What this means
Cats naturally sleep a lot, which makes lethargy hard to recognise. What matters is not how many hours your cat sleeps in general but whether it has changed compared with itself. It may greet you at the door less, stop coming to the kitchen when it hears food, lie in the same spot for longer, seek less contact, or stop grooming so that the coat looks untidy and dull.
Cats are very good at hiding illness and pain. In the wild, showing weakness was not safe, so many sick cats simply go quiet, hide away and rest more. For that reason lethargy is sometimes the first and only sign that something is wrong. It is often noticed not at once but only by comparing with how the cat was a week or a month ago. Tiredness is also not a normal part of getting older, and the cause of it is worth finding out.
Only a vet can find the cause of lethargy, after examining the cat and running tests. It helps to know when your cat's behaviour changed, how it is eating, drinking, urinating and passing stools, and whether its weight has dropped. If you can, take a photo or video of how your cat moves and where it rests.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your cat.
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Kidney or other organ disease
When organs slowly work less well, a cat may look tired, eat less, drink more and lose weight. These changes come on slowly, so they are easy to miss.
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A sugar-handling disorder
When the body can no longer keep blood sugar under control, a cat may look tired, drink a lot and lose weight, and the coat becomes unkempt.
About the condition: Diabetes mellitus -
Anaemia
When there are too few red blood cells, or they break down too fast, the tissues get less oxygen. The cat is weak and sleepy, and the gums may turn pale.
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Pain or joint problems
A cat in pain often rests rather than complains. It may lie for longer, avoid jumping and move less, even though it does not seem to be hurting.
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Stools held back
When a cat cannot pass stools for a long time, it may become dull, vomit and eat less. It is worth watching how often it visits the litter box and what the stools look like.
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Cancer or another serious illness
Some illnesses, including cancer of the immune cells, show up as lethargy, a smaller appetite and weight loss before any other sign appears.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- When you first noticed the change and whether it is getting worse
- Whether your cat eats and drinks as usual or its appetite has dropped
- Whether litter-box habits are changing, in how often it urinates and passes stools
- Whether your cat is losing weight or the coat looks untidy
- Whether it hides, avoids being touched or no longer climbs to its favourite places
- Whether it still responds to you as it used to
When to book a routine visit
If your cat has been quieter than usual for a few days, is eating less or has changed its habits, see a vet and do not wait to see whether it passes. Tell the vet when you noticed the change and what else you saw.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Amyloidosis General health A condition in which an abnormal protein, called amyloid, builds up in the organs and slowly disturbs how they work. In cats it can settle in the kidneys, the liver or other organs, so over time these organs can start to work less well.
- Cat flu (upper respiratory infection) Infections An infection of the nose, throat and eyes, caused mainly by two viruses, feline herpesvirus and calicivirus, sometimes together with bacteria. It spreads easily between cats and is especially hard on kittens.
- Diabetes mellitus Hormones and metabolism A condition in which the body can no longer keep the level of sugar in the blood under control, because it makes too little insulin or stops responding to it. Without insulin the cells go hungry while sugar piles up in the blood and spills into the urine.
- Feline immunodeficiency virus (FIV) Infections A virus that slowly weakens a cat's immune system, so the body finds it harder and harder to fight off other infections. An infected cat can look perfectly healthy for a long time, even for years.
- Feline leukaemia virus (FeLV) Infections A virus that spreads between cats through saliva and can cause anaemia and lymphoma and weaken the immune system. Not every infected cat falls ill, but a cat in which the virus takes hold faces serious disease.
- Hip dysplasia Bones and joints The hip joint forms imperfectly, so the ball of the thigh bone does not sit in the socket as it should, and the joint wears over time and starts to hurt.
- Lymphocytic mural folliculitis Skin and coat A skin condition in which immune cells called lymphocytes attack the walls of the hair follicles. The follicles are damaged, the hair falls out, and the skin turns dry and flaky.
- Lymphoma Cancer A cancer that arises from lymphocytes, the white blood cells that defend the body against disease. Because these cells are found throughout the body, lymphoma can affect the gut, the lymph nodes, the chest, the kidneys or other organs.
- Megacolon Digestion and liver A condition in which the large bowel widens and can no longer push stools onward. The stools build up inside it and harden, so the cat cannot pass them for a long time.
- Pancreatitis Digestion and liver Inflammation of the pancreas, a gland beside the stomach and gut. In cats it can show only as a few vague signs, such as listlessness and a lost appetite, so it is easy to miss.
- Feline panleukopenia (feline distemper) Infections A highly contagious viral disease that attacks the gut and the bone marrow, so the number of white blood cells in the blood suddenly drops. It is especially dangerous for kittens and can become life-threatening within a short time.
- Polycystic kidney disease Kidneys and urinary tract An inherited kidney disease in which fluid-filled sacs, called cysts, form in the kidneys. They slowly grow, press on healthy tissue and make it harder for the kidneys to work.
- Pyruvate kinase deficiency Blood and immunity An inherited disease in which the red blood cells lack an enzyme they need to make energy. These cells break down sooner than they should, so the cat can develop anaemia.
- Toxoplasmosis Parasites A disease caused by a single-celled parasite, Toxoplasma. A cat is infected by eating infected prey or raw meat but may show no signs at all, and the parasite matters for people too, especially pregnant women.
Body systems: General health Infections Hormones and metabolism Bones and joints Skin and coat Cancer Digestion and liver Kidneys and urinary tract Blood and immunity Parasites