Why is My Dog Acting Lethargic?

There are many reasons that your dog might be acting lethargic. Some of them are not worth worrying too much about, while others are serious medical conditions that require an emergency trip to the vet. You need to know enough about these possible reasons for dog lethargy to be able to decide when your pet needs to see the vet for immediate care.

Lethargy is rarely normal in dogs, and your pet will appreciate that you know enough about the condition to recognize when they are experiencing a medical emergency. Knowing more about this condition can help you to attend to your pet’s needs when an emergency occurs.

dog lethargy

What is Lethargy?

Lethargy is not just acting sleepy. Lethargy is an extreme tiredness or an unwillingness to get up and move around. Some pets will also seem weak or stumble around when they do move. Pets with lethargy will also seem depressed and might seem like nothing makes them alert or interested in things.

Lethargy is usually quite recognizable, and most pet owners can tell that something is wrong with their pet who is displaying this symptom, even if they don’t know what to call the behavior.

What Causes Lethargy in Dogs?

Dog lethargy can be caused by lots of different health conditions. Pet owners need to be aware of the various things that can cause this behavior so that they know when to be concerned about their dog’s lack of energy or interest in being active.


Dogs who are in severe pain are often lethargic. This is partially because movement is painful for them, but it can also be related to nausea and worry that they could also be experiencing. Pain can be easy to recognize because your dog might not want you to touch them, or they might growl when you get close to them. Pain could be caused by internal injuries, broken bones, or systemic conditions.


Dogs who have ingested something poisonous or who have been bitten or stung by an insect or something like a snake can also be lethargic. This is usually a medical emergency since toxicity can move very fast and can kill a pet in a matter of hours. Toxicity might also be accompanied by vomiting and diarrhea, or seizures.

Digestive Issues

Digestive upset can lead to lethargy if your dog feels very sick or if they are dehydrated because of their digestive issue. Some pets will also stop eating for a prolonged period when they are dealing with a GI problem, which can lead to weakness. If your dog is not eating or drinking due to a digestive upset or they are vomiting and have diarrhea, they need to see the vet right away.

Neurological Disease

Dogs with neurological issues will often be lethargic because of the effort that it takes to organize their limbs to be active and sometimes as a result of the damage to their body’s overall well-being caused by these problems. Neurological diseases are usually quite recognizable since your pet will display odd, uncoordinated movements, they might drool or pant excessively, and they could struggle to even get up and down.


Dogs who have become dehydrated can be at risk for heatstroke, which is life-threatening. Pets who are dehydrated might act listless, be unwilling to get up or down, and might collapse. If your pet is not getting access to enough water or they have been exercising outside in the heat, dehydration could be the reason for their lethargy. This is always a medical emergency, and you should get your dog in to see the emergency vet right away.


Dogs can get diabetes just like people, and this condition can impact their ability to regulate blood sugar. This means that they might have suffered from a wide array of symptoms, from weight gain to weight loss, excessive water intake, and weakness and coordination issues. Some dogs will also become quite lethargic and quit eating or drinking.

This condition requires treatment, and your pet will need to visit the veterinarian to be examined. Your vet can give your dog the right medications to help them maintain healthy levels of blood sugar, and you might need to make changes to their diet as well.


Dogs that are quite old can sometimes become very lethargic as they near the end of their lives. This is one of the signs that your elderly pet might be nearing the end of their lifespan. You should reach out to your vet and ask them if you can bring your pet in to be examined. Sometimes there will be health concerns that you can address related to your dog’s aging process, but sometimes there is not much that can be done for a very old dog. Lethargy in older dogs is often related to the aging process and can be quite natural.

Dog Lethargy Can be Related to Many Things

Dog lethargy is often related to a health issue that needs to be addressed. The difference between lethargy and your dog being a little tired is usually obvious to pet owners, and you should trust your instincts if you think your dog is lethargic. Many of the health issues that your pet might have related to lethargy will necessitate a visit to the vet.

Systemic health issues like diabetes will require lifelong management. Emergency conditions like poisoning will often require that your pet remains at the clinic for a few days as they are being treated, but your pet might not need any further long-term care related to this kind of lethargy. You should never ignore lethargic behavior, even in very old pets, as this can be a sign that something is very wrong with your pet’s health. Your vet will be able to check on your pet and figure out the reason for their lethargy and create a treatment plan to help them to feel better.

If your dog is showing signs of being lethargic it is important to book an appointment at any of our Heart + Paw locations so you can talk with a veterinarian about your pet’s behavior. 

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Heart + Paw was founded in 2018 by Chief Veterinary Officer Dr. George Melillo, who currently serves the Mid-Atlantic area. Heart + Paw offers a combination of veterinary care, pet grooming, and dog daycare to help be a resource in your pet parenthood journey.

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