Common feline illnesses: a plain-language guide

A change in your cat can be easy to notice but hard to explain. A thirsty cat, a quiet cat and a cat that is losing weight might each have very different problems. The same illness can also look different from cat to cat. This overview explains the broad meaning of common disease names and the changes that may bring them to a veterinarian’s attention. It cannot identify what is wrong with a particular cat.

Start with the change you have actually seen: meals left unfinished, a different litter-box pattern, a coat that needs more care or a favourite resting place no longer reached. Describe the change without assigning a disease label. The page on noticing signs of illness explains how to make useful notes. An examination, and sometimes tests, are needed before a veterinarian can diagnose a condition and decide how the cat needs to be cared for.

Respiratory infections

The Cornell Feline Health Center’s respiratory infection page describes these infections as common in cats, particularly where cats live close together. Viruses and bacteria are among the possible causes. The upper airways include the nose and throat; an infection there may bring sneezing, eye or nose discharge, coughing and a loss of interest in food. Infections farther down the airways can affect the lungs.

Watch the cat’s whole routine rather than treating a runny nose as an isolated problem. Is the cat eating, resting comfortably and responding as usual? Tell the veterinarian about other cats in the home and any recent arrival. The veterinarian must establish the cause and decide treatment. Breathing with effort, open-mouth breathing or sudden breathing trouble requires immediate veterinary attention, even if the cat’s earlier signs seemed mild.

Feline leukemia virus

Feline leukemia virus, usually shortened to FeLV, is an infection that can affect the blood and the body’s ability to respond to other infections. The Cornell Feline Health Center’s FeLV guide explains that it can spread during close contact between cats, including grooming and bites. An infected mother can also pass it to her kittens. Sharing a home is part of the history a veterinarian needs when considering exposure.

A cat may look well early in the infection. Later concerns can include a falling appetite, weight loss, a poor coat or repeated illness. None establishes FeLV by appearance alone. Blood testing and its interpretation belong to the veterinarian, who may need further testing to clarify a result. Ask what a result means for this cat and for its housemates, and let the veterinarian decide the care plan.

Feline immunodeficiency virus

Feline immunodeficiency virus, or FIV, affects the immune system. The Cornell Feline Health Center’s FIV information says that the virus is mainly passed through bites from infected cats. Quiet, non-aggressive contact is not described as an efficient means of spread. A history of fighting therefore matters when the veterinarian assesses risk; an owner cannot decide infection status from personality or appearance.

Infected cats may have a long period without outward illness. Repeated infections, mouth inflammation, weight loss or a change in behaviour can occur as health problems develop. Testing has limits, and results need veterinary interpretation in light of the cat’s history. A positive result does not describe everything about the cat’s present health. The examining veterinarian decides what further assessment and individual care are needed.

Chronic kidney disease

The kidneys filter blood, make urine and help regulate blood pressure. Chronic kidney disease, often called CKD, means that kidney function is being lost over time. The Cornell Feline Health Center’s kidney disease guide explains this process and the use of blood and urine tests in assessment. Older cats are a particular concern, although an apparently normal routine does not rule out an early problem.

At home, you may see a water bowl emptying faster or larger wet areas in the litter. Appetite can fall, weight can decrease and the coat can look neglected. These signs also occur with other illnesses. Tell the veterinarian what has changed and whether it has been gradual. Only a veterinary examination and appropriate tests can establish the diagnosis; decisions about care must be made for the individual cat.

Hyperthyroidism

Thyroid hormones help control how the body functions. Hyperthyroidism means that too much thyroid hormone is being produced. The Cornell Feline Health Center’s hyperthyroidism page describes it as a common problem of middle-aged and older cats. A cat may lose weight while seeming keen to eat, drink and urinate more, or become unusually active. Vomiting, diarrhoea and a poorly kept coat can also occur.

An older cat becoming restless is not necessarily enjoying a new burst of energy. Look at appetite and body shape alongside activity. A veterinarian checks the cat and uses blood testing to investigate thyroid function, while considering other organs too. The pattern of signs is a reason for that assessment rather than a diagnosis. The veterinarian decides whether hyperthyroidism is present and discusses a suitable treatment plan.

Diabetes

Diabetes involves difficulty producing or responding to insulin, the hormone that helps cells use sugar carried in the blood, as the Cornell Feline Health Center’s diabetes page explains. Owners commonly notice weight loss despite continued interest in food, along with increased thirst and urine output. Body weight and physical activity are relevant parts of the risk discussion.

A cat can appear hungry and still be losing condition. That combination deserves a veterinary visit, rather than an attempt to solve it by changing meals alone. The veterinarian evaluates blood and urine findings alongside the cat’s signs; stress can complicate interpretation of a blood sugar result. Diagnosis and all treatment decisions belong to the veterinarian. Bring observations about food, drinking, litter output and movement so the plan reflects life at home.

Lower urinary tract disease

The lower urinary tract includes the bladder and the urethra, the passage through which urine leaves the body. The Cornell Feline Health Center’s urinary disease page explains that several disorders can affect these structures. Frequent trips to the box, crying while trying to urinate, blood in urine, licking around the genitals or urinating elsewhere are possible signs. Inflammation, stones and obstruction are among the causes a veterinarian considers.

A cat, especially a male cat, straining in the litter box without passing urine needs urgent help: contact a veterinarian or an emergency veterinary clinic now. Do not assume the cat is constipated. For other urinary changes, arrange a veterinary assessment promptly. An examination and urine testing help investigate the cause, and the veterinarian decides treatment. A comfortable box is useful, but cannot rule out or address a blockage.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy, shortened to HCM, is thickening of the muscular walls of the heart. The Cornell Feline Health Center’s heart disease page describes how this can interfere with normal heart function. Some affected cats do not appear ill. Others become lethargic or develop rapid, laboured or open-mouth breathing. Sudden painful weakness or loss of use of the hind legs can occur with a blood clot.

An owner cannot judge heart health from a cat’s willingness to purr or accept a stroke. The veterinarian may use heart imaging and other tests after an examination, including checks for conditions that can cause similar thickening. Only that assessment can establish HCM and guide the care plan. Sudden breathing trouble, collapse or sudden inability to walk normally calls for immediate veterinary contact, rather than watching for a clearer pattern.

Dental disease

Dental disease includes inflammation of the gums, damage to the tissues holding teeth in place and tooth resorption, in which tooth structure breaks down. A cat may hesitate over food, chew with its head turned, drool or have bad breath. Mouth discomfort can also change how a cat responds to handling. Teeth that look fairly ordinary from outside may still need investigation.

Describe what happens at meals to the veterinarian and ask for an oral assessment. Do not force a painful mouth open. The veterinarian examines the mouth and decides whether a more detailed dental evaluation is needed, then determines treatment. The dental health page explains the terms and the observations that can help you discuss them at a visit.

Joint disease

Osteoarthritis is a form of joint disease in which cartilage, the smooth tissue in moving joints, deteriorates. The Merck Veterinary Manual’s joint disorders chapter explains that it can limit movement and be painful, yet cats may conceal the signs. Watch for a change in how your cat reaches a bed, manages steps or moves after rest. A less obvious route through the house can be an important observation.

Stiffness is not a diagnosis, and age does not make discomfort unimportant. The veterinarian examines movement and the joints, considers other causes and decides whether tests are needed. Only the veterinarian can decide treatment. Record activities the cat has stopped doing, rather than asking it to demonstrate a difficult jump. This keeps the discussion focused on the cat’s ordinary life and its current needs.

Cancer warning signs

Cancer is not a single illness with a single outward pattern. The Cornell Feline Health Center’s cancer warning signs page explains that early changes can also point to other conditions. New lumps, unintended weight loss, altered appetite, abnormal discharge or a lasting skin sore are reasons to ask for an examination. Changes in activity, grooming and interaction can be part of the picture too.

A lump is not automatically cancer, and a cat without a lump is not automatically free of illness. Note where a change is, when you noticed it and whether it is changing. Avoid trying to identify it by touch or appearance alone. The veterinarian decides what investigation is needed to establish the cause and what treatment, if any, is appropriate for the cat.

Heartworm and wider care

Heartworm is passed by mosquitoes and can affect a cat’s lungs, including when worms have not reached adulthood. Coughing, breathing trouble, vomiting or a loss of appetite can occur, but other diseases can look similar. The heartworm myths page explains why indoor living and a reassuring test result do not settle every question. Diagnosis and care still require an examining veterinarian.

This overview also leaves room for routine care. The vaccine questions page explains how a veterinarian considers exposure and lifestyle. When arranging a visit, bring the changes you have noticed rather than choosing a disease from a list. That helps the conversation begin with your cat and allows the veterinarian to decide what needs checking.