Overview of Canine Lethargy

Lethargy is a state of drowsiness, inactivity, or indifference in which there are delayed responses to external stimuli such as auditory (sound), visual (sight), or tactile (touch) stimuli. Lethargy may also refer to the general malaise and decreased activity exhibited by dogs 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.

General Causes of Canine Lethargy

  • Anemia (low red blood cell count)
  • Other blood disorders
  • Cardiovascular (heart and vessels) and pulmonary (respiratory) disorders
  • Chronic inflammation or infection
  • Drug or medication related
  • Electrolyte abnormalities
  • Endocrine (hormonal) or metabolic disorders
  • Gastrointestinal diseases
  • Urinary tract disorders
  • Cancer
  • Immune diseases
  • Certain severe skin diseases
  • Certain eye diseases, particularly those associated with blindness
  • Neurologic and neuromuscular disorders
  • Nutritional disorders
  • Behavioral disorders
  • Skeletal diseases
  • Infectious diseases
  • Exposure to certain toxins
  • Physical trauma
  • What to Watch For

  • A general change in demeanor
  • Listlessness
  • Reluctance to play, exercise or perform normal behaviors
  • Hiding, avoiding contact with people or other pets
  • Decrease in appetite or thirst
  • Gastrointestinal signs (vomiting, diarrhea, weight loss)
  • Difficulty breathing
  • Tremors
  • Weakness
  • Changes in the level of consciousness
  • Fever
  • Diagnosis of Lethargy in Dogs

    As lethargy is a very nonspecific sign and is associated with dozens of physical ailments, baseline laboratory tests are useful in identifying any systemic abnormalities that should be pursued with further testing. Examples of these baseline screening tests include: 

  • Complete blood count (CBC)
  • Biochemical profile
  • Urinalysis
  • Fecal examination
  • Chest and abdominal radiographs (X-rays)

    If baseline tests are inconclusive or if abnormalities are detected, your veterinarian may consider doing additional diagnostic tests, such as:

  • Abdominal or thoracic/cardiac ultrasound
  • Serologic testing for infectious diseases
  • Bacterial culture of the urine, feces or blood
  • Endocrine (hormone) assays
  • X-rays of various parts of the skeleton
  • Cytology and biopsy of abnormal fluid or tissues
  • Complete eye examination
  • Complete neurologic examination
  • Complete behavioral assessment
  • Certain immunologic tests
  • Computed Tomography (CT scan)
  • Magnetic resonance imaging (MRI)
  • Treatment of Lethargy in Dogs

    When the underlying problem is unknown, it may be difficult or even impossible to treat lethargy symptomatically. Identifying an underlying cause is essential in determining the appropriate treatment plan and care of the patient.

    Home Care 

    Once therapy has been instituted administer any prescribed medications as directed by your veterinarian. Observe your pet’s general activity and appetite, and notify your veterinarian if any of the symptoms worsen or change.

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