Taken from: http://www.angelfire.com/tn/animacules/cats.html
Panleukopenia-Feline Distemper-This is a disease caused by a virus, but not related to distemper found in dogs or horses. It is harmful to cats of all ages, but especially deadly to kittens. Symptoms to look for include: vomiting and diarrhea, listlessness, loss of appetite, and blood in the stool. Vaccinations are available in combination with vaccines against other diseases. It should be started at 8 weeks of age, followed by boosters at 12 and 16 weeks and then annually. This vaccine is abbreviated FVRCP. The diseases it fights against include: Feline Viral Rhinotracheitis, Feline Calicivirus, Pneumonitis, and Panleukopenia.
Upper Respiratory Infections (URI)-These include the above-mentioned Rhinotracheitis, Calicivirus, and Pneumonitis. These diseases are caused by bacteria and viruses, and they display cold-like symptoms. They are highly contagious. Therefore, cats with URI should be isolated from other cats. URI's could be fatal to kittens if not recognized and treated promptly and properly. The vaccinations do not protect cats against all respiratory viruses and bacteria, but they do protect against the most prevalent strains.
Feline Viral Rhinotracheitis (FVR)- This is caused by a herpesvirus. It affects the upper air passages and lungs. It produces fever, sneezing, coughing, loss of appetite, and eye and nose discharge.
Feline Calicivirus (FCV)- This infection is often contracted at the same time FVR is. It has similar signs, but it mainly affects the lungs and oral cavity, causing viral pneumonia and ulcers to appear on the tongue. Cats can be carriers of this disease for many years.
Pneumonitis-This is an upper respiratory infection that is mainly characterized by eye inflammation. It is caused by the bacteria Chlamydia psittaci.
Feline Leukemia-This disease is caused by a virus that inhibits the immune system and results in various types of cancers and other damaging diseases in cats. It is transmitted from cat to cat by urine, saliva, or other body fluids. It is the number one killer of kittens and is usually fatal in any cat it infects. It acts similar to the HIV virus in humans, by breaking down the immune system and making the animal more susceptible to other diseases and infections. A combination FELV (feline leukemia) and FIV (feline immunodeficiency virus) test can be used to determine whether your cat has been infected or not. A small blood sample is needed for this test, and it must be administered before many veterinarians will begin vaccinations for feline leukemia.
Feline Infectious Peritonitis (FIP)-This disease is caused by a coronavirus. The develpoment of the disease may not occur for months, or even years, after initial infection. Cats are generally affected between the ages of 6 months and 5 years. However, it can occur suddenly in kittens and cause death. Signs include: fever, loss of appetite, depression, and weight loss. There are two forms of this disease, both fatal. The "wet" form causes inflammation of the blood vessels and accumulation of fluid in the chest and abdomen. The "dry" form causes lesions in the lymph nodes, kidneys, eyes, central nervous system, and other organs.
Rabies-Rabies is a fatal disease in many animals. It is transmitted through saliva, so an infected animal could transmit it by biting other animals. All warm-blooded animals are susceptible to this disease. It is caused by a virus and it affects the central nervous system, causing paralysis and death. A positive diagnosis can not be given until the animal is dead, but signs include aggressiveness, paralysis, seizures, and "foaming at the mouth." Vaccines are available as yearly vaccinations or given every 3 years. Kittens should get their first rabies vaccine at 3 months of age.
Heartworm Disease-Heartworms are parasites found in the heart and lungs that can cause serious damage, and even death, in cats. There is a new blood test to see if your cat has been exposed to heartworms, but it only detects exposure and not actual worms. The best thing to do is start your kitten on preventatives right away and keep up with them. They are given in monthly chewable tablets. Signs of heartworm disease in cats include: coughing, vomiting, sluggishness, breathing problems, and actual sudden death. Heartworms are spread by mosquitoes, so all cats are at risk. Presently, heartworm disease is not treatable in cats, so prevention is the key!