Cat Parasites

No matter what precautions we take, parasites are an annoying fact of life for our pets. In addition to bothersome scratching, parasites can cause infection and diseases that can be dangerous or even deadly. Here are some of the most frequently asked questions about parasites.

What is a parasite?

A parasite is a plant or an animal that lives on or inside another living organism (host). A parasite is dependent on its host and obtains some benefit, such as nutrition, usually at the host’s expense.

Are there different types of parasites?

There are two basic types:

Internal parasites (endoparasites) such as hookworms, roundworms and tapeworms, live inside the body of a plant or animal and produce an infection within the host.
External parasites (ectoparasites) such as fleas, lice, ticks, ear mites and sarcoptic mites, live on the body of the host and produce an infestation.

  1. How dangerous are parasites to my pet?

    It depends on the type of parasite, the degree of infection or infestation, and your pet’s reaction to the parasite. For example, a mild flea infestation may be of no consequence to some pets, while others may show hair loss, itching and discomfort. Severe flea infestation may lead to significant skin disease, anaemia or death, especially in young animals. Infestations by ear mites can cause otitis, or inflammation of the external ear, that can be complicated by secondary bacterial infections. Pets may have odour and a crusty brown discharge from their ears. Sarcoptic mites can result in severe itchiness, hair loss and discomfort. These mites also affect humans who acquire them from contact with affected animals.
  2. Are parasites a danger to my family?

    Although animals may be affected by a diverse group of parasites, most of them affect only animals and pose no risk for humans. There are a few parasites which pet owners should be aware of, not only because of the illness they cause in animals, but because they may also cause human disease. Diseases transmitted from animals to humans are called zoonotic diseases. Ingestion of roundworm eggs from soil can cause blindness, nervous system damage, or damage to internal organs. Hookworm infection may result in red tortuous skin lesions, and Sarcoptes mites cause an itchy red rash. Your veterinarian can recommend methods to prevent, treat or control many canine parasites to reduce the chance of human exposure and to keep your pet healthy.


Internal parasites:


What you should know about worms

Just because worms live inside your pets body and are not visible to you does not mean that they can be ignored. In fact severe worm infestations can result in anaemia, intestinal obstruction and even death.

Pets most often affected

All breeds and ages of pets can be affected but the younger animals are generally more severely affected by these internal parasites.

Roundworms (Ascarids)

Roundworms, often called "ascarids", are the most common parasite of the digestive tract in dogs and cats.

How do roundworms cause disease in pets?

In your pet’s intestines, roundworms absorb nutrients, interfere with digestion and can damage the lining of the gut. Animals with mild infestations of roundworms may not show any signs of disease. Animals with more severe infestations may be thin, have dull hair coats and develop a pot-bellied appearance. Some may become anaemic and show symptoms like vomiting, diarrhoea or constipation. Rarely, in severe infestations, the roundworms can cause obstruction of the intestines. A cough may be observed in some animals due to the migration of the worm larvae through the respiratory system. In young animals the migration of the larvae in the lungs can cause pneumonia. Adult worms may be seen in the faeces or vomit. The worms are round on cross-section (hence the common name) and look a bit like spaghetti.

Are roundworms of any danger to people?

Accidental ingestion of roundworm eggs by people may cause blindness, nervous system damage or damage to internal organs.



Hookworms (Ancylostoma) are one of the most common intestinal parasites of dogs and cats (especially puppies and kittens), and can cause severe disease including anaemia and serious diarrhoea. Hookworms have either teeth-like structures or cutting plates with which they attach themselves to the wall of the intestine and feed on the animal’s blood. The mucous membranes e.g., gums will appear pale, the animal will become weak, and sometimes black, tarry stools can be seen. Growth in young animals is stunted, and the hair coat may appear dull and dry. Animals may become emaciated and eventually die from the infection.

Are hookworms of any danger to people?

Hookworm larvae can penetrate the surface of a person’s skin (usually through bare feet) and migrate through it, causing a disease called "cutaneous larva migrans" or "creeping eruption". The lesions appear as red lines under the skin and sometimes break open at the skin’s surface. These lesions cause severe itching. Usually the larvae will die in several weeks and the condition will disappear. In severe cases the larvae may make their way through the skin and enter deeper tissues. This may cause lung disease and painful muscles.



In heavy infections, we may notice abdominal discomfort or nervousness in the animal. The animal may vomit and sometimes have convulsions. It is thought that the convulsions are due to toxins produced by the tapeworm. The active tapeworm segments around the anal area may cause an animal to lick or "scoot" on the floor, because of the itchy feeling around the anal area. Scooting may also be as a result of inflamed anal sacs, which can be expressed by your veterinarian.

Are tapeworms of any danger to people?

Accidental ingestion of certain tapeworm eggs may result in cysts forming in the skin, brain, muscle etc. Cysts in the brain can for example lead to epilepsy.

What can be done to reduce the risk of a worm infection?

Regular deworming of dogs and cats at strategic intervals reduces the risk of infection and contamination of the environment and thus helps prevent human illness. We recommend beginning deworming at a young age before environmental contamination can occur and continuing at strategic intervals.
Adults should ideally be dewormed once every 3 months whilst puppies and kittens require more regular deworming. Bitches and queens should also be dewormed prior to whelping.


External parasites


What you should know about fleas

Your pet’s scratching could be an early sign of fleas

Pets Most Often Affected

All dogs and cats, from puppies and kittens to seniors

What You Should Know

Adult fleas are small, flat, wingless, and have three pairs of jointed legs. They have siphon-like mouthparts and feed on the blood of their hosts by piercing and sucking. Fleas are just about everywhere – everywhere there are animals – including birds and many mammals.
Dogs and cats are prime hosts, but three of the four stages of the flea’s life cycle are spent away from the host. The life-cycle stages are egg, larva, pupa and adult. Under optimal conditions, the life cycle averages about 28 days. When conditions are not favourable, the life cycle can be longer. Because fleas prosper in warm, humid environments, temperature and humidity changes can affect the length and success of their life cycles. The adult flea spends all of its time on a host, and this is the life-cycle stage pet owners usually encounter.

It is not true that adult fleas hop from the host animal back to the environment and then to another host. A flea can survive only a few days if it is taken off the host and left in the environment.

In suitable environments, fleas can breed indoors all year. Fleas on dogs and cats can result in obvious irritation and itching. But they can also trigger a variety of more serious allergic reactions, including dermatitis – an inflammation of the skin. Fleas can also transmit tapeworms. Because fleas feed on blood, blood loss can result in anaemia, with puppies at particular risk.

Scratching or excessive licking may be the first sign that your pet has a problem with fleas. This scratching can lead to hair loss and skin infections. Look for irritated areas on your pet’s back, abdomen, neck, rump (especially the tail base) and on the inside of the thighs. If you think your pet has fleas, see your veterinarian.



  • Scratching
  • Hair loss
  • Unusual amount of chewing and licking
  • Black specks on pet’s skin and coat

What You Can Do to Help

Your veterinarian can recommend a preventive treatment

How long will it take to get rid of my pet’s flea infestation?

It’s important to realize that the fleas you see on your dog are only a small percent of the entire flea population. Fleas lay eggs that fall off your dog into your home or where your dog lives or sleeps. These eggs hatch and become flea larvae that spin cocoons and become pupae. These pupae will eventually develop into pre-emerged adult fleas and remain in their cocoons until stimulated to emerge by the presence of a host. Only 5% of the flea population exists as adult fleas; the remainder is immature flea stages that are too small for you to see. Flea eggs make up 50%, while flea larvae make up 35% and pupae 10%.
Topical treatment kills adult fleas and prevents flea eggs from hatching, so once you apply it any adult fleas will be killed and flea reproduction will stop. Remember, however that the fleas you see on your dog are only 5% of the problem. In order for your flea infestation to be resolved, all of the immature stages in your pet’s environment must become adult fleas that are then killed by contact with your dog. This may take several months, depending on the degree of your flea infestation and the temperature (which affects the length of the flea life cycle). This means that you can expect to see a greater than 90% control of your flea infestation during the first month but because adult fleas will emerge from cocoons in your environment, you may see a few fleas for several months until the flea population is destroyed. So you may need a little patience; and don’t be concerned about seeing small numbers of adult fleas on your dog while you are destroying the flea population. When the environmental flea population has been destroyed, the problem will end, but keep treating to prevent a new flea infestation from beginning.

Are flea bites harmful or just annoying?

Dogs differ in their response to flea bites. When fleas bite, they deposit flea saliva into the skin, which acts as an anticoagulant so that they can feed easily. The flea saliva which contains foreign proteins, can cause an allergic reaction resulting in flea allergy dermatitis, also known as flea-bite hypersensitivity, which causes the skin to become inflamed and lose hair. Secondary bacterial infections may also complicate the underlying flea allergy. Dogs with flea-bite hypersensitivity commonly are itchy and frequently have hair loss at the base of the tail, extending up the back. Just as certain people are allergic to bee stings and others not, so are certain pets more sensitive to flea bite saliva than are others. Dogs sensitive to flea bites may be very uncomfortable due to their flea exposure, while less-sensitive dogs may be unaffected by them. With hypersensitive pets, it only takes one or two fleas to set off a nasty reaction. When flea infestations are severe and blood loss is high from feeding, serious illness may result, especially in kittens. Severe anaemia and death may result from severe flea infestations. Products such as Revolution (Reg.No.: G2819 & G2820, Act 36 1947) will effectively prevent the establishment of fleas and control flea infestation following application. Use of Revolution will ensure that treated animals will be free of flea infestation. In clinical trials Revolution was shown to improve the clinical signs associated with flea allergy dermatitis as a direct result of eliminating fleas from the animals and their environment.


Ear Mites

These troublesome pests are unpleasant for pet and owner alike.

Pets Most Often Affected

Ear mites affect both dogs and cats of any age, although they seem to be involved more frequently in feline ear infections. However, they can still be a problem for dogs and can be spread from animal to animal and even from dogs to cats. Ear mites feed on the lining of the ear and cause inflammation, redness and discomfort. Dogs may rub or scratch their ears and you may even notice mild hair loss or scratches at the base of the ears. Dogs and cats may shake their heads and scratch so vigorously due to the irritation the mites cause that it results in ruptured blood vessels within the ear flap. A bloodsac or otheamatoma forms within the ear flap which then needs surgical intervention. Bacterial infections may also result from the damage to the ears caused by the mites. Topical treatment is also highly effective against the parasite that causes ear mites (Otodectes cynotis). Some animals may harbour mites, but have no clinical signs of infestation, therefore, all animals within a household should be treated, not just the visibly affected dog.

What You Should Know

Ear mites are highly contagious and pass easily from pet to pet. Otodectes cynotis, the ear mite of dogs, accounts for 5 – 10 percent of otitis externa cases in dogs and even more so in cats. Otitis externa, an inflammation of the external ear, results in frequent head shaking and pawing, an unpleasant odour, and discharge.
Ear mites are easily transmitted among animals and are spread by direct contact. These troublesome pests do not burrow in the ear; rather, they live on the ear’s surface.


  • Ear infection
  • Intense scratching or head shaking
  • Red-brown or waxy ear discharge that look like coffee grounds
  • Itching skin around ears, head, neck
  • Thick crust around outer ear
  • Possible crust and scales on neck, rump, and tail

What You Can Do to Help

Your veterinarian can recommend a preventive and/or therapeutic treatment


Sarcoptic Mange (scabies)

Scabies is the name of the disease caused by the mite Sarcoptes scabiei. This is also called “sarcoptic mange.” These mites burrow into the skin and cause intense itching, hair loss and inflammation of the skin. Secondary bacterial infections can also result from the skin’s reaction to the mites. Sarcoptic mites are transmitted from animal to animal by direct contact, and some animals may be carriers of these mites but not show any clinical signs of disease. Sarcoptic mites can also affect humans when they are in direct contact with affected animals.

Pets Most Often Affected

All dogs, from puppies to seniors, occasionally cats.

What You Should Know

Mange, or scabies, is a broad term that describes skin disease. Mange is caused by microscopic mites that lay eggs within a cat’s skin. Scabies mites are round and are so tiny that they are barely visible to the naked eye.
These types of mites tend to prefer the following areas on a cat: the head, ears,neck or generalised over the body. Mange often results in severe skin inflammation, which can trigger intense itching and eventual hair loss. Scratching may cause a secondary bacterial infection in your pet which may require antibiotic therapy. Mange is easily transmitted to other pets and can be transmitted to humans.


  • Intense itching and licking
  • Small red bumps
  • Hair loss
  • Crusty scabs

Your vet will be able to diagnose this mite with the aid of clinical signs, skin scrapings and/or skin biopsies. Mites are however not always evident using these techniques.

What You Can Do to Help

Your veterinarian can recommend preventive treatment


Demodectic mange (Demodex)

Demodectic mange is also called Demodex and is caused by a microscopic, cigar shaped mite called Demodex cati, a parasite which lives in the hair follicles of affected cats. Under the microscope, this mite looks like a little alligator with eight legs. All dogs (and many humans) have a few of these mites on their skin. Demodectic mange most often occurs when the cat has a suppressed immune system, allowing the mites to grow rapidly.

Pets Most Often Affected

Mainly adult cats.

What You Should Know

  • Mites live inside hair follicles -- a difficult place for miticides (chemicals that kill mites) to reach.
  • Physiological stress is an important factor determining the degree of severity of demodectic mange.
  • Sometimes the disease can occur as a result of treatment of the cat with immunosuppressant drugs and also the mites themselves cause suppression of the immune system so the pet needs every advantage to stay healthy.
  • Skin infections are usually present in these cases and antibiotics will likely be necessary.


Hair loss and scaling may be evident on the trunk, underside of the body or may be generalised. Areas of bare skin will be seen. If the disease spreads to many areas of the skin, it becomes generalised demodectic mange.

Your vet will make a diagnosis with the aid of clinical signs, skin scrapings and sometimes skin biopsies.

What You Can Do to Help

Keep your pet parasite-free. Worms are irritants that they need not deal with and fleas may exacerbate the itchiness and skin infection.
Your veterinarian can recommend preventive and/or therapeutic treatment.

* Image courtesy of the Department of Veterinary Tropical Diseases, University of Pretoria .

Disclaimer: Zoetis takes no responsibility for any claims that may arise from information contained in this information sheet. Individual situations may vary from location to location and it is recommended that you consult your veterinarian before any management or treatment decisions are implemented.

Vrywaring: Zoetis neem geen verantwoordelikheid vir enige eise wat mag voortspruit uit inligting vervat in hierdie inligtingsdokument. Individuele situasies varieer van plek tot plek en dit word voorgestel dat u eers u veearts kontak alvorens enige bestuurs- of behandelingsbesluite geïmplementeer word.