Why is My Dog Lethargic: Listless, Weak, Barely Responsive Dog

One of the most ambiguous and yet extremely important symptoms to watch for in dogs is lethargy.

The quieter your dog gets, the more serious the situation is. 

lethargy [ˈleTHərjē] – lack of energy and enthusiasm; state of sleepiness or deep unresponsiveness and inactivity

Why is My Dog Lethargic: Listless, Overly Tired, Barely Responsive Dog

High urgency, low clarity

Lethargy doesn’t tell you anything about the reason behind it. Anything that will cause your dog to feel unwell can result in lethargy.

While other symptoms might give you SOME indication as to what could be going on, lethargy will tell you NOTHING about the cause.

When your dog becomes severely lethargic, or the lethargy persists for more than a day or two, you do need to see a veterinarian.

Check the vitals

You may notice other symptoms to go with the lethargy, or you may not.

The other day Cookie woke up in the morning quite lethargic. With her, in particular, the change was alarming. The first thing I did was to check her vitals and her gums and look for the presence of other signs. 

Other than the lethargy and disinterest in food, there were none. Everything looked normal. If I had found one more worrisome sign, we’d have been on our way to the emergency clinic. Because Cookie otherwise looked good, we gave her a bit of time to get over whatever was wrong. Fortunately, she improved by the end of the day. If she didn’t, we’d have been on our way to the vet the next morning.

Potential causes

Conditions that can cause lethargy in dogs include the following:

  • Trauma
  • Poisoning
  • Pain
  • Infections
  • Hypoglycemia (low blood sugar)
  • Anemia or other blood disorders
  • Heart disease
  • Respiratory conditions
  • Liver disease
  • Diabetes mellitus
  • Hypothyroidism
  • Addison’s disease
  • Cancer
  • Certain medications
  • Snake bites
  • Parasites
  • Dehydration
  • Hypothermia
  • Gastrointestinal problems
  • Urinary tract problems
  • Electrolyte abnormalities
  • Immune diseases
  • Neurologic and neuromuscular disorders
  • Certain eye diseases
  • Musculoskeletal diseases

I wasn’t kidding when I said that virtually any problem could cause your dog to become lethargic, was I?

Acute versus gradual

Another trap that’s easy to fall into is when changes happen gradually over time. So, for example, when your normally active and playful dog suddenly becomes lethargic, you KNOW something is wrong.

But what if your dog slowly becomes quieter and quieter over time? 

Such gradual changes are easy to miss.

You might think your dog is just slowing down with age. But I have seen senior dogs who could outplay the youngest of them. It is not age that will slow your dog down. It is most likely pain or another medical problem. Please, do always keep that in mind.

When your dog becomes lethargic, he is talking to you.

He says, “I really feel like crap. Please, do something.” It’s the equivalent of a person saying, “I think I should see a doctor.”

Related articles:
Is Severe Lethargy an Emergency?

Further reading:
Dog Weakness and Lethargy: Causes and Treatments

Categories: Lethargy • Symptoms

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Jana Rade edited by Dr. Joanna Paul BSc BVSc

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience. Dr. Joanna Paul BSc BVSc is our wonderful sponsor and has been kind to edit and fact-check my important articles.

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