Contagious and Infectious Feline Diseases (Part 2)

The Veterinarians’ Guide to Your Cat’s Symptoms: Contagious and Infectious Feline Diseases

Upper Respiratory Infections (URI’s)

The two feline upper respiratory infections that have the most severe symptoms are calicivirus and rhinotrdcheitis. These viruses are included in routine immunizations. Two milder upper respiratory infections, pneumonitis and reovirus are not usually part of a kitten’s or cat’s regular immunization series. Pneumonitis is caused by chlamydia, a bacterialike organism. All four URI’s are highly contagious. Sometimes cats that have recovered from calicivirus or rhinotracheitis become carriers of the diseases and can infect other cats.

Signs of all four URI’s include sneezing, runny eyes and nose. Cats with reovirus will normally present no other symptoms, will not have a fever, and will continue to have an appetite. In general, reovirus requires no medication, but eyedrops are often prescribed, as well as an antibiotic to protect against secondary bacterial infections. Cats with pneumonitis are slightly more ill. Their eyes may require more treatment but they, too, will usually be only mildly feverish and will continue to eat.

Treatment of pneumonitis usually consists of antibiotics and eyedrops or salve. Recovery is usually uneventful. There is a pneumonitis vaccine available through veterinarians. All cats do not need routine pneumonitis prevention, particularly indoor house cats. However, some boarding kennels require proof of vaccination.

Calicivirus infection and rhinotracheitis are more serious. Cats with these diseases run a very high fever and have extremely thick eye and nasal discharges. They may have ulcers or open sores in their mouths.

These, in addition to a diminished sense of smell due to a stuffy nose, will cause a cat to become severely anorexic (as we mentioned in Chapter 1, cat’s appetites are governed by their sense of smell). This can lead to dehydration, causing a cat to become even sicker as her resistance is lowered.

The rhinotracheitis virus may also cause corneal ulcers. These can be painful and cause squinting. They may lead to permanent corneal scarring. Since this disease is caused by a herpes virus, antiherpes eyedrops may be part of the treatment.

There is a syndrome of the calicivirus called the “limping kitten syndrome,” which is characterized by fever and painful, swollen joints. Left untreated, both calicivirus and rhinotracheitis can be fatal, especially in young kittens. These diseases are much more serious than the “common cold.” Older animals will require support and medication for some time, including force-feeding and antibiotics. The likelihood of their survival is good, with proper treatment.

Feline Panleukopenia (also called Feline Distemper) Panleukopenia is a serious viral disease of cats. This virus is highly contagious and is easily transmitted from cat to cat. It can also be carried by humans on their hands, feet, or clothing. This virus also persists in the environment and is difficult to kill with disinfectants. A dilute bleach solution (one part bleach to nine parts water) is the most effective disinfectant.

Panleukopenia is more common in kittens, prior to vaccination, and those with poor immune systems, although it can occur in adult cats if their immunity fails and they are exposed to an especially virulent strain of the disease. A kitten or cat with panleukopenia will be very sick. She will have gastrointestinal symptoms, including severe diarrhea, dehydration, high fever, severe depression (see definition), and vomiting. In addition, her bone marrow will be profoundly depressed, the first sign of which is a severe lowering of the white blood cell count.

The word “panleukopenia” means depression of all the different kinds of white blood cells. The combination of a disruption of these two different body systems will cause serious problems. When a cat’s gastrointestinal system is damaged by a viral infection it allows bacterial invasion of the body via the bloodstream. Normally, white blood cells eat (phagocytize) the bacteria as they enter the bloodstream. But if the white blood cells are depressed, the bacterial infection can become systemic, leading to septicemia (bacterial infection of the bloodstream). This is the primary cause of death in cats with untreated panleukopenia, although they would probably eventually die from the dehydration caused by vomiting and diarrhea.

Treatment consists of intravenous fluids to rehydrate the cat and control water balance, some supplemental nourishment, and antibiotics. Adult cats that have prompt treatment usually recover. Young kittens have a high mortality rate from panleukopenia, even with treatment.

Routine vaccination against this disease is effective and extremely important. For kittens’vaccination schedule for adults’.

Fungal Feline Diseases

In addition to ringworm (see below), there are several other feline fungal diseases. Cats, however, are less apt to be infected with a fungal disease than dogs.

Aspergillosis is a fungus that usually attacks the respiratory tract of cats and may infect the nose. It is found in the air, the soil, moldy animal feeds, and decaying hay or vegetable matter. Infected animals may have sneezing, nasal discharge, and/or nose bleeds.

There are four mycoses, which are fairly uncommon, but may be serious in a cat. These fungal diseases are usually contracted by inhalation, or possibly through the skin, and then spread to the animal’s internal organs or other tissues. The fungi that cause these diseases usually prefer particular environments and, therefore, are limited to specific geographic locations.

Bldstomycosis is found in the soil in the north-central states, the Ohio- Mississippi River valleys, and the Mid-Atlantic states.

Histoplasmosis is also a soil fungus. It prefers humid, moist soil, and bat, wild-bird, and especially chicken droppings. Histoplasmosis infection is common in the Midwest and East. It is normally characterized by low fever, lethargy, and cough.

Coccidioidomycosis is found in dry, desert areas where the creosote bush grows (central Texas to California), and can affect both cats and humans, but is not contagious.

Of the mycoses, the most common in cats is cryptococcosis, which is found in bird droppings, especially that of pigeons, and in soil contaminated by them. It often attacks the central nervous system. Signs are mostly neurologic, including circling, disorientation, head tilt, seizures, and possible paralysis. Diagnosis is made with specialized tests or biopsy.

Treatment is difficult; the disease is not always responsive to antifungal medication because the drugs are difficult to deliver to the central nervous system. While not normally considered a contagious disease, it has been nicknamed “pigeon handlers’disease.” Therefore, immune-suppressed people should be careful of cats infected with cryptococcosis.

Parasitic Feline Diseases

Many of the parasitic diseases that plague dogs are uncommon or nonexistent in cats. Ticks, the principle carriers of many canine parasitic diseases, do not usually adhere to cats, or are immediately removed by grooming. Therefore, diseases such as Ehrlichiosis, Rocky Mountain Spotted Fever, and Lyme disease are very rare in cats.

Heartworm Disease

Formerly considered only a canine disease, heartworm disease can affect outdoor cats, especially in areas that are heavily infested with mosquitoes. The disease is carried by mosquitoes, which bite an infected animal, ingest immature worm larvae, and then deposit the immature worm larvae into another, uninfected animal’s skin and bloodstream.

The infective larvae migrate into a cat’s heart and lungs, after they develop, where they can grow to enormous lengths and, if left untreated, will eventually cause severe heart and lung damage.

In general, cats with heartworms display fewer symptoms than dogs with the disease. Therefore, the disease often goes unnoticed in cats. Symptoms may include breathing difficulty, listlessness, coughing, loss of appetite, and surprisingly, vomiting. Treatment of cats with heartworms is extremely dangerous and requires hospitalization and vigilant monitoring.

The best protection for a cat that is likely to be exposed to a number of mosquitoes is the same preventive oral medication used for dogs. If heartworms are a serious problem in the cat’s environment, the owner should discuss heartworm prevention for cats with a veterinarian.

Diseases That Cats Can Transmit to People (Zoonotic Diseases)

Although most feline diseases are what are called “species specific,” that is, confined only to cats, there are some feline diseases that can be transmitted to people. Rabies, covered above, is the most dangerous. Generally speaking, the best protection against contagion is preventive immunization.

The other important step owners can take to prevent contagion is to pay strict attention to hygiene. Children in particular should be taught to automatically wash their hands after any contact with a cat or her waste, especially before eating, and if they have been playing in an area where cats may deposit waste—sandboxes are particularly attractive to cats. A cat that shares a bed with a person should be kept free from external and internal parasites. Immunocompromised pet owners need to be especially careful to avoid opportunistic zoonotic infections and should discuss ways to prevent transmission with both their veterinarians and personal doctors.

Some of the most common zoonotic diseases associated with cats are:

Cat Scratch Disease (Cat Scratch Fever)

The organism that causes cat scratch disease is a bacterium called Bartonelk henselae. It is a very rare disease but can be transmitted to people by a scratch, bite, and probably by the bite of an infected cat flea.

Cats that transmit the disease are usually in good health. It is a disease that is seen worldwide and most commonly affects children and immune-suppressed people. Occasionally an infected cat will become ill and exhibit swollen lymph nodes and fever.

Signs of the disease in people are tender, swollen lymph nodes and possible fever. The disease is usually treated with antibiotics. The best prevention against cat scratch disease is to maintain very good flea control. Fleas appear to be the most common mode of transmission among cats and possibly to people, too.


Toxoplasmosis is caused by a protozoan organism. It can be spread to people via infected cat feces, contaminated soil or litter, or by eating contaminated or rare meat. The most important concern about this disease is for pregnant women; a fetus infected with toxoplasmosis may develop serious problems. Pregnant women should not handle cat feces, soiled litter, or the sand in sandboxes, and should be sure to wash their hands after gardening or any other contact with soil that could be contaminated. They should also avoid raw meat. The same precautions apply to immunosuppressed individuals. Even though cats are the only species that can pass toxoplasma organisms in their stools, all mammals can be infected. Toxoplasmosis should not be the cause of cat hysteria. It is a rather uncommon problem and even infected cats shed infective oocysts for only a short period. Most people are probably infected by eating raw or undercooked meat and not by contact with cats. Proper litter box cleaning and simple hygiene will normally prevent toxoplasma problems.

A cat can get toxoplasmosis from another, infected cat’s fecal matter, infected soil that can get on her feet and be licked off when grooming, or from eating infected raw meat or prey such as rodents. An infected cat may have lesions on her lungs, liver, gastrointestinal tract, and brain.

The symptoms will vary depending on the organs infected. The brain is commonly affected, seizures and other neurologic signs may develop. Nonapparent infection can also occur in cats.


Ringworm is a fungal skin disease to which cats, dogs, and humans, especially children, are highly susceptible. Children should not be allowed to touch a cat suspected of having the disease. It is primarily spread by direct contact, although spores can be airborne. A cat may carry ringworm fungus without symptoms and act as a source of infection to other pets and people. These “carrier” cats may develop lesions when they are stressed or diseased. However, even after the lesions clear, they main remain infected.

Ringworm lesions on cats are usually patchy, somewhat round, hairless areas, which can also be scaly. These types of lesions should be investigated by a veterinarian. Diagnosis is usually made by fungal culture of infected hairs or examination of infected hairs under a microscope. Some ringworm lesions fluoresce under an ultraviolet light.

Treatment in cats often involves complete shaving of the hair (carefully collecting all the hair in a plastic bag) and treatment with dips and possibly oral medication. The most common oral medicine for ringworm is griseoful vin. This medicine is toxic to and may even kill some cats.


Fleas can and will go from cats to humans given the opportunity. To prevent this from happening, proper treatment of an affected cat and her environment is necessary. See Chapter 2, for more about this.

As we stated in Chapter 2, roundworms (toxocara) can infect people (the condition is known as toxocariasis) and owners must be sure to eradicate roundworms, following a veterinarian’s instructions.