Lethargy is a state of drowsiness, inactivity, or indifference in which there are delayed responses to external stimuli such as sound, sight, or touch. Lethargy may also refer to the general malaise and decreased activity exhibited by animals that do not feel well.

Lethargy is a nonspecific sign associated with many possible underlying systemic disorders. It may have little to no impact on the affected individual; however its presence may represent severe or life-threatening illness. Lethargy of more than a day’s duration should not be ignored, and should be addressed, especially if it persists.

Some causes include anemia, heart or lung disease, infection, trauma, side effects from medications, metabolic disorders or cancer.

Diagnosis and Treatment Notes:

  • Lethargy is typically diagnosed through history and physical examination findings. Determining the cause of the lethargy requires further testing that may include bloodwork, urinalysis, abdominal and chest x-rays, abdominal and chest ultrasound, specialized blood tests, and fecal examinations. In some cases, neurologic examination, CT, MRI or biopsies may also be recommended.
  • Treatment depends on the underlying disorder, severity of the disease, your individual pet, and your veterinarian. Treatment may include fluids, antibiotics, and other medications or surgery to treat the underlying disease. Discuss treatment details when your pet is evaluated and the underlying condition causing the lethargy is diagnosed.


What to Watch for*:

  • General change in demeanor
  • Listlessness
  • Reluctance to play, exercise or perform normal activities
  • Hiding, avoiding contact with people or other pets
  • Decrease in appetite or thirst
  • Gastrointestinal signs (vomiting, diarrhea, weight loss)
  • Difficulty breathing
  • Weakness

* Please notify us if you notice any of the above signs or if you have any questions!