Dog Lethargic: When Should You Worry?

A lethargic dog seems unusually tired, slow or uninterested in things they normally enjoy. Every dog has lazy days, especially after a big hike or in hot weather. But lethargy that lasts, or comes with other symptoms, can be a sign of illness. Here is how to tell the difference.

Tired vs. lethargic

• Tired: your dog rests after activity but perks up for food, walks or favorite people
• Lethargic: your dog is sluggish, slow to respond and not interested in things they usually love, even after rest

Common causes of lethargy

• Infection, such as kennel cough or a urinary infection
• Pain from injury, arthritis or dental disease. See signs your dog is in pain.
• Stomach upset, vomiting or diarrhea
• Heat exhaustion after warm weather or exercise
• Vaccine reactions, which are usually mild and short-lived. See vaccine reactions in dogs and cats.
• Toxin exposure, such as medications, plants or chemicals
• Chronic conditions, like heart, kidney or thyroid disease
• Anemia, or low red blood cells
• Depression or stress after a change at home. See can dogs get depressed?

Emergency signs

Go to an emergency vet if your lethargic dog:

• Has pale, white, blue or gray gums
• Is breathing fast or with effort
• Collapses or cannot stand
• Has a swollen belly or is retching
• May have eaten something toxic
• Is vomiting repeatedly or has bloody diarrhea

See pet emergency signs.

What to check at home

• Gum color and moisture. Healthy gums are usually pink and moist.
• Breathing rate at rest
• Eating and drinking
• Peeing and pooping
• Temperature, if you have a pet thermometer. See fever in dogs.

Our guide to checking your pet’s vital signs at home walks you through it.

When to call a vet

Call a vet if lethargy lasts more than a day, keeps coming back or comes with any other symptom, such as not eating, vomiting, coughing or limping. Puppies and senior dogs should be checked sooner. See dog not eating.

What the vet may do

Your vet will examine your dog and may recommend blood work, urine tests or imaging to find the cause. Treatment depends on what they find.

Frequently asked questions

Is it normal for my dog to be lethargic after vaccines?

Mild tiredness for a day or so after vaccines can be normal. Contact a vet if it lasts longer or comes with facial swelling, vomiting or trouble breathing.

Can heat make my dog lethargic?

Yes. Hot weather can make dogs sluggish, but heavy panting, drooling or weakness may mean heatstroke. See summer pet safety.

Is your dog not acting like themselves? Ask a vet

Talk to a licensed vet 24/7, even on holidays, by chat, voice call or video call. Your first month is free with code FREEMONTH, then US $9.99/month, at nyptelevet.com/. One membership covers up to 6 pets, and you can cancel anytime.

Our vets can’t prescribe medication, but they’ll tell you what’s likely needed and when an in-person visit is the next step.

Sources

• Lethargy in Dogs, American Kennel Club
• Lethargy in Dogs: When to Worry, PetMD
• Emergencies in Dogs, VCA Animal Hospitals