Common Parasites
in Kittens and Cats

Common Parasites

Cats are not just pets. They are treated like members of the family. And like any member of your family, it’s important to keep your companion animal healthy and free of parasites.


It is fairly common for a cat to become infected with an internal or external parasite at some point in its lifetime. Heartworms, fleas, ticks, and other internal and external parasites are much more than just pests; they can cause life-threatening conditions in your pet—and other health problems that not only affect your cat, but also the safety of you and your family.


We will recommend the best preventive regimen for your pet, based on lifestyle and risk factors. We can also provide expert advice on keeping your whole household safe from parasitic infection. Set up an appointment with us to discuss parasite prevention, or call us to refill your pet’s medication. Protect your pet and your family today!

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Internal and External Parasites


Fleas are the most common external parasite found on cats (and dogs). (Parasites are "freeloaders" that live in or on another creature.) Although fleas are more likely to be a problem during warm-weather months, they can Cat Flea (Ctenocephalides felis)also cause problems during cooler seasons due to their ability to continue their life cycle indoors. How will fleas affect my cat? You will probably first notice the effects of fleas when your cat repeatedly nibbles at and licks its haircoat and skin. On occasion you may actually see tiny brown fleas moving quickly through your cat's haircoat. Cats are very skilled groomers, however, and may remove fleas so well that you do not see them. Your cat's constant nibbling and licking may lead to noticeable patches of hair loss, tiny crusts (called miliary dermatitis by your veterinarian), and reddened, irritated skin. Fleas may also cause skin allergies and can transmit other parasites, such as tapeworms, to your cat.How do I check my cat for fleas?Adult fleas are usually more difficult to find on cats than on dogs. One of the best methods for checking your cat for fleas is to look for flea dirt (actually flea feces) in your cat's haircoat. To check for flea dirt, briskly comb or rub a section of the hair on your cat's back while your cat is sitting or lying on a white piece of paper. If your cat has fleas, black flecks that look like dirt (as a result, we use the term "flea dirt") will fall onto the paper. If you transfer these black flecks to a damp piece of paper, in a short time they will appear red or rust-colored. The red color results because blood sucked from your cat is passed in the flea's waste matter. If the dirt specks do not turn red, then they are probably "regular" dirt.


Coccidia are tiny single-celled parasites that live in the wall of your cat’s (or dog's) intestine. They are found more often in kittens, but they can also infect older cats. Cats become infected by swallowing soil that contains coccidia or other substances in the environment that may contain cat feces. It is also possible that rodents could eat the coccidia and contract a “resting” stage of the parasite. Cats that are old enough to hunt could then be infected when they hunt and eat these animals. Cats are more likely to get infected with coccidia by this method than dogs are. How will coccidia affect my cat? Coccidiosis, the disease caused by coccidia, is usually more serious in kittens but can occur in older cats. The most common sign of coccidiosis is diarrhea. Severe infections, especially in kittens, can kill them.


Heartworms represent an increasingly recognized problem in cats. As in dogs, heartworms are transmitted by feeding mosquitoes and, once mature, end up in the right side of the heart and the large vessels of the lungs. For cats, the likelihood of heartworm infection is directly related to the number of infected dogs in the area. While infection rates in cats (not the typical host for heartworms) are lower than in dogs, studies have shown that up 10-14% of shelter cats are infected. Because mosquitoes can transmit the disease, being an indoor-only cat does not prevent a cat from getting infected. Signs of heartworm infection in cats can vary in severity from asymptomatic to sudden death. How will heartworms affect my cat? The heartworm larvae, which enter the cat’s bloodstream after it is bitten by an infected mosquito, eventually migrate to the heart or blood vessels of the lungs. Here the larvae cause a severe reaction, resulting in lack of oxygen exchange and cough.Signs of infection are variable but most often are related to the respiratory system. A veterinarian may suspect that a cat has been infected in cases of coughing, wheezing, difficulty breathing, vomiting, lethargy or weight loss. While some cats will have very mild signs, others can develop signs of congestive heart failure. Some cats will suffer from sudden death as a result of the death of one or more worms.


Similar to tapeworms and roundworms, hookworms are intestinal parasites that live in the digestive system of your cat (or dog). The hookworm attaches to the lining of the intestinal wall and feeds on your cat’s blood. Its eggs are ejected into the digestive tract and pass into the environment through your cat’s feces.Larvae (young hookworms) that hatch from hookworm eggs live in the soil and can infect your cat directly through the skin or feet and also by being ingested during the cat’s routine licking (cleaning.) How will hookworms affect my cat? Hookworms will cause bleeding into the intestinal tract resulting in internal blood loss. Severe infections can result in death in young kittens. Blood transfusions may be necessary to keep young animals alive long enough for medications that kill the worms to take effect. Adult cats may also suffer blood loss from hookworms and can have diarrhea and show weight loss.If you think your cat is infected with hookworms, call your veterinarian to schedule an appointment for evaluation, diagnosis, and safe, effective treatment.


Almost all cats become infected with them at some time in their lives, usually as kittens. Roundworms may be contracted in different ways, making them easy to spread and hard to control. Your cat may take in (ingest) infective roundworm eggs from the area where it lives or by eating mice or other small animals ("hosts") carrying young worms (larvae). Infection in kittens may also occur through the mother's milk. How will roundworms affect my cat? Adult roundworms live in the cat's intestines. Most cats will not have signs of infection; however, cats with major roundworm infections commonly show vomiting, weight loss, dull hair, and a potbellied appearance. The cat may cough if the roundworms move into the lungs. You may notice adult roundworms in your cat's feces or vomit. They will appear white or light brown in color and may be several inches long.


Ticks are a common pest for animals that are outside for any period of time and are found throughout the United States. Tick species tend to vary in different geographic regions so check with your veterinarian about the common tick in your area. Typically, ticks are most prevalent during the warmer months, with peaks in the spring and fall, but this may vary depending on the tick species in question. Environmental conditions may extend the peak season.Ticks bury their heads in the skin of your cat and gorge themselves on blood, causing mild irritation; however, ticks may also carry several debilitating diseases that pose a serious threat to animals and humans. How will ticks affect my cat? Ticks rarely cause clinical signs unless a disease has been transmitted. Symptoms of infection may include the following:FeverAnemiaLoss of appetiteLethargy or depressionHow do I prevent my cat from getting ticks?Most ticks, approximately the size of a pinhead prior to feeding, are not spotted until they become engorged with your cat’s blood. Regardless of how long the tick has been feeding on your pet, you should remove it immediately with tweezers while wearing gloves. Any contact with the tick’s blood can transmit infection. Ask your veterinarian for proper tick removal methods because simply pulling the tick off of your animal can leave the mouth, head, or other body parts attached to your cat.


Demodex is a parasitic mite that causes a skin disease often referred to as mange. The microscopic Demodex mites live in the hair follicles and oil glands of your cat’s (or dog's) skin or at the skin surface. Cats are also host to a sarcoptic mite called Notoedres. The resulting disease is often referred to as scabies. Although animals often harbor Demodex mites, most healthy animals are able to suppress the populations. How will mange affect my cat? Demodex mites create patches of hair loss that may cause mild irritation and itching. Notedres mites create inflamed areas that are extremely irritated and itchy to the cat. Diagnosis of mites is made through skin scrapings of the affected areas. Most common infestations are found on the head and neck and less commonly on the trunk and limbs.