An infectious disease is caused by the presence of organisms such as viruses, bacteria, fungi, or parasites (either animalian or protozoan). Most of these diseases can spread from cat to cat via airborne pathogens or through direct or indirect contact. Certain infectious diseases are a concern from a public health standpoint because they are zoonoses (transmittable to humans).
Viral respiratory diseases in cats can be serious, especially in catteries and kennels. Timely vaccination can reduce the risk and severity of an infection. Feline viral rhinotracheitis is the most important of these diseases and is found worldwide. The other important cause of feline respiratory disease is the feline calicivirus.
- Feline viral rhinotracheitis (FVR) is an upper respiratory infection of cats caused by feline herpesvirus 1 (FHV-1), of the family Herpesviridae. It is also known as feline influenza. FVR is very contagious and can cause severe disease, including death from pneumonia in young kittens. All members of the Felidae family are susceptible to FVR,
- Feline calicivirus (FCV)
- Chlamydophila felis
- Feline panleukopenia (FPV) more commonly known as feline distemper is caused by the feline parvovirus, a close relative of canine parvovirus. It is not related to canine distemper. Panleukopenia is primarily spread through contact with an infected cat's bodily fluids, feces, or fleas.
- Feline leukemia virus (FeLV) is a retrovirus transmitted between infected cats when the transfer of saliva or nasal secretions is involved, for example when sharing a feeding dish. If not defeated by the animal’s immune system, the virus can be lethal. The disease is a virus, not a cancer. The name stems from the fact that the first disease associated with the virus was a form of leukemia. By the time it was discovered that the virus was not the same as leukemia, the misnomer had already found its way into the vocabulary of pet owners.
- Feline immunodeficiency virus (FIV), commonly known as Feline AIDS is a lentivirus that affects domesticated house cats worldwide. FeLV and FIV are in the same biological family, and are sometimes mistaken for one another. However, the viruses differ in many ways. Although many of the diseases caused by FeLV and FIV are similar, the specific ways in which they are caused also differs.
- Feline infectious peritonitis (FIP)' is a fatal, incurable disease caused by Feline Infectious Peritonitis Virus (FIPV), which is a mutation of Feline Enteric Coronavirus (FECV/FeCoV). The mutated virus has the ability to invade and grow in certain white blood cells, namely macrophages. The immune system's response causes an intense inflammatory reaction in the containing tissues. This disease is generally fatal. However its incidence rate is roughly 1 in 5000 for households with one or two cats.
- Rabies in cats is a fatal disease transmitted by the bite of an infected mammal, such as a dog, raccoon, bat, or another cat. Animals with rabies suffer deterioration of the brain and tend to behave bizarrely and often aggressively, increasing the chances that they will bite another animal or a person and transmit the disease. Rabies is rare in many developed countries with more than 99% of all human deaths from rabies occurring in Africa, Asia and South America which report thirty thousand deaths annually. In the United States, cats make up 4.6% of reported cases of rabies infected animals.
- H5N1. See: Global spread of H5N1#Felidae (cats)
- Main article: Feline vaccination
- Cytauxzoonosis is a mostly fatal tick-borne disease in domestic cats. It is identified as the blood parasite Cytauxzoon felis.
- Ear mites are mites that live in the ears of animals.
Feline hypertrophic cardiomyopathy
- Heart valve dysplasia
- Luxating patella
- Portosystemic shunt. Found in Persians and Himalayans.
Template:See Cat skin disorders are among the most common health problems in cats. Skin disorders in cats have many causes, and many of the common skin disorders that afflict people have a counterpart in cats. The condition of a cat's skin and coat can also be an important indicator of its general health. Skin disorders of cats vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment.
- Cheyletiella is a mild dermatitis caused by mites of the genus Cheyletiella. It is also known as walking dandruff due to skin scales being carried by the mites. Cheyletiella live on the skin surface of dogs, cats, rabbits, and humans.
- Feline acne
- Feline eosinophilic granuloma
- Flea allergy dermatitis
- Miliary dermatitis (feline eczema)
Tumors and cancer
- Bladder cancer
- Bone cancer
- Intestinal cancer
- Liver cancer
- Lymphoma in animals
- Mammary tumor
- Mast cell tumor
- Nose cancer
- Skin cancer
- Soft tissue sarcoma
- Stomach cancer
- Cerebellar hypoplasia is a disorder found in cats and dogs in which the cerebellum is not completely mature at birth. Cerebellar hypoplasia causes jerky movements, tremors and generally uncoordinated motion. The animal often falls down and has trouble walking. Tremors increase when the animal is excited and subside when at ease.
- A corneal ulcer is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats.
- Epilepsy is characterized by recurrent unprovoked seizures. Epilepsy in cats is rare likely because there is no hereditary component to epilepsy in cats.
- Feline asthma
- Feline Hepatic Lipidosis also known as Feline Fatty Liver Syndrome, is one of the most common forms of liver disease of cats. The disease begins when the cat stops eating from a loss of appetite, forcing the liver to convert body fat into usable energy.
- Feline lower urinary tract disease is a term that is used to cover many problems of the feline urinary tract, including stones and cystitis. The term feline urologic syndrome is an older term which is still sometimes used for this condition. It is a common disease in adult cats, though it can strike in young cats too. It may present as any of a variety of urinary tract problems, and can lead to a complete blockage of the urinary system, which if left untreated is fatal.
- Feline odontoclastic resorptive lesion
- Feline spongiform encephalopathy
- Uterine unicornis a condition in which the female cat is missing a uterine horn. A rare discovery by veterinarians, the condition can be detected by x-ray or ultrasound prior to spaying if the patient has a family history of the medical condition. There is no known scientific study to prove that uterine unicornis is a hereditary genetic disorder. In some cases, the patient may also be missing a kidney on the same side as its missing uterine horn. This phenomenon is also called unilateral renal agenesis.
Detection and disease prevalence
Feline diseases such as FeLV, FIV, and feline heartworm can be detected during a routine visit to a veterinarian. A variety of tests exist that can detect feline illnesses, and with early detection most diseases can be managed effectively.
Researchers at the University of Cornell Feline Health Center believe that "most zoonotic diseases pose minimal threat" to humans. However some humans are particularly at risk. These are people "with immature or weakened immune systems" (infants, the elderly, people undergoing cancer therapy, and individuals with acquired immunodeficiency syndrome).
Some common and preventable forms of zoonosis  are as follows:
Diet and nutrition
Template:SeeTemplate:See also Veterinarians commonly recommend commercial cat foods that are formulated to address the specific nutritional requirements of cats although an increasing number of owners are opting for home-prepared cooked or raw diets.
Although cats are obligate carnivores, vegetarian and vegan cat food are preferred by owners uncomfortable with feeding animal products to their pets. The U.S. Food and Drug Administration Center for Veterinary Medicine has come out against vegetarian cat and dog food for health reasons.
Cats can be selective eaters. Although it is extremely rare for a cat to deliberately starve itself to the point of injury, in obese cats, the sudden loss of weight can cause a fatal condition called Feline Hepatic Lipidosis, a liver dysfunction which causes pathological loss of appetite and reinforces the starvation, which can lead to death within as little as 48 hours.
Pica is a condition in which animals chew or eat unusual things such as fabric, plastic or wool. In cats, this is mostly harmless as they do not digest most of it, but can be fatal or require surgical removal if a large amount of foreign material is ingested (for example, an entire sock). It tends to occur more often in Burmese, Oriental, Siamese and breeds with these in their ancestry.
Food allergy is a non-seasonal disease with skin and/or gastrointestinal disorders. The main complaint is Pruritus, which is usually resistant to treatment by steroidal anti-inflammatory drugs. The exact prevalence of food allergy in cats remains unknown. There is no breed, sex or age predilection, although some breeds are commonly affected. Before the onset of clinical signs, the animals have been fed the offending food components for at least two years, although some animals are less than a year old. In 20 to 30% of the cases, cats have concurrent allergic diseases (atopy / flea-allergic dermatitis). A reliable diagnosis can only be made with dietary elimination-challenge trials. Provocation testing is necessary for the identification of the causative food component(s). Therapy consists of avoiding the offending food component(s). Cats with food allergies constantly itch their red, hairless, and scabby skin. Hair loss usually occurs on the face and/or anus. The most popular prescription diets for cats with food allergies include Hills Science Diet d/d or z/d. It may take, depending on the severity of the reaction, two weeks to three months for a cat to recover if the offending allergen is removed. Immediate results may not be seen.
Malnutrition has been seen in cats fed home-made or vegetarian/vegan diets  produced by owners with good intentions , and most published recipes have been only crudely balanced (by computer) using nutrient averages. Because the palatability, digestibility, and safety of these recipes have not been adequately or scientifically tested, it is difficult to characterize all of these homemade diets. Generally, most formulations contain excessive protein and phosphorus and are deficient in calcium, vitamin E, and microminerals such as copper, zinc, and potassium. Also, the energy density of these diets may be unbalanced relative to the other nutrients. Commonly used meat and carbohydrate ingredients contain more phosphorus than calcium. Homemade feline diets that are not actually deficient in fat or energy usually contain a vegetable oil that cats do not find palatable; therefore, less food is eaten causing a calorie deficiency. Rarely are homemade diets balanced for microminerals or vitamins.  Owner neglect is also a frequent contributing factor in malnutrition.
Cats fed exclusively on raw, freshwater fish can develop a thiamine deficiency. Those fed exclusively on liver may develop vitamin A toxicity.
Non-therapeutic surgical procedures
Spaying and neutering
Dangers in urban environment
- High–rise syndrome
Some houseplants are harmful to cats. For example, the leaves of the Easter Lily can cause permanent and life-threatening kidney damage to cats, and Philodendron are also poisonous to cats. The Cat Fanciers' Association has a full list of plants harmful to cats.
Paracetamol or acetaminophen (trade name Panadol and Tylenol) is extremely toxic to cats, and should not be given to them under any circumstances. Cats lack the necessary glucuronyl transferase enzymes to safely break paracetamol down and minute portions of a normal tablet for humans may prove fatal. Initial symptoms include vomiting, salivation and discolouration of the tongue and gums. After around two days, liver damage is evident, typically giving rise to jaundice. Unlike an overdose in humans, it is rarely liver damage that is the cause of death, instead methaemoglobin formation and the production of Heinz bodies in red blood cells inhibit oxygen transport by the blood, causing asphyxiation. Effective treatment is occasionally possible for small doses, but must be extremely rapid.
Even aspirin, which is sometimes used to treat arthritis in cats, is much more toxic to them than to humans and must be administered cautiously. Similarly, application of minoxidil (Rogaine) to the skin of cats, either accidental or by well-meaning owners attempting to counter loss of fur, has sometimes proved fatal.
In addition to such obvious dangers as insecticides and weed killers, other common household substances that should be used with caution in areas where cats may be exposed to them include mothballs and other naphthalene products, as well as phenol based products often used for cleaning and disinfecting near cats' feeding areas or litter boxes, such as Pine-Sol, Dettol (Lysol), hexachlorophene, etc. which, although they are widely used without problem, have been sometimes seen to be fatal. Ethylene glycol, often used as an automotive antifreeze, is particularly appealing to cats, and as little as a teaspoonful can be fatal. Essential oils are toxic to cats and there have been reported cases of serious illnesses caused by tea tree oil, and tea tree oil-based flea treatments and shampoos.
Many human foods are somewhat toxic to cats; theobromine in chocolate can cause theobromine poisoning, for instance, although few cats will eat chocolate. Toxicity in cats ingesting relatively large amounts of onions or garlic has also been reported.
- Feline Infectious Peritonitis (FIP)
- ASPCA: Pet Care: Cat Care: Feline Infectious Peritonitis
- Rabies vaccine. WHO - Immunization, Vaccines and Biologicals. Retrieved on 2006-04-20.
- Rabies surveillance in the United States during 2006.
- Welcome to Healthypet.com!
- Zoonotic Disease: What Can I Catch From My Cat?
- Vegetarian dogs and cats: Kibble doesn't cut it anymore
- Journal / Book Citation
- John E. Bauer, D.V.M., Ph.D., Dipl. A.C.V.N. (2005-01-01). Nutritional Requirements and Related Diseases. The Merck Veterinary Manual, 9th edition. ISBN 0-911910-50-6. Merck & Co., Inc.. Retrieved on 2006-10-27.
- Plants and Your Cat. The Cat Fanciers' Association, Inc.. Retrieved on 2007-05-15.
- Journal / Book Citation
- Toxic to Cats. Vetinfo4Cats. Retrieved on 2007-01-18.
- Journal / Book Citation
- Minoxidil Warning. ShowCatsOnline.com. Archived from the original on 2007-01-03. Retrieved on 2007-01-18. “Very small amounts of Minoxidil can result [in] serious problems or death”
- Journal / Book Citation
- Antifreeze Warning. The Cat Fanciers' Association, Inc.. Retrieved on 2007-05-15.
- Journal / Book Citation Template:Dead link
- TEA TREE OIL - TOXIC TO CATS
- Be Wary of Aromatherapy Claims for Cats