Educational Articles

Cats + Parasites

  • Atovaquone is given by mouth and is used off-label to treat protozoal infections. Give as directed. Side effects are uncommon but may include stomach upset or skin rash. Do not use in pets that are pregnant. If a negative reaction occurs, contact your veterinarian as soon as possible.

  • Azithromycin is given by mouth or injection and is used on and off-label to treat a variety of infections. Give as directed. Common side effects include stomach upset. Do not use in pets that are sensitive to macrolide antibiotics. If a negative reaction occurs, please call your veterinary office.

  • Capillaria is a small internal parasite, often less than half of a centimeter in length. They are closely related to intestinal worms, though they can live in a variety of locations within the body. Capillaria can affect both dogs and cats, although dogs are more frequently affected. Diagnosis can be difficult because the eggs of Capillaria are shed only on an intermittent basis. While the parasite is easily eliminated with a dewormer, your cat may require additional medications to decrease the inflammation associated with the infection.

  • Cytauxzoonosis is an often-fatal disease caused by a tick-borne protozoan parasite, typically found in bobcats. It is more commonly seen in the southern United States but is spreading with tick migration. It can cause anorexia, lethargy, respiratory difficulty, anemia, and jaundice. Diagnostic testing, treatment options, and preventives are described in this handout. This disease is not transmissible to dogs or humans.

  • Demodicosis is a parasitic skin condition caused by Demodex mites. These microscopic mites can be found on the skin of all animals but, in some cases, they multiply to excessive levels and cause clinical signs. Signs vary depending on the species of mite involved, though generally involve hair loss, skin inflammation, and crusting. Demodex mites found on cats and dogs do not spread to humans.

  • Fluralaner is given by mouth or applied topically and is used to treat flea and tick infestations, and also off-label to treat certain types of mange and mites. Give as directed. Side effects are uncommon but may include stomach upset or neurologic symptoms. Do not use in pets with a history of seizures. If a negative reaction occurs, please call the veterinary office.

  • Heartworms are blood-borne parasites that reside in the heart or adjacent large blood vessels of infected animals. There is no drug approved for treating heartworms in cats and surgical removal is generally the best option. Veterinarians now strongly recommend that all cats receive year-round monthly heartworm preventative in areas where mosquitoes are active all year round. Cats that live in colder areas, where mosquitoes are seasonal, should be given monthly preventives for at least six months of the year.

  • Imidocarb dipropionate is an injectable medication that is administered by a veterinarian to treat babesiosis in dogs. It is also used off-label to treat other protozoal infections in dogs, cats, and horses. Most common side effects include mild drooling, tearing, vomiting, or nasal drip. Do not use in pets with exposure to cholinesterase-inhibiting drugs, pesticides, or chemicals. If a negative reaction occurs, please call your veterinary office.

  • Lung flukes in North America are parasites called Paragonimus kellicotti that infect the lungs of cats after they have eaten an infected crayfish or rodents that have eaten infected crayfish. Eggs are then released by the parasite into the cat’s sputum to be coughed out or swallowed and released in the feces to continue the life cycle. Lung flukes can be found anywhere in North America but more commonly around the Mississippi River and Great Lakes. Infected cats can be symptom-free or may develop cough with sometimes bloody mucus, pneumonia, pneumothorax, lethargy and weakness. Diagnosis can include locating eggs of the parasite from feces or mucus from the lungs. X-rays can also reveal cysts in the lungs caused by the parasite. Treatment requires one of 2 commonly used anti-parasitic medications: Praziquantel or Fenbendazole. Although zoonotic, these parasites won’t transmit directly from cats to humans.

  • Moxidectin and fluralaner are combined in one topical treatment for use in cats. Moxidectin topical is an avermectin antiparasitic that is used to prevent heartworms and treat intestinal parasites (hookworms and roundworms). Fluralaner is used to treat and prevent fleas and also kills black-legged ticks (deer ticks). Give as directed. Side effects are uncommon but may include hair loss at the application site, itching, vomiting, diarrhea, lethargy, excessive drooling, and dry skin. Moxidectin + fluralaner should not be used in pets that are hypersensitive or allergic to it. Do not use this medication in sick, debilitated, or underweight cats. Use caution in cats with known neurologic disorders. If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.