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Cats + Infectious Diseases

  • Heartworms (Dirofilaria immitis) are blood-borne parasites that reside in the heart or nearby large blood vessels of infected animals. Veterinarians now strongly recommend that all cats receive year-round monthly heartworm preventives.

  • 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 heartworm preventative.

  • Feline viral rhinotracheitis (FVR) is an infectious disease caused by feline herpesvirus type-1. It is a major cause of upper respiratory disease in cats and is the most common cause of conjunctivitis. The typical symptoms of FVR involve the nose, throat, and eyes, and include sneezing, nasal congestion, conjunctivitis, excessive blinking, squinting, and discharges from the eyes and nose that range from clear and watery to thick and purulent (containing yellow/green pus). Treatment consists of supportive care, hydration of the environment, and control of secondary bacterial infections with antibiotics and antibiotic eye medications. An effective vaccine exists and is recommended for all cats.

  • Histoplasmosis is an infection caused by histoplasma, a fungus found in moist soils and especially prevalent around the Ohio, Mississippi, Missouri, and St. Lawrence rivers, as well as the southern Great Lakes and Alberta. Fungal spores are inhaled or ingested and cause infection in many sites including the lungs, gastrointestinal tract, eyes, joints, and spleen. This handout outlines signs, diagnosis, treatment, and prognosis. Histoplasmosis is transmissible to humans, especially if they are immunocompromised.

  • Hookworms are intestinal parasites of the cat and dog. Their name is derived from the hook-like mouthparts they use to anchor themselves to the lining of the intestinal wall. They are only about 1/8" (two to three mm) long and so small in diameter that they are barely visible to the naked eye.

  • Idoxuridine is an antiviral topical medication used to treat viral infections of the eye, such as feline herpesvirus-1 in cats. Idoxuridine comes as eye drops or can be compounded by your veterinarian into an eye ointment. Give as directed. Side effects of idoxuridine include eye irritation. Pregnant women should NOT handle this medication.

  • 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.

  • Vaccinations are important to prevent serious illness in cats. Even cats that spend all their time indoors should be vaccinated. Some viruses can be carried into your home on inanimate objects such as shoes and clothing, therefore infecting your cat without her coming into contact with another animal. Your veterinarian is your most important resource in determining what vaccinations you need to give your cat to keep her protected.

  • This handout is designed to give you an overview of some of the internal parasites that can infect your cat. For more detailed information, refer to our separate information sheets on roundworms, hookworms, whipworms, tapeworms and heartworms.

  • In North America, many parasitic lungworms infect cats. Cats can become infected by swallowing infective stages of parasitic lungworm. The exact means of becoming infected varies according to the life cycle of the particular parasite. Signs can include coughing, heavy breathing, wheezing, sneezing, poor appetite or anorexia, weight loss, fever, enlarged lymph nodes, and ocular or nasal discharge, and may be more prominent in kittens due to their immature immune systems. Although the success rate of treatment depends on the severity of symptoms and the number of parasites present, the prognosis for recovery is generally good.