4 Neurological Reasons Your Dog is Lethargic

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Lethargy is a condition that can be characterized by unusual fatigue and an overall reduction in motivation. A lethargic dog is either unable or unwilling to get up for almost anything and may seem uninterested in its favorite routines, toys, or even food.

dog lethargic


Why Is My Dog Lethargic?

The problem with looking up “why is my dog lethargic” is that lethargy can indicate such a wide variety of problems, it would be impossible to determine what your dog is suffering from based on this one vague symptom alone.

Things that can make your dog lethargic range from infection and disease to medication and toxicity:


Arthritis, trauma, or even muscle pain can make your dog lethargic. I once adopted out a foster dog that ran away from his new home on the first day. After running the streets for eight days, he found his way back to me and slept for two days straight.


Bacterial, fungal, viral, or parasitic infections can cause lethargy in dogs, like:

  • Parvovirus
  • Distemper
  • Kennel cough
  • Leptospirosis
  • Heartworm disease


A wide range of chronic conditions can render your dog lethargic, including:

  • Heart problems
  • Liver problems
  • Diabetes
  • Hypoglycemia
  • Hypothyroidism
  • Gastroenteritis
  • Electrolyte disturbances


Many veterinary medications can cause lethargy in dogs. However, if you notice your dog lethargic after starting a new medicine or using flea, tick, or heartworm prevention products, call your veterinarian immediately.


Poisonous toads, snake bites, or insect stings can leave your dog lethargic, but so can ingesting human medications and foods that are toxic to dogs, such as ibuprofen or chocolate. If you think your dog has come into contact with anything poisonous or toxic, call your veterinarian immediately.

4 Neurological Reasons Your Dog May Seem Lethargic

In neurology, patients sometimes present with what we refer to as dull mentation, although pet owners may describe it as lethargy. A dog with dull mentation has a decreased level of alertness or consciousness. In addition to sleeping more than usual with drowsiness in between sleep states, your dog will have little to no interest in its environment and slow responses to stimulation, if any at all.

dog laying down

Neurological disorders can affect the brain, spinal cord, and nerves. Dull mentation generally points to a problem in the brain.

Symptoms of brain problems include:

Brain problems that can cause dull mentation and make your dog seem lethargic are:

Brain Tumor

A tumor is an uncontrolled growth of cells within tissue, creating masses that destroy healthy tissue. A tumor in your dog’s brain can result in dull mentation or lethargy.


A stroke occurs when nerve cells and their pathways are deprived of oxygen because blood flow to part of the brain is obstructed or a blood vessel bursts. A stroke can leave your dog with dull mentation or lethargic.

Inflammation of the Brain

Brain inflammation is another potential reason your dog may have dull mentation or seem to be lethargic. It can occur in the brain itself (encephalitis), in the membranes surrounding the brain (meningitis), or a combination of the two (meningoencephalitis).

Another unfortunate symptom of brain inflammation in dogs is pain.


Hydrocephalus is brain swelling due to cerebrospinal fluid (CSF) building up inside the brain. It can be acquired or congenital (present at birth), and certain breeds, like toy breeds, are predisposed.

Hydrocephalus can also cause:

  • Domed skull, soft spot on head (persistent fontanelle), wide set eyes
  • Slow growth, small stature
  • Difficulty learning, eating, drinking, house training

What to Do if You Notice Your Dog Lethargic

Lethargy is a possible symptom of almost every ailment that can affect dogs, so it’s important to look out for any other signs your dog might be showing simultaneously. Because lethargy can indicate anything from a chronic condition to a life-threatening problem, you should contact your vet if you notice your dog lethargic.

However, if your dog doesn’t show any other symptoms, it may be okay to wait a day or two. If your dog’s energy doesn’t improve within this time, or the condition seems to worsen, contact your vet. That being said, if you do notice any other symptoms, you should contact your veterinarian right away.

If your vet suspects a brain problem, you will be referred to a veterinary neurologist for imaging. MRI (Magnetic Resonance Imaging) is often the best way to achieve an accurate diagnosis, determine the severity of the condition, establish treatment options, and predict prognosis.

Southeast Veterinary Neurology Can Help Your Lethargic Dog

While prognosis depends on the underlying cause, there are treatment options for each of the aforementioned brain problems that may cause your dog to seem lethargic or to have dull mentation. With most conditions, the sooner your dog receives treatment, the better the chance of recovery.

Southeast Veterinary Neurology knows this. That’s why we are open for emergencies 24 hours a day. With three convenient South Florida locations in Miami, Boynton Beach ,Jupiter, and Virginia Beach each complete with highly skilled neurology teams and state-of-the-art MRI suites, we are equipped to figure out what is making your dog lethargic. Call any of our locations right now.

treating lethargic dog

Look out for Southeast Veterinary Neurology coming soon to Virginia Beach!