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Why Is My Cat Lethargic?
Written By Alex Olsson
Published: 11/19/2016Updated: 04/02/2025
Veterinary reviewed by Dr. Linda Simon, MVB MRCVS
Lethargy in Cats
As most cat parents know, our pets are naturally inclined to sleep for long hours throughout the day. But when a cat seems excessively tired, uninterested in play, or avoiding food, it may be a sign of an underlying health issue.
If you’re wondering why your cat can’t seem to shirk their sluggish mood, the answer unfortunately isn’t always so straightforward.
Lethargy in cats is a symptom, not a disease, and can indicate anything from a temporary issue like stress to a more serious condition requiring immediate vet care.
Understanding the causes and warning signs can help you determine whether your cat needs medical attention. Read on to find out more about lethargy in cats, symptoms to look out for, and how you can best help your furry friend when they’re feeling lethargic.
Symptoms of lethargy in cats
Lethargy in cats refers to an unusual lack of energy, responsiveness, or movement. While all cats enjoy their naps, lethargy is different. It’s a persistent lack of activity that doesn’t improve with rest. Cats experiencing lethargy may sleep far more than usual, avoid movement, and even appear weak.
It’s often accompanied by other signs that can indicate the root cause of the problem. Some symptoms are mild, while others may suggest more of a medical emergency.
Physical symptoms of lethargy
- Changes in weight (loss or gain)
- Diarrhea
- Fever
- Vomiting
- Thirst/increase in urination
- Jaundice
- Difficulty breathing
- Pain or discomfort
- Dull hair coat/loss of hair
Behavioral changes to watch for
- General inactivity
- Lack of interest or response to surroundings
- Lack of energy
- Sleepiness or drowsiness
- Aggression
When should you be concerned?
Mild lethargy can often resolve on its own if caused by stress or temporary discomfort. But persistent lethargy lasting more than 24-48 hours, especially if combined with vomiting, diarrhea, difficulty breathing, or other severe symptoms, requires immediate vet care.
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Causes of lethargy in cats
Cats sleep a lot by nature, however, excessive sleep or inactivity could be a sign of illness. Rest is your cat's natural response to not feeling well and could be a normal part of recovery from a minor condition or it could be an indicator of a more severe condition.
Non-medical causes of lethargy:
- Sleep patterns – if a cat is sleeping within the normal range and has energy during waking hours, lethargy is unlikely.
- Obesity and poor nutrition – overweight cats often have lower energy levels due to the strain on their joints and heart. A lack of essential nutrients can also cause weakness.
- Stress or anxiety – major changes such as moving homes, introducing a new pet, or loud environments can lead to temporary lethargy.
- Side effects from vaccinations or medication – mild lethargy for a day or two is common after routine vaccines.
Medical conditions that cause lethargy
- Infections and viruses – illnesses like feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), upper respiratory infections, and bacterial infections can cause prolonged fatigue.
- Anemia – a lack of red blood cells due to parasites, chronic disease, or blood loss can lead to persistent lethargy.
- Neurological disorders – conditions affecting the brain or nervous system may cause weakness, disorientation, and lack of movement.
- Liver and/or kidney disease – these conditions lead to toxin buildup in the body, making a cat feel unwell and sluggish.
- Diabetes – high or low blood sugar levels can cause dramatic shifts in energy. Excessive thirst, weight loss, and lethargy are common symptoms.
- Pain and arthritis – joint pain in older cats can discourage movement, leading to lower energy levels.
- Heart disease – poor circulation caused by cardiac issues can result in low energy and difficulty breathing.
Lethargy in kittens: should you be worried?
Kittens naturally sleep for up to 20 hours a day as they grow. But extreme lethargy (where a kitten refuses to play, move, or eat) may indicate a problem.
Signs of a lethargic kitten
- Sleeping much more than usual without periods of activity or movement
- Lack of interest in food or nursing
- Weakness or difficulty standing and walking
- Cold ears and paws, which may indicate illness
Possible causes of lethargy in kittens
- Malnutrition – kittens need frequent feeding to maintain their energy levels.
- Infections and parasites – young kittens are vulnerable to fading kitten syndrome, viral infections, and parasitic infestations.
- Congenital defects – some kittens are born with heart conditions or metabolic disorders that cause lethargy.
Lethargic kittens should always be evaluated by a vet as soon as possible. Kittens are fragile, and any prolonged weakness can quickly become life-threatening to these little ones.
Diagnosis — what to expect at the vet
When you bring your lethargic cat to the vet, they’ll start with a full physical exam to get a better sense of what’s going on. Because lethargy can be a symptom of many different illnesses and conditions, diagnosing the exact cause can take some investigation.
To help narrow things down, your vet will need a complete medical history, including any changes in your cat’s behavior, appetite, or energy levels. Be sure to mention any recent changes in their environment or potential exposures, like a new pet in the house, outdoor adventures, or diet adjustments.
During the exam, your vet will check for injuries, abscesses, swelling, skin issues, or signs of pain that might explain your cat’s lack of energy.
Depending on their findings, they may recommend additional tests, such as:
- Bloodwork and urinalysis – to check red and white blood cell counts, organ function, blood sugar levels, and signs of infection.
- Fecal exam – to screen for parasites that could be affecting digestion and energy levels.
- Ultrasound – to look for abnormalities in organs, tumors, or internal inflammation.
- Chest X-ray – to detect fluid buildup, tumors, or heart issues that could be causing weakness.
- FIV and FeLV testing – to rule out feline immunodeficiency virus and feline leukemia virus.
- Heartworm testing – to check for parasites affecting the heart and lungs.
These tests help your vet piece together the bigger picture and determine the best course of action to get your cat back to feeling their best.
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Treatment for lethargic cats
Treatment of lethargy will depend on the cause identified by your vet. General treatment of lethargy as a symptom often includes an improved diet and supplements. It may also include intravenous fluids or oxygen therapy. Rest is also prescribed for lethargic cats, as well as painkillers if pain is a factor in your pet’s condition.
At-home care for mild cases
- Ensure fresh water is available at all times
- Provide a high-quality, balanced diet
- Keep the environment calm and stress-free
- Encourage gentle activity to maintain mobility
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Vet treatments for serious conditions
- Antibiotics or antivirals – for infections
- Pain medication – for arthritis or injuries
- Iron supplements or deworming – if anemia or parasites are present
- Insulin therapy – for diabetes management
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Recovery: how long until my cat recovers?
Recovery time depends on the cause of lethargy. Mild cases resolve within a few days, while chronic conditions require long-term management. Your pet will likely need follow-up care specific to the medical condition that was the cause of the lethargy.
Preventing lethargy in cats
As a pet parent, there are some steps you can take at home to keep this from happening to your cat:
- Schedule regular vet checkups to detect issues early
- Feed a nutritious diet to support overall health
- Maintain a stress-free environment to prevent anxiety-related lethargy
- Encourage movement and playtime to keep muscles and joints strong
Lethargy Questions and Advice from Veterinary Professionals
cat
8 Years
10 found this helpful
10 found this helpful
My pet has the following symptoms:
High Wbc, Low H&H, Subcutaneous Masses, Lethargy
Our cat has a solid mass in his jaw, cyto sent but unresulted, he's not reacting to injected antibiotics. He has weight loss, not eating/drinking, moving, or using litter box. The vet says it's possible he has FIV. He seems like he's on borrowed time. I'm just unsure if there is anything we could do to get him to recover him or if we should put him to ease.
Feb. 21, 2021
Answered by Dr. Maureen M. DVM
10 Recommendations
Hi,
Sorry about that.
It could be a viral disease if he is not reacting to antibiotics. However, I would encourage you to have a blood test run to confirm if it's indeed FIV. The presence of FIV antibodies is confirmatory.
The problem with viral infections is that there is no known cure. The body's immune system has to fight it off. What the vet offers is medication to relieve symptoms.
Good luck
Feb. 21, 2021
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cat
Three Months
57 found this helpful
57 found this helpful
My pet has the following symptoms:
hi. i have a 3 month old kitten that just all of a sudden stopped eating today, he's ate a few pieces of chicken out of my hand but that is it and he's pretty much laid down all day. i seen him poop once but i haven't seen him drink any water except a few sips of kitten milk i gave him. he is usually running around climbing things and chasing my other cat. I was curious to if he could possibly have FeLV/FIV and all of a sudden be showing symptoms? He hasn't been tested yet.
Dec. 20, 2020
Answered by Dr. Linda S. MVB MRCVS
57 Recommendations
Fiv/felv are two viral diseases that can result in a wide range of symptoms. They wouldn't be the first things I would consider in a young lethargic cat.
I would want to rule out parasites, a toxicity, dietary indiscretion (eating something they shouldn't have) etc.
A vet visit is best. They will examine the kitten and may run a blood test to determine what is going on.
Dec. 20, 2020
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