Dog lethargy – what it can mean and when to call a vet

Updated 2026-09-30 · 1 sources

Based on: PDSA

Book a vet visit

This is not usually an emergency on its own – contact your vet if it lasts, gets worse or your dog seems unwell in any other way. Lethargy is a vague symptom that can point towards many different problems.

What to do now

What you can do now

  1. Contact your vet.
  2. Note when it started, how often it happens and what else you see.
  3. Take a photo or short video to show the vet.
  4. Keep fresh water available.
  5. Let your dog rest somewhere calm.

Don't

  • Do not give any human medicine.
  • Do not wait if it gets worse.

What it can mean

Lethargy is a vague symptom that can point towards many different problems.[1] It can be mild, serious or, in some circumstances, come and go.[1] Possible causes include infections, obesity, pain, heart disease, anaemia, kidney disease, liver disease, hormone problems, certain medicines and poisons.[1]

Possible causes

  • Infections
  • Obesity
  • Pain
  • Heart disease
  • Anaemia (low red blood cell numbers)
  • Kidney disease
  • Liver disease
  • Hormone problems
  • Certain medicines
  • Poisons

What the experts say

“Infections ; Obesity ; Pain ; Heart disease ; Anaemia (low numbers of red blood cells) ; Kidney disease ; Liver disease ; Hormone problems ; Certain medicines ; Poisons”

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

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Common questions

What does lethargy mean in a dog?

Lethargy means being low in energy.[1]

Can lethargy be serious?

Lethargy can be mild, serious or, in some circumstances, come and go.[1]

What can cause low energy in dogs?

Possible causes include infections, obesity, pain, heart disease, anaemia, kidney disease, liver disease, hormone problems, certain medicines and poisons.[1]

Sources

  1. PDSA

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages

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Other symptoms in dogs

LumpsMouth PainNystagmusOver-groomingRed or swollen eyesRed, inflamed or sore skinReduced AppetiteReverse SneezingRunny EyesScootingSeizuresSneezing