Why Is My Cat Lethargic?

Is your cat lying around more than normal? Do they seem drowsy or “out of it”? Are they not interested in what’s going on around them?

If so, your cat is showing the classic signs of lethargy. Here’s how to tell the difference between a tired cat and a lethargic cat, some possible causes of the lethargy in cats, and what you should do.

What Is Lethargy in Cats?

Lethargy can be defined as an abnormal decrease in a cat’s activity level and alertness. Put simply, lethargy is a cat slowing down when they don’t feel well. In many cases, lethargy is the body’s way of conserving energy to fight off illness or heal from injury.

Lethargic Cat Symptoms

If your cat is lethargic, they may:

• Act more withdrawn
• Not groom themselves as well as normal
• Not walk around or play as much
• Avoid going up or down stairs
• Avoid jumping up into their favorite spot, like onto a cat tree or the back of the couch
• Sleep more than usual

What’s the Difference Between a Lethargic Cat and a Tired Cat?

A lethargic cat can look a lot like a tired cat, but there is an important difference.

Tiredness is a temporary state that resolves with rest or sleep. For example, if you’re up too late, you’ll be tired the next day but will feel fine once you get some extra sleep.

The same isn’t true for lethargy. Lethargic cats often do sleep more than normal, but their lethargy remains unless the underlying problem is addressed.

Is It Normal for a Cat to Be Lethargic?

Technically, lethargy in cats is never normal, but it is sometimes expected.

For example, cats that have just been vaccinated are often lethargic for 24–48 hours. This happens because vaccines make their immune system work harder, which can temporarily cause cats to feel tired, achy, and generally unwell. So, it’s fairly common for a cat to be lethargic after shots.

However, many illnesses will also make a cat lethargic, so it’s likely that a sick cat will be lethargic. Healthy cats do not typically act lethargic. Contact your veterinarian if your cat seems lethargic, as the underlying cause can be serious.

Causes of Lethargy in Cats

Many health conditions can lead to cat lethargy, including:

• Infections: Fighting off bacteria, viruses, or other infectious organisms takes a lot of energy and can lead to a cat acting lethargic.

• Recent vaccination: Cats may be lethargic for a day or two as their immune system responds to vaccination.

• Pain: It’s difficult for a cat to move around or be interested in much of anything if they are in pain.

• Traumatic injuries: Significant trauma leads to pain, and healing requires extra energy.

• Hypoglycemia (low blood sugar): Glucose (a type of sugar) is needed to fuel cells in a cat’s body, especially in the brain.

• Anemia (low red blood cell count): A cat’s body needs the oxygen that red blood cells carry to make energy. Without enough red blood cells, lethargy in cats is likely.

• Heart disease: A heart that isn’t pumping normally can’t move blood around the body well, causing lethargy in cats.

• Respiratory conditions: Anything that hinders the lungs’ ability to move oxygen into the bloodstream can lead to lethargy in cats.

• Liver disease and kidney disease: Waste products build up when these organs fail, which disrupts normal chemical processes and makes cats feel sick and lethargic.

• Hormonal abnormalities (e.g., diabetes): Abnormal hormone levels change physiologic processes throughout the body, which can make cats feel sick.

• Cancer: Different types of cancer affect cats in distinct ways, but lethargy is a common clinical sign across diagnoses.

• Certain medications: Lethargy can be a side effect of certain medications, including some anti-anxiety and pain-relieving medications commonly given to cats.

• Poisoning or envenomation: Common cat toxins and venomous stings or bites can cause pain, damage tissues, and disrupt normal physiologic functions.

• Parasites: Parasites can pass on diseases and directly harm the body, leading to lethargy in cats. For example, fleas may remove so much blood that your cat becomes anemic.

• Dehydration and electrolyte abnormalities: Water and appropriate electrolyte levels are essential for a cat’s body to produce energy and function normally.

• Gastrointestinal problems: Diseases leading to poor digestion or nutrient absorption can reduce a cat’s energy levels.

• Nutritional disorders: Cats can’t be energetic and engaged without good nutrition.

• Lower urinary tract problems: Diseases affecting the bladder and associated structures lead to lethargy, discomfort, and sometimes an inability to urinate.

• Inflammatory or immune diseases: Abnormal immune responses and inflammation can make cats feel unwell and damage the body.

• Neurologic disorders: Disease or injury affecting the neurologic system, especially the brain, can lead to lethargy in cats.

Some of these problems, like cancer, are more common as pets get older, but lethargy can affect cats at any age. Kittens and senior cats tend to have fewer reserves and be a bit more fragile than adults in their prime, so lethargy may develop more quickly or be more severe in the very young or very old.

If your kitten or senior cat becomes lethargic, contact your veterinarian right away.

When Should You Call a Vet About Lethargy in Your Cat?

Call your veterinarian immediately if your cat is extremely lethargic, if your cat is suddenly lethargic, or if their lethargy occurs in combination with other serious symptoms like difficulty breathing or severe vomiting or diarrhea.

Talk to your veterinarian if your cat’s lethargy worsens or fails to improve within a day or two.

Lethargic Cats With Other Symptoms

Lethargy is a very nonspecific clinical sign—it’s seen with almost every health problem a cat could develop. Therefore, veterinarians will often focus on any other symptoms a cat might have when they are trying to figure out what is wrong.

• Lethargic and drooling: Diseases or injuries affecting the mouth are common causes of drooling in cats, and they can cause lethargy too. This includes gum disease, mouth ulcers, or trauma to the jaw.

• Lethargic and vomiting: If your cat is vomiting and lethargic, it could be from problems directly affecting the digestive tract, such as inflammatory bowel disease, or metabolic diseases like diabetes or kidney failure.

• Lethargic and not eating or drinking: Like lethargy, cats that are not eating or drinking well are nonspecific clinical signs that are seen with many diseases. Contact your vet if your cat is lethargic and not eating or drinking for 24 hours.

• Lethargic and losing weight: A poor appetite can lead to weight loss in your cat, but so can diseases such as hyperthyroidism or diabetes, even if your cat is eating well.

• Lethargic and wobbly: Cats who are wobbly could be suffering from a neurologic problem, joint pain, metabolic disease, or they could simply be very weak.

Call your veterinarian if your cat is experiencing any of these symptom combinations.

How Do Vets Treat Lethargic Cats?

Treatment for lethargy in cats is directed at finding and resolving the underlying cause.

To make a diagnosis, your veterinarian will start by taking a thorough health history and performing a complete physical examination. Basic lab work will often be needed as well. This may include:

• Complete blood cell count

• Blood chemistry panel

• Urinalysis

• Fecal examination

• Thyroid hormone levels

• Tests for feline leukemia virus and feline immunodeficiency virus

Recommendations for treatment or additional diagnostic testing will be based on the specifics of your cat’s case and the results of their tests. When the underlying cause is identified and successfully treated, the lethargy should resolve as your cat begins to feel better.

Talk to your veterinarian if your cat’s lethargy does not improve.

Are There Home Remedies for Lethargic Cats?

When your cat acts lethargic, this is a clue that usually means they are not feeling well. It’s important to seek veterinary care for your cat to check for a medical problem.

Changes in your cat’s behavior can be caused by pain, nausea, and underlying disease. Once your vet has determined the underlying cause of your cat’s lethargy, you can speak with your vet about treatments such as medications, supplements, and environmental modifications.

In the meantime, you can speak with your vet about keeping your kitty comfortable and providing supportive care at home, such as:

• Putting cat beds on the floor and providing pet stairs to their favorite places for easier access

• Decreasing stress (using a Feliway® calming pheromone diffuser can help)

• Starting a joint supplement (such as Flexidin®) for stiff joints

• Encouraging better hydration with a hydration supplement (such as Purina® Pro Plan® Hydracare™) and a water fountain