Why Is Your Dog Lethargic?

Dogs are typically playful and full of energy and when you notice your dog is less active, you may think that he is ill. You may ask yourself what makes your dog lethargic. There are many factors that cause lethargy: pain, illnesses, aging or anxiety. It is important to identify additional symptoms that may help you detect the problem.


Hypoglycemia is the condition that indicates a lack of sufficient glucose in the dog’s blood. This will make him lethargic. You may also notice additional symptom such as pale gums, shaking or bad breath.


Hypothermia indicates that your dog’s body temperature is below normal. This may be caused by an underlying condition such as shock or hypoglycemia or may be caused by exposure to cold weather. Make sure your pet is always warm and have a thermometer at hand at all times to be able to detect hypothermia or fever.

Acute Stomach Irritation

Acute stomach irritation also known as gastritis may make your dog lethargic. The dog will vomit after meals and will lack appetite also.

Trauma or Injury

Trauma or injuries may make your dog less active. Look out for symptoms such as pale gums, dilated pupils, bleeding, vomiting or visible injuries. 


The ingestion of human medication, toxic materials, toxic plants or rat poison may make your pet lethargic. Poisoning will also be signaled by superficial breathing, vomiting, diarrhea and pale gums.

Chronic Diseases

The above mentioned conditions cause sudden lethargy. If the lethargy occurs gradually and it gets worse, the dog may be suffering from a chronic condition such as:

  • Infections (kidney, bladder infections)
  • Heart disease
  • Internal parasites such as tapeworms, whipworms, hookworms, heartworms
  • Leptospirosis, an infectious disease
  • Canine parvovirus
  • Hypothyroidism or the lack of necessary thyroid hormones
  • Anemia or other blood disorders


If the dog is in pain, he will most likely be lethargic and when he is not left alone he may become unusually aggressive.

The dog may be suffering from pain due to arthritis, dental problems, gum disease, ear infections, eye infections or undetected tumors.


If your pet doesn’t get the necessary nutrients in his diet or gets too little food, he may lack the energy to perform normal activities and he will be lethargic. Talk to your vet to establish if the food your pet eats contains the essential nutrients in the right amounts.

Mental Conditions

Mental conditions such as depression, stress or anxiety may make your pet lethargic. You should identify the problem that causes depression or stress and try to eliminate the problem. The problem may be a chemical imbalance, pain or a change in the dog’s environment.


A bored dog may be lethargic. Make sure to stimulate your pet and offer him entertaining activities and toys. The boredom may easily turn into depression.

Old Age

Lethargy may also be caused by old age; dogs tend to be less active with aging. Aging is also signaled by difficulty to move, joint pain, more sleeping hours or grey hair.