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Why Is My Dog So Tired? - Lethargy in Dogs

Carla Moreira
By Carla Moreira, Veterinarian. Updated: December 14, 2023
Why Is My Dog So Tired? - Lethargy in Dogs

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As pet owners, we cherish the playful and energetic moments our dogs bring into our lives. However, there may be times when we notice a change in their usual lively demeanor. This may be due to a variety of factors, but one possible explanation is lethargy. Lethargy is a common condition in dogs, and it can be caused by anything from minor issues like poor sleep to serious health problems.

In this AnimalWised article, we will delve into the intricacies of lethargy in dogs, exploring its causes, distinguishing it from tiredness, and shedding light on its potential implications for our beloved pets.

You may also be interested in: My Dog Seems Sad and Tired


  1. What is lethargy in dogs?
  2. What causes lethargy in dogs?
  3. Symptoms of lethargy in dogs
  4. Panting in Dogs: Is it Normal?
  5. What to do if you suspect your dog has lethargy?

What is lethargy in dogs?

Lethargy can be defined as a state of extreme fatigue and sluggishness, where a dog displays a lack of energy and enthusiasm. It is characterized by a significant decrease in activity levels, with the dog appearing unusually tired and uninterested in usual activities.

Lethargy in dogs can indicate various underlying conditions. It is considered a nonspecific sign in veterinary medicine, meaning that it signals a deviation from the dog's usual behavior without providing specific information about the underlying cause.

Lethargy can stem from various causes, spanning from minor factors like a restless night's sleep to more severe health conditions. Regardless of the underlying cause, the manifestations of lethargy often exhibit similar signs and symptoms.

Difference between lethargy and tiredness

Before we dive into discussing what lethargy in dogs is and how to recognize it, let's first make a distinction between two terms: tiredness and lethargy.

Lethargy and tiredness are both states of reduced energy and motivation, but they have some key differences. Lethargy is a more profound and persistent lack of energy and alertness.

On the other hand, tiredness is a more temporary condition that arises from physical or mental exertion, lack of sleep, or a busy day. It is a natural response to activity and can be relieved through rest and adequate sleep. Unlike lethargy, tiredness is typically transient and can be alleviated with proper rest and relaxation.

Keep in mind that puppies, in particular, need a substantial amount of rest, averaging 15 to 20 hours per day, to foster optimal health and development. Similarly, senior dogs may experience heightened fatigue and reduced interest in play due to a decline in bodily efficiency, resulting in lengthened recovery times.

What causes lethargy in dogs?

Lethargy in dogs can be caused by various factors, ranging from benign to more serious underlying conditions. Some common causes of lethargy include:

  • Illness and infections: dogs may become lethargic as a result of various illnesses, such as viral or bacterial infections, gastrointestinal issues, urinary tract infections, or respiratory infections.

  • Pain or discomfort: dogs experiencing pain or discomfort due to injuries, musculoskeletal issues, dental problems, or internal organ abnormalities may exhibit lethargy as a response.

  • Medications: certain medications or treatments, such as chemotherapy or post-surgical recovery, can cause temporary lethargy in dogs.

  • Emotional or behavioral factors: stress, anxiety, or changes in the dog's environment, routine, or social dynamics can contribute to lethargy.

  • Heat or dehydration: dogs can become lethargic when they are overheated or dehydrated, especially during hot weather or after excessive physical activity.

For cases where lethargy persists, becomes severe, or is accompanied by other worrisome symptoms, it is important to seek guidance from a veterinarian for a thorough evaluation and accurate diagnosis.

Do not miss this other article on signs my dog is dehydrated.

Symptoms of lethargy in dogs

To determine if your dog is suffering from lethargy, pay close attention to the following symptoms:

  • Reduced interest in sniffing and scratching: if your dog shows little enthusiasm for exploring their surroundings or engaging in typical behaviors, it could be a sign of fatigue.

  • Occasional whining or whimpering: dogs may vocalize their discomfort or exhaustion through intermittent complaints.

  • Slower movements and a general sense of sluggishness: if your dog's overall pace and energy levels appear slower than usual, it could be an indication of tiredness.

  • Heavier steps and reluctance to move: a tired dog may exhibit reluctance or heaviness in their movements, showing a desire to conserve energy.

  • Excessive panting: while panting is normal after exertion, if your dog is panting excessively even during moments of rest, it may be a sign of fatigue.

  • Restlessness: unsettled behavior, an inability to relax, or constant shifting may be indicative of fatigue.

  • Increased duration of sleep and rest: if your dog is sleeping more than usual or seeking more frequent and extended periods of rest, it could be a sign of tiredness.

  • Frequent pauses during walks: if your dog frequently stops or seems reluctant to continue during walks, it may be an indication that they are experiencing fatigue.

Lethargy, being a nonspecific sign, does not provide a definitive diagnosis. However, it serves as an indication that your dog is experiencing a state of unwellness, prompting the need to reach out to your veterinarian for further assessment. The manifestations of lethargy can differ significantly among individual dogs.

Continue reading our comprehensive article where we provide insights into the signs of pain in dogs.

Why Is My Dog So Tired? - Lethargy in Dogs - Symptoms of lethargy in dogs

Panting in Dogs: Is it Normal?

Dogs commonly engage in panting, particularly on hot days or after physical activity, as a natural means of regulating their body temperature. Unlike humans, dogs possess a limited number of sweat glands, primarily located in their paw pads, which means they rely less on sweating as a cooling mechanism.

Panting serves as a significant form of thermoregulation, a vital physiological process that enables dogs to maintain a balanced body temperature. During exercise, dogs experience an elevation in their metabolic rate, leading to an increased energy demand for various bodily functions. Some of these processes involve muscular exertion, while others generate heat, consequently causing a rise in their overall body temperature.

Efficient thermoregulation plays a crucial role in ensuring optimal biological functioning in dogs. Despite fluctuations in environmental temperatures, dogs possess inherent mechanisms that allow them to manage their body temperature and maintain a relatively stable state.

Why Is My Dog So Tired? - Lethargy in Dogs -

What to do if you suspect your dog has lethargy?

If you notice your dog being unusually tired without any other obvious signs of illness, your vet might recommend waiting for a little while to see if things improve on their own. But if your dog doesn't regain their energy within 24 hours, it's time to take them to the vet for a thorough check-up, including a physical exam and some blood tests. And if your dog's lethargy is persistent and comes with other symptoms like vomiting, it's definitely a red flag that something is not right.

Remember, lethargy itself is not a specific diagnosis. The key is to be aware of your dog's usual energy levels, so you can tell when they're feeling exhausted. When in doubt, it's always better to err on the side of caution and contact your vet.

You might be interested in this other article, where we have listed 30 signs that your dog is sick.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Why Is My Dog So Tired? - Lethargy in Dogs, we recommend you visit our Other health problems category.

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Why Is My Dog So Tired? - Lethargy in Dogs