Why worming is important

Parasites are not something we really like to think about, but as responsible owners it is important that we safeguard our cats and our families against them. A heavy burden of worms can cause suffering and illness in our pets, so it is necessary to prevent this. Although it is rare, some types of worms also pose a risk to human health if the eggs or larvae are ingested. This is a follow-up to our initial post on parasites a few weeks ago!


There are two main types of worms affecting cats 


Dipylidium Caninum (the flea tapeworm)

  • These are long, flat worms with segmented bodies that attach to the wall of the small intestine and absorb nutrients as they flow past
  • Once tapeworms mature, they shed their segments which pass out in the faeces and look like tiny, mobile, grains of rice.
  • The segments dry up in the environment and then break open to release tiny tapeworm eggs.
  • The eggs are then eaten by flea larvae in the environment and and they continue part of their lifecycle in this host until it matures into an adult flea and jumps onto a cat.
  • If a cat accidentally swallows the infected adult flea while grooming, it will become infected with tapeworms again.
dipylidium Caninum Lifecycle
It is very important to regularly treat your pet for fleas to help prevent tapeworm infestation.

Taenia species

  • These tapeworms need intermediate hosts such as  rabbits, rodents and other animals that may be prey for our dogs and cats.
  • The prey species may ingest the tapeworm eggs from the environment and the tapeworm larvae then start to develop inside the intermediate host.
  • Once the cat has ingested it’s prey, the tapeworm latches on to the wall of the intestine and continues its life cycle in much the same way as the flea tapeworm.


Toxocara Cati 

  • These worms generally look a lot like small noodles or spaghetti strands and live in the intestine
  • Adult roundworms mature, mate and then shed lots of tiny eggs which pass out in the faeces.
  • The eggs have a very tough shell and can remain in the environment for a long time.
  • Animals ingest the eggs through normal grooming or eating an infesced host animal.
  • When the eggs reach the animal’s intestines they hatch and the juvenile worm then burrows out of the intestines.
  • If the host is not a cat then the worm encysts (or encloses) itself into other body tissues and waits until the host is eaten by a cat.
  • If the host is a cat, that has either ingested the worm eggs or has ingested a host animal, the juvenile worms migrate through the body until they reach the lungs; here they are coughed up and then swallowed so that they end up in the intestine again.
  • The worms mature in the intestines and eventually produce eggs which are passed out in the cat’s faeces to begin the life cycle again.


Picture from CDC Website

Toxascaris Leonina

  • These Roundworms do not migrate around the body in the same way as the Toxocara species do. The second stage larvae mature in the intestine over a period of  2 to 3 months before they start producing eggs again.


  • Lungworms live in the pulmonary arteries and a heavy infestation can be fatal
  • They are transmitted to cats that eat infected rodents, slugs, snails and frogs
  • For more information on Lungworm please see the links below
Microscopic views of worms (Courtesy of Novartis)

Other less common worm types in the UK


  • In addition to living in the animal’s small intestine, the hookworm larvae can penetrate skin (usually the feet) and cause infection.
  • Hookworms are thought to infect up to 68% of the fox population.
  • These worms rarely affect cats in the UK.


  • These worms are not found in the UK, but they do pose a big risk for animals travelling abroad.
  • They are transmitted by mosquitoes and live in the pulmonary arteries and heart of infected dogs and cats.

Signs that your pet may have worms

  • Small white segments (roughly the size of a grain of rice) may be seen around your cat’s bottom area or in the faeces
  • Your cat may cough up / vomit Roundworms if he or she has a heavy infestation
  • Itchy bottoms may cause them to ‘Scoot’ along the groundWorms
  • You may see worms in your cat’s poo
  • Increased appetite
  • Coughing
  • Vomiting and/or Diarrhoea
  • Weight loss
  • Loss of coat condition
  • Pot belly (kittens)
  • Fleas

You may not realise you cat has worms at all because not all cats will show these signs. Remember, prevention is easier than cure. There is a number of over the counter dewormer for cats available. Which ones will depend on your country.

The risk to humans

Toxocariasis is thankfully rare in the UK but can happen when Roundworm larvae are ingested by a human. Usually the larvae will just die off in the human digestive tract, but in some cases the larvae survive and can migrate and encyst in organs or they reach the eye and cause blindness. Children are at a much higher risk of infection as they are often close to pets and play in outdoor areas where parasites may have been deposited.

Kids and pets

Keep your pet and the environment worm free

  • Use a veterinary recommended wormer: You should worm your pet at least 4 times a year, but more frequently if your pet hunts, likes to eat dead animals, or likes to eat poo. Be very careful about using ‘natural/herbal worming products’ as these products work by removing the worms from the animal’s digestive system but not necessarily killing the worms, meaning any eggs that are passed are still viable and will infect the next host.  (It is worth noting that commonly named ‘natural’ worming products such as Oregon Grape, Black Walnut, Wormwood, Garlic and Onions can all be highly toxic to pets if the dosage is miscalculated!)
  • Use a veterinary recommended flea treatment: Spot on treatments and tablets are usually given monthly and some veterinary recommended flea collars last for up to 8 months . Make sure you use a house-hold spray yearly to kill any flea eggs or larvae in the home environment.
  • Scoop the poop:Cat litter trays and outside toileting areas should be scooped out daily and properly cleaned at least once a week.
  • Good personal hygiene and making sure children wash their hands: Especially after stroking pets and playing outside.  Kissing your cat or letting him or her lick you will put you more at risk, especially if you are immunocompromised.
  • Speak to your veterinary nurse: He or she can advise you on the safest and most effective parasite treatments for your cat as well as how often you need to give them.

Useful Links 

For more information on the Flea lifecycle

For more information on Lungworm

Merial Parasite Information – Parasite Party

Novartis Worming information – Worm Patrol

Bayer Animal Health parasite information – Its A Jungle Out There

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16 thoughts on “Why worming is important

  1. Prior-2001 says:

    thanks for the great info here! I was recently visiting a church in KS here in the US and they were pushing pet adoption and had pets on site / but in all the energy and pitch speeches – the importance of de-worming and other care was not mentioned – and I think some people minimize this – hmmm

  2. angela1313 says:

    Outstanding article. Most rescue groups I know de-worm on intake, especially kittens of feral moms, but once the cat is adopted I think people think mostly of flea prevention. Just another reason I’m glad my cats are indoor only.

  3. FreeMurrli says:

    Parasites can be really dangerious, true. Murrli gets de-wormed four times a year, and she has not had any visible worms for years now. I use a drug called “Flubenol KH”, which is available in the pharmacies here and Murli gets it in her food. She is very suspicious but eats it. 🙂

    In spring and early summer, Murrli gets ticks, mainly on her neck and face. I use “Frontline”on her neck. I cannot put a collar on her, it would drive her crazy. 🙂

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