and dosage rate to your cat when administering antiparasitic drugs. These drugs can be dangerous if incorrectly administered and negatively impact on your cat’s health. For the best advice on what treatment is most suitable for your cat, it is best to check with your regular veterinarian. 

Depending on your cats age, history, weight, where they live, and their exposure risk, your veterinarian can develop an appropriate personalised treatment plan for your cat. Additionally, veterinarians can choose treatments based on your preferences including the frequency and method of application (spot on vs tablet). 

If you have any concerns about worming your cat or if you suspect your cat may have worms, don’t hesitate to contact your local vet clinic for advice or assistance to ensure your cat is dewormed safely and effectively.  

How often should I treat?

Regular worming is essential for the health and wellbeing of your cat. It is important that parasite prevention is continued for the lifetime of your pet. The timing of treatment may vary depending on your cat’s treatment plan and the antiparasitic product being used. A general schedule could look similar to this:

Heartworm and Lungworm 
  • Monthly (spot on or tablet) 
Intestinal worms 
  • Kittens (4-12 weeks) – every fortnight 
  • 12 weeks to 6 months – every month   
  • 6 months to adults – every 1, 3 or 6 months (depending on the antiparasitic product)  

Can your cat infect you with worms?

Yes, some worm species are zoonotic meaning they can pass from an animal to a human. This means that your cat can share their worms with you! Infections commonly occur due to poor hygiene practices leading to the ingestion of eggs or larvae by humans. There are a number of simple steps you can take to protect yourself and your family from a possible infection.

  • Ensure that you regularly deworm your cat  
  • Make sure you clean up after your cat by regularly removing faeces from litter trays or the backyard 
  • Wash your hands frequently after touching your cat or cleaning up after them
  • Teach your family good hand hygiene (especially young children) 
  • Practice correct food-handling to reduce the risk of transmission from contaminated food 


Remember, prevention is key and ensuring you have a good parasitic preventative plan in place should ensure your cat can stay healthy, happy and parasite free! If you have any concerns or want further advice or information, don’t hesitate to contact your local veterinarian who will always be happy to help.