12 Underlying Reasons for Lethargic Cats

Updated April 4, 2018
Sleepy kitten

While cats can normally sleep as much as 16 hours each day, a lethargic cat is a cause for concern. There are many underlying medical issues that can lead to a general sense of lethargy in a cat.

Symptoms of a Lethargic Cat

It's important to recognize lethargy compared to the normal sleep behavior of a cat. Cats should be able to wake easily and have active periods during the day. Some symptoms you should look for include:

  • A listless or drowsy disposition when awake
  • A marked decrease in normal active behavior like playing, roaming, and grooming
  • Lack of appetite and weight loss as well as diarrhea and vomiting
  • Weak physical movements and possibly tremors
  • Unusual shyness and hiding
  • Fever and breathing problems
  • An overall difference in how your cat behaves

Illness and Lethargy in Cats

There is no single specific illness that results in lethargy exclusively. Rather, it's a symptom indicating a possible medical disorder.

Anemia and Blood Disorders

Anemia is a severe depletion of red blood cells. It can have several causes including parasites, infectious diseases, toxin exposure and cancer. Anemic cats may need to have one or more blood transfusions while the underlying cause is treated.

Arthritis, Inflammation, Pain and Trauma

Cats with arthritis and other muscular-skeletal trauma and inflammation will become lethargic if their pain level is high enough. Your veterinarian can prescribe pain relievers such as Tramadol, a type of steroid called prednisone, and possibly some alternative therapies like acupuncture, massage, and heat packs.


Cats who have trouble breathing due to asthma will understandably become lethargic. Asthma is typically treated with prednisone or Depo-Medrol.


Many types of cancer include lethargy among their symptom list. Treatment will depend on the type of cancer but may include chemotherapy and surgical removal of tumors.

Cardiovascular and Pulmonary Disorders

Disorders of the heart and lungs make it harder for a cat to breathe and effectively pump blood to the rest of the body which results in lethargy. Your veterinarian may prescribe medications to treat.


Lethargy is a symptom of cats with ketoacidosis, which occurs in advanced cases of diabetes. If your cat has diabetes and becomes extremely lethargic, take him or her to the veterinarian immediately as this requires treatment right away. Diabetes is treated with insulin and special medical diets.

Endocrine and Metabolic Disorders

Disorders of the endocrine system, such as hypothyroidism, can lead to lethargy. Veterinary treatments used for these conditions include lifelong medication, surgery to remove affected glands, and special veterinary diets.

Gastrointestinal Disorders

There are several disorders of the gastrointestinal system where lethargy will be one of the observed symptoms. A veterinarian who suspects your cat is suffering a stomach disorder will do a full markup of tests including blood work, X-rays, ultrasound and even endoscopy and biopsies. Once the type of disease is diagnosed, treatment can include special veterinary diets and medication.

Infections (UTI) and Disease

Various diseases that affect the eyes, skin, kidneys and urinary tract can cause lethargy. Immune and infectious diseases can be possible causes as well.

Neurologic and Neuromuscular Disorders

Cats with disorders affecting their nervous system, such as motor neuron disease, feline dysautonomia and neuropathy, will display weakness and lethargy. Treatment depends on the type of disorder but can involve supplements and supportive care if the cat becomes unable to move on its own.


There are many items in your home that are potentially toxic to cats such as house plants, human medications and some types of food. If your cat becomes extremely lethargic suddenly, an emergency veterinary visit may lead to a diagnosis of poisoning. You can also contact the ASPCA National Animal Poison Control Center for advice. A veterinarian may induce vomiting and provide fluids and, depending on the severity, require overnight hospitalization.


During the final phase of rabies, the paralytic phase, cats will become lethargic to the point of unresponsiveness. Unfortunately, there is no cure available for rabies but regular vaccinations can help prevent the deadly disease.

Potential Behavior Problems That Can Cause Feline Lethargy

Cats with lethargy can also be suffering from a behavioral issue rather than, or in conjunction with, a medical cause. Cats with depression are known to become lethargic and show hiding and avoidant behaviors. Any type of cat can suffer from depression although senior cats are particularly at risk. A veterinarian or veterinary behaviorist can help diagnose depression in your cat and prescribe medication and a behavior modification plan to treat this condition.

Consult With Your Vet

Due to all the varying conditions that can cause lethargy, some of which are quite serious, you should take your cat to a veterinarian right away. Your veterinarian will do tests which may include the analysis of blood and urine, X-rays and more. Once the condition is diagnosed, they can proceed with a treatment plan to get your beloved feline friend back on track.

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12 Underlying Reasons for Lethargic Cats