THE MOST COMMON PARASITES IN CATS
How do they affect your cat's health and sometimes your own?
How do they affect your cat's health and sometimes your own?
Roundworms are the most common of the parasitic worms found inside our cats: indeed, a recent UK study found more than a quarter of adult cats are infested with Toxocara cati.1 and infestation rates in kittens are much higher.
Roundworms are highly prolific and females can lay up to 300 000 eggs per day. Infested cats shed these microscopic eggs via their droppings into the environment where they become infective after 2 to 3 weeks. The eggs can stay alive and infective for up to 5 years, being resistant to hot or cold temperature, as well as disinfectants. Cats (and other animals) may swallow those eggs by sniffing or licking soil or other substances soiled by faeces. Cats may also get infested when hunting rodents or other small mammals that can carry roundworm larvae.
Kittens are commonly infested with roundworms soon after birth, as they can be infested via their mother's milk when feeding.
Adult roundworms live in the affected cat's intestines. Many cats do not show any sign of illness, however, cats with a major infestation, especially kittens, may show digestive signs such as a potbelly, diarrhoea and vomiting. They may also show respiratory signs as the immature worms pass through their lungs, typically leading to coughing and pneumonia.
Hookworms are parasites that live in the cat’s digestive system. Recent European studies showed that up to 10% of our cats are infested with these worms, depending on their lifestyle.1,2
The hookworm attaches to the lining of the intestinal wall and feeds on tissue and blood. Its eggs are laid into the cat’s digestive tract and are passed into the environment via the faeces.
Larvae hatch out from the hookworm eggs after about 10 days and live in the soil. They can infest your cat either through penetration of the skin or through swallowing after licking contaminated areas.
Through their feeding activity hookworms cause internal blood loss. They may be a serious threat to cats, especially to kittens as they induce bloody diarrhoea and severe anaemia, which may sometimes lead to death. In older cats the blood loss may be more chronic, and the cat may additionally lose weight.
The “tapeworm” group covers different flat worms that all reside in the small intestine. Dipylidium caninum, the flea tapeworm, is one of the most common as its larvae are hosted by fleas. When a cat swallows infested fleas during grooming, the immature Dipylidium inside the fleas develop into adult tapeworms in the cat’s intestine. Good flea control therefore plays an important role in preventing this tapeworm.
Taenia tapeworms usually affect hunting cats who become infested when they eat small mammals such as mice that host tapeworm larvae.
Echinococcus tapeworms are less commonly found, but can be a problem in certain parts of Europe. Cats become infested when they eat wild rodents harbouring Echinococcus larvae.
Whatever the tapeworm species, infested cats may not show any sign, except perhaps excessive licking of the anal region. This is due to irritation caused by the egg-containing segments as they are being passed. However, heavy tapeworm infestation may cause mild digestive signs such as varying appetite and alternating phases of diarrhoea and constipation.
Lungworms are emerging parasites of cats throughout Europe. Cats may become infested with lungworms when they eat slugs/ snails or prey hosting the larval stage of the worm.
The larvae migrate out of the intestines and reach the lungs via the bloodstream. They develop into adult worms that lay eggs in the cat’s lungs. After hatching, new larvae are coughed up and passed via the faeces. They may then infest birds, rodents or snails.
Some infested cats show no signs of illness, while others show signs of bronchial and pulmonary (lung) disease. Common clinical signs include coughing and sneezing and in rare cases pleural effusion (fluid in the chest). The cat may have difficulty breathing and appear to be lethargic.
Heartworms are not found in the UK or Ireland, but they may be a risk for any cat that travels abroad.
Heartworms are an emerging risk for pets throughout southern and eastern European countries.1 Climate changes are favourable to these parasites as heartworms are transmitted by mosquitoes. Once mature, adult heartworms live in the heart and large blood vessels of the lungs. They can measure up to 30 cm in length.
Heartworm larvae deposited by the feeding mosquito migrate over several months to the heart chambers or into the vessels of the lungs. Once matured, those worms may affect respiratory function and blood flow through the heart and lungs.
Most commonly, cats show no sign of disease. Some of them may nevertheless develop respiratory signs, whereas other cats will suddenly die, without having shown any prior clinical sign. That is why in geographic areas where heartworm is found, cats as well as dogs should be treated preventively against heartworm infestation.
Fleas are a year round problem and the most common external parasites to affect our cats. The adult fleas found on our pets only represent 5% of the flea population. The rest are lurking as eggs, larvae and pupae (cocoons containing pre-emerged fleas) in the environment. This may be outside in the garden, park or woods or may be within our homes – either in carpets, between floorboards, in sofas, or other places our pets like to hang out.
In the environment eggs hatch to larvae and then develop to pupae (cocoons containing pre-emerged fleas). When your cat passes by, this stimulates the young adult fleas to emerge from their cocoons and jump onto your pet. But beware pre-emerged fleas in cocoons can stay alive for 10 months or more!
Fleas are prolific breeders, and flea numbers can explode in the warm spring and summer months when one female flea is able to become 1,000 fleas in just 21 days. But that’s not to say that fleas are only a problem in warmer weather. Milder, wetter winters and heated homes allow these parasites to thrive throughout the year.
You might think you have cleared a flea infestation after treating your pet, only to see new fleas appearing in the days and weeks after administering the treatment. This is actually normal, as flea products do not repel fleas, and re-infestation of your cat is due to the continued emergence of adult fleas from pre-existing cocoons in the environment. As fleas readily survive both indoors and outdoors and because of many possible sources of flea eggs, including wild and feral animals, or just untreated neighbouring cats and dogs, the source of new fleas is a never-ending story.
To really get rid of fleas, you have to disrupt their life cycle – killing fleas before they can start laying eggs, and/or preventing eggs to develop. Regular treatment of your pet will help to control the reservoir of adult and immature stages of the flea lifecycle in your home. But if your house is heavily infested, it is recommended to use a home environmental spray.
Fleas cause itching and excessive grooming when they bite our cats to feed on blood. Some cats may develop Flea Allergy Dermatitis, an allergic reaction to flea saliva resulting in intense itching, licking, hair loss, and skin thickening which can be very distressing.
Fleas also may transmit tapeworm and diseases such as feline infectious anaemia. Kittens can become anaemic due to the amount of blood sucked out by fleas when feeding - as their bodies are so small they are unable to tolerate this amount of blood loss.
Ticks are external parasites that are able to infest cats. They are most abundant from spring to autumn but can be active all year round. Because of climate change, increase in deer populations (which host ticks) and travelling pets, ticks remain active for longer periods, their numbers are increasing, and new tick species and tick-borne diseases are appearing where they were previously not present.1,2,3
Ticks are found on vegetation and cling on to our pets as they brush past. It is very difficult to prevent a cat’s exposure to ticks. Ticks can attach to your cat whenever he or she is outdoors, in gardens, woodland or parks.
There are a number of different ticks which can affect our pets; some are more common in different parts of the UK and in other countries so if you travel with your cat please consult your vet about risks in the places you are visiting.
They pierce the cat’s skin and suck blood over several days. This can cause irritation, painful abscesses and anaemia in small animals. Ticks are a particular concern though because they can transmit bacteria such as Anaplasma, Rickettsia and Borrelia, to our pets.