dog lethargy in boston, ma

Why is My Dog Acting Lethargic?

Do you have a dog? Have they been acting lethargic lately? Are you concerned about what this lack of energy could mean for your pet? Should you take your dog to the vet every time they seem to be lethargic about something?

If you’re asking yourself any of these questions, you’re not alone. Many pet parents worry about lethargy in their dog, and in some cases, lethargy can certainly signify a serious underlying health problem. In the article below, we’ll help you understand more about what lethargy could mean for your dog and when it may require a trip to the vet. Read on to find out more.

Mild Causes of Dog Lethargy

Mild causes for a dog’s lethargy could include kennel cough, stress, or anxiety.

Kennel Cough

Kennel cough may cause dogs to seem lethargic for a short time as their bodies recover from this infection. Kennel cough, which is typically caused by a type of bacteria called Bordetella, is a common illness that is very similar to a cold. In healthy, adult dogs, it is not life-threatening and can run its course without vet care in most instances.

If your dog has recently stayed at a kennel or dog daycare and seems to be lethargic, they could be coming down with kennel cough.

Stress or Anxiety

Stress and anxiety are also factors that may contribute to lethargy in a dog. If your dog seems to be anxious a lot of the time, or if recent changes in your household have led to them feeling stressed, this could be the underlying cause of the lethargy.

Dogs who do not seem to have any physical symptoms outside of lethargy may be dealing with a mental or emotional health problem instead.

Moderate Causes of Dog Lethargy

Moderate causes for a dog’s lethargy could include an infection, arthritis.

Bacterial or Viral Infection

Any type of bacterial or viral infection, or any type of illness at all, can contribute to lethargic feelings in dogs, too. If your dog is lethargic and shows symptoms of an infection or illness of some type, it is important to take them to the veterinarian to figure out what’s going on.

If the infection is bacterial or fungal, your vet can prescribe medication to help your dog recover quickly. If it is virus, medication won’t help, but your vet may still give your dog a round of steroids to help their body fight off the virus effectively.


If your dog is older and has some mobility issues, arthritis could be the cause of the lethargy instead. Arthritis is very common in dogs as they get older, and any dog of any breed can potentially be affected by this condition. If you know or suspect your dog has arthritis, talk to your vet for a diagnosis and for management options.

While there is no treatment for arthritis, you can help your dog manage the condition by taking care of the pain. Laser therapy and Pain medication, which may need to be given daily, may help your dog feel better and cut down on the lethargy as well as other symptoms.

Severe Causes of Dog Lethargy

Severe causes of a dog’s lethargy could include Heartworm disease, cancer and it is important to talk with your vet about how your pet is feeling.

Heartworm Disease

Heartworm disease can cause lethargy, weakness, and an unwillingness to be very active. If your dog has trouble getting up and playing without needing to catch their breath, or if they cough frequently when playing or eating, then there is a chance they could have heartworm disease.

Many symptoms of heartworm disease mimic those of congestive heart failure. In both instances, you will need a vet’s diagnosis to determine what’s wrong with your dog. Your vet can also help you choose the right management options for these conditions moving forward.


Most types of cancer can cause a dog to feel excessively tired almost all the time. If your dog’s energy levels have suddenly dropped and you can’t figure out why, there is a chance it could be cancer. However, there are many other, more common conditions that are more likely, so it is important not to jump to conclusions.

Take your dog to the vet to have them fully examined and checked out by a professional. This way, you’ll be able to find out for sure whether they are dealing with cancer or some other, more manageable problem instead.

Talk with Your Vet to Figure out Why Your Dog is Lethargic

With so many potential underlying causes of lethargy in dogs, it is easy to see why this symptom is concerning to pet parents. A dog who is lethargic could have something as serious as cancer, but they could also just be sleepy, and it may be difficult to tell in some instances.

If you have any questions or concerns about your dog’s health and wellness, talk to your Boston Veterinary Clinic vet by booking an appointment online for more information. And if your dog’s lethargy is accompanied by any other concerning symptoms, it is a good idea to take them to the vet to be checked out thoroughly and to be diagnosed.