Lethargy in dogs is often confused with just laziness or extreme tiredness, but that’s not technically correct. It is a symptom of a range of medical conditions, from benign and easy-to-treat conditions to more complex diseases.

In fact, virtually every disease or medical condition in dogs has lethargy as a symptom.


  1. What is Lethargy?
  2. Why Do Dogs Get Lethargic?
  3. Symptoms of Lethargy in Dogs
  4. Why Is My Dog Lethargic All of a Sudden?
  5. Treatment of Lethargy in Dogs
  6. Can You Prevent Dog Lethargy?
  7. How to Boost Your Dog’s Mood & Energy
  8. FAQ

What is Lethargy?

The dictionary describes the word as “the quality or state of being drowsy and dull, listless and unenergetic, or indifferent and lazy,” and it is often a vague sign that something else is going on. This is the case for lethargy in dogs, humans, cats, and other animals, too.

The symptom presents itself as extreme exhaustion and having no energy - to the point where nothing, not even their favorite things, people, or food gets your pooch up and moving.

Why Do Dogs Get Lethargic?

According to research, almost all conditions in dogs will see lethargy as a symptom. It is often one of the first symptoms to arise, much like it is in humans. When we are unwell, we feel tired and lethargic. The same applies to dogs.

Lethargy can arise because of:

Symptoms of Lethargy in Dogs

When your pup is lethargic, they will sleep a lot and be much less active than usual. A fit and healthy dog may greet their owner at the door, but when they feel lethargic, they will barely move from wherever they’re sleeping.

As well as being ‘lazy’, your pup will also appear a little slow. If you call their name, they may take longer to lift their head and acknowledge you, known as ‘delayed response’. In some cases, your pet may not even respond at all.

Lethargy can come as mild or severe cases. By itself, lethargy in dogs will not lead to a correct diagnosis. It can just as easily be a sign of something minor, such as an upset stomach, as it can something very serious, such as late-stage cancer.

Your vet will take all your doggo’s symptoms into account, as well as performing diagnostic testing.

Try to make a note of all your dog’s symptoms to present to your vet. This isn’t always easy, but with a little extra monitoring and/or a Petcube -interactive pet camera, you can watch, rewind-and-playback, and interact with your pet at any time. This will enable you to pick up on problems a lot sooner… and will likely confuddle your furry friend for a few days! (My bonkers bulldog couldn’t figure out where my voice was coming from at first!)

Why Is My Dog Lethargic All of a Sudden?

To a certain extent, lethargy is fairly common for older dogs, just as it is with older humans. Bones start to ache, it’s more difficult to get around, etc. Sudden onset fatigue and lethargy can be a sign of something other than ageing, however. This is more so the case if your pup is just that: a young pup.

If your doggo is lethargic because of a bacterial or viral infection, they will likely have a high temperature as well as sleeping more and avoiding regular enjoyable activities. Arthritis, however, will usually not come with a high temperature or fever and will instead present with stiff and/or swollen joints, and limping.

If your dog is losing weight and lethargic, it could be the case that their diet isn’t quite right. It could also be a sign of something more serious, such as cancer. At the same time, a short-term illness, such as an upset stomach due to eating something out the garbage can, can cause the same symptoms.

Diabetes in dogs causes lethargy as well as obvious weight loss, drinking or eating more, and more frequent urinating. Heart disease can come with all the same symptoms as diabetes, and is also associated with fainting, coughing, swelling of the abdomen, more panting than usual, and a sudden aversion to walks or exercise.

Treatment of Lethargy in Dogs

To successfully treat lethargy in dogs you must get to the root cause of the symptom and then treat it. Sometimes, the condition will require management treatment rather than cure-based treatments.

If your pup is overweight and lethargic, your vet will likely advise that they do a little more exercise and lose a few pounds. A diabetic dog will need another treatment course, however, such as long-term medication, a change in diet, and constant monitoring going forward.

Your vet will come up with a plan that works to treat and/or manage whatever condition they may have. Without your vet, however, you won’t be able to treat your pet at all. The first step is making that chat or booking that appointment!

Can You Prevent Dog Lethargy?

With regular check-ups, a healthy and balanced diet, and the right amount of physical exercise, your dog should be in peak condition. The regular check-ups will be able to pick up on any problems as soon as they arise.

Lethargy cannot be prevented. There’s no way for you to prevent your pup ever bumping into a wall and causing trauma, or getting a urinary tract infection, or getting cancer. Some conditions just happen. An unhealthy lifestyle, a terrible diet, and low levels of exercise, however, will definitely increase the chances of your pooch becoming unwell.

How to Boost Your Dog’s Mood & Energy

One of the easiest ways to boost your dog’s mood and encourage them to get moving a little more is to interact with them. Play games with them, hug them, train them – do all the things you’re supposed to do when you get a dog.

Dogs that get bored are destructive and ill-behaved. Dogs that are stimulated with plenty of attention, training, and toys will be healthier and happier.


My dog is lethargic after shots, is it normal?

Yes, it is normal for a pup to feel slightly unwell for a couple of days after having shots. Your vet will be able to inform you of all potential side effects, many of which only last for a day or two at most.

Is my puppy lethargic or just sleeping?

A sleeping puppy will usually wake up when you rattle the food bowl, call their name, or interact with them in anyway. A lethargic dog, however, will not. They won’t be encouraged to move with the things that normally work, such as treats.

Will a dog get lethargic after flea treatment?

Yes, some medications, including flea treatments, can cause your pet to feel lethargic and a little under the weather for a couple of days. Always read the paperwork that comes with flea treatments if you are using at-home versions. Your vet will be able to inform you of any side effects if you have the treatment done there.

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