Last Updated on June 27, 2021 by Julia Wilson
Several parasitic worms are common to cats, but many cat owners are not sure how to identify the type of worm your cat may have.
As you will read, most of the time worms remain in hiding, so your cat may be infected with worms, but you are unaware. This highlights the importance of a regular worming schedule, starting from two weeks of age.
Even indoor cats can be infected with worms, as you will see below, roundworms are transmitted to kittens even before they are born, indoor cats can get fleas, which come inside on people’s clothing, open doors or windows, fleas transmit tapeworm.
Toxocara cati (feline roundworms) live in the intestinal tract of cats competing with their host for the stomach contents (food). A heavy infestation, particularly in a kitten can lead to stunted growth due to malnutrition.
Thin, white with a spaghetti-like appearance; adult roundworms are between 3 – 5 inches long (7.5 – 2.5 cm).
Most cats are asymptomatic to roundworm unless they have a heavy infestation. Kittens may develop a pot-bellied appearance.
Roundworms can sometimes be present in your cat’s vomit or stool. Eggs pass out of the body via the stool, which is how they go on to infect their next host. Eggs are too small to be seen but can be viewed by your veterinarian using a microscope.
Infection with roundworm occurs while the kitten is in-utero. Encysted roundworm larvae live in a dormant state in the tissues of the cat; they are not able to be killed with worming medication. When the female becomes pregnant, these larvae reactivate and make their way to the queen’s uterus, where they cross the placental barrier and infect unborn kittens. Worms also migrate to the mammary glands and infect kittens during nursing.
Roundworms are easy to treat with an anti-worming medication from your veterinarian.
Tapeworms are a common parasitic worm most transmitted by fleas although cats can become infected with a second type after consuming an infected host (usually a rat). The two most common species of tapeworm to infect cats are dipylidium caninum and taenia taeniaeformis.
Adult tapeworms can grow up to 24 inches (60 cm in length). Once the head attaches to the wall of the intestine with hooks, where it begins to grow a series of proglottids, which of which contains male and female reproductive organs and is capable of fertilising themselves.
Adult tapeworms are long, flat, and made up of a head, neck and multiple segments called proglottids. Once the proglottid segments have reached maturity, they break free and pass out of the cat’s body via the feces or move out of the anus.
Each proglottid is full of fertilised eggs and is capable of movement. They have the appearance of rice, and the pet owner may notice these segments around the fur or the anus of the cat or in the feces.
Once outside the body, the proglottid dries out, revealing the eggs, which look like sesame seeds.
Tapeworms are treated with an anti-worming medication; treat for fleas at the same time. Many topical flea preparations also kill several intestinal worms. For more information on worming and flea medications see, please read our guide to flea and worm treatment pages.
These are not worms obviously, but a lot of people confuse flea larvae with worms when they encounter them. Larvae are the second stage of the flea life cycle. These worm-like larvae can be found in bedding and the environment. They prefer dark places such as in carpet fibres, under furniture and skirting boards.
Flea larvae appearance:
The larvae are a slightly translucent cream colour, often with a dark coloured interior. Larvae can grow up to .25 inch (6mm long). As you can see in the image, the body may also appear black inside; larvae feed on the feces of adult fleas, which contains the blood from their host (your cat). The dark interior of the larvae is the feces/blood meal it has consumed. Due to the worm-like appearance of the larvae, many pet owners will mistake the flea larvae for worms. Worms may be intermingled with dark coloured dirt which is the feces from adult fleas.
What other types of worms can cats get?
Many other types of worms can infect cats including hookworms, heartworm, lungworm, whipworms, stomach worms and bladder-worms. These worms usually stay within the cat, and you will not see worms in the feces or vomit. Worm larvae and eggs will be shed in the feces but are usually too small to see with the naked eye.