Infectious diseases are those that one animal can pass to another. Vaccines are available to protect your cat from some of them (see Vaccinating Your Cat Against Infectious Diseases), and management of your cat's environment and exposure to other cats can significantly reduce the risk of others. Cats who roam outdoors are at high risk of contracting diseases, as are kittens younger than 16 weeks.
Feline Infectious Peritonitis
Feline infectious peritonitis (FIP) is a potentially fatal disease that appears in two forms. The more common form is effusive (wet) FIP, in which the cat's chest and/or abdomen becomes distended with fluid. This in itself doesn't seem to cause pain, but it can compress the lungs and force fluid into the airways, causing respiratory distress. Other symptoms of effusive FIP include jaundice, mild anemia, enlargement of some lymph nodes, gastrointestinal problems, conjunctivitis and eye ulcers, and neurological impairment. A less common form is noneffusive (dry) FIP, which is more difficult to diagnose because it develops more slowly and symptoms are less specific, usually including depression, weight loss, fever, and anemia. Kidney, liver, ocular, neurological, and pancreatic disease can also occur in cats with dry FIP.
FIP is thought to be caused by mutation of the Feline Enteric Coronavirus (FECV), which causes a common flulike infection of the intestines in cats and most commonly in kittens. The effects of FECV in healthy cats are negligible. But in cats whose immune systems aren't functioning properly, the FECV virus can mutate into the more dangerous FIP form and cause widespread, systemic infection. There is no effective treatment for FIP.
If your cat is diagnosed with a communicable disease, keeping her indoors will not only protect her from additional infection or injury, but will also keep her from spreading the disease to other cats.
FIP is difficult to diagnose not only because the symptoms could indicate other diseases, but also because there is no diagnostic test that distinguishes the FIP virus from other coronaviruses. Some cats carry the virus and shed it in their feces but show no symptoms of the disease. The precise mode of transmission and incubation time are unknown, but infected cats can transmit the disease to other cats. FIP virus may be able to survive at room temperature for up to 3 weeks and may be carried on clothing, shoes, carpets, and other surfaces.
Prevention of FIP isn't easy. Most detergents and disinfectants kill the virus, so keeping litter boxes, food and water bowls, and the rest of the environment clean can help. If you pet or handle cats outside your home, especially outdoor cats or strays, wash yourself and your clothing before they come in contact with your own cat. A vaccine is available for FIP, but veterinarians do not agree on its effectiveness or safety. If you believe your cat is at risk of infection from other cats, speak to your vet about the vaccine and then make an informed decision.
Feline Immunodeficiency Virus
Feline Immunodeficiency Virus (FIV) impairs the immune system, leaving the cat vulnerable to disease and infection. Although affected cats rarely die from FIV itself, they usually succumb to bacterial, fungal, and viral infections. Keeping an FIV-positive cat indoors and away from other cats is essential, both to prevent spreading the disease and to shield the cat from contracting other diseases. Because FIV lowers resistance, its victims usually need to see their vets often. There is no vaccine against FIV.
Unfortunately, several feline diseases have been labeled “like AIDS.” The fact is, you cannot catch AIDS from a cat.
FIV enters the body through open wounds, particularly bites from affected cats, and evolves through three stages. During the acute stage, the cat experiences fever, depression, swollen lymph glands, and often bacterial infections. The latent stage, during which the cat appears well, can last from a few weeks to several years. Finally, the cat enters the chronic stage, becoming highly susceptible to other infections and usually surviving less than 2 years.
Feline Lower Urinary Tract Disease
Feline Lower Urinary Tract Disease (FLUTD) is a common, serious problem in which some part of the urinary tract becomes partially or completely blocked. Formerly known as feline urologic syndrome (FUS), a number of factors acting alone or in combination, including crystals in the urine, bladder stones, urinary tract tumors, bacterial or viral infections, trauma, and congenital malformations can bring on the disease. Sometimes the cause is never identified.
Cats from 1 to 4 years old are most commonly affected, al-though FLUTD can occur at any age. Obesity increases the risk of developing crystals and stones, as do stress, poor-quality or high-magnesium-content foods, inadequate water intake, and improper urine pH balance. Although FLUTD can affect both sexes, the disease is more severe in male cats because their urethras are narrower and more easily blocked than those of females.
FLUTD is painful and potentially life-threatening. If your cat frequently tries to urinate and fails or produces little urine, if there's blood in his urine, or if he's straining or crying when trying to pee or is urinating outside the litter box, he needs immediate veterinary care. Diagnosis of FLUTD can be confirmed with physical examination, x-rays, bloodwork, and/or urinalysis.
Specific treatment for FLUTD depends on the severity of the problem, but the goal is to eliminate the blockage. A special diet designed to dissolve the stones and crystals and clear the urethra often treats mild cases successfully. Intravenous fluids may be given to prevent dehydration and flush the bladder. In severe cases, surgery might be necessary, and your vet might prescribe antibiotics to treat or prevent secondary infection.
Feline Leukemia Virus
Feline leukemia virus (FeLV) suppresses the immune system and is one of the leading causes of serious illness and death in domestic cats. FeLV-positive cats are at high risk of contracting a number of diseases, including not only leukemia but also lymphoma, other cancers, or various bacterial and viral diseases.
You cannot catch leukemia or other diseases from a cat with FeLV. It affects only cats.
FeLV cannot survive in warm, dry environments and is easily neutralized with household soaps, detergents, and disinfectants.
FeLV enters the cat through saliva, blood, mucus, urine, or feces and travels to the lymph tissue. If the cat's immune system is strong enough to destroy the virus, that's the end of the story. If it's not, the virus reproduces and eventually moves to the bone marrow, where it may remain for years without causing serious illness. Ultimately, the virus attacks other tissue and destroys the immune system, leaving the cat vulnerable to disease. Talk to your veterinarian about your cat's risk of contracting FeLV and whether vaccination against the disease makes sense in her case.
There are no clear-cut symptoms of FeLV because the virus itself doesn't make the cat ill but makes it vulnerable to other diseases. If your cat develops chronic behavioral changes or seems to be “not quite right,” take him to the vet.
Upper Respiratory Disease
Viruses and bacteria, acting alone or in combination, cause upper respiratory disease, a common affliction of cats, especially kittens. Let's look at the three most common types:
FHV affects only felines. You cannot get herpes from your cat!
- Feline herpes virus (FHV, previously known as feline rhinotracheitis virus) affects cats differently. Most cats experience rhinitis (runny nose and sneezing), sometimes with conjunctivitis (red, runny, squinty eyes). Occasionally, FHV is more severe, causing diarrhea, fever, and corneal and oral ulcers, especially in kittens. Sometimes antibiotics are prescribed to treat secondary bacterial infection, but the virus has to run its course. FHV is spread through direct contact with a cat who is or has been affected or with mucous from such a cat. A mother cat may also transmit it to her kittens in utero.
- Feline calicivirus (FCV) can cause symptoms like those of FHV as well as fever, joint pain, oral ulcers, and gum disease. There is no cure for the virus, but antibiotics often help manage secondary bacterial infections. A cat may continue to shed the virus and spread it to other cats even after symptoms disappear.
- Chlamydia psittaci is a bacterialike organism that lives in mucous membranes, particularly the conjunctive tissue around the eyes. The most common symptom of chlamydia is conjunctivitis, but it can also cause diarrhea, rhinitis, fever, and pneumonia. Chlamydia infections are usually treated with tetracycline ointment applied to the eyes and other oral and topical antibiotics. People can contract a mild form of chlamydiosis, so wash your hands after handling or treating an affected cat.