Causes of Lethargy in Dogs

Written and verified by the biologist Paloma de los Milagros

Last update: 21 December, 2022

Lethargy in dogs is a common symptom that can be caused by a wide array of different factors. Paying attention to how often it occurs, if there are any additional symptoms, or whether there has been a drastic change in your pet’s environment may help you to understand what has caused the issue.

Lethargy is a state of drowsiness or extreme sleepiness. It may be caused by an underlying illness, seasonal changes, or other changes in the animal’s environment. This apathetic behavior may also be the result of laziness, but shouldn’t last more than a few days.

However, if this lethargy starts to affect your pet’s daily routine, appetite, or mood, it’s best to seek help from a professional.

Main causes of lethargy in dogs

The most common pathological causes of lethargy in dogs include:

• Infections, including parvovirus, distemper, kennel cough and leptospirosis
• Metabolic disorders, heart or liver problems, diabetes or hypoglycemia
  
• Canine anemia
• The presence of intestinal parasites
• Poisoning as a result of ingesting toxic substances or spoiled food products
• Pain caused by an injury or illness

To determine whether the lethargy is caused by an underlying illness, you’ll need to keep an eye out for any other symptoms, such as vomiting, diarrhea or growling. Informing your vet of anything out of the ordinary will help them make a proper assessment of your dog’s health.

Other possible causes of lethargy in dogs include traumatic experiences, such as a sick owner, or moving house. Stress, fear and anxiety can all lead to apathy in dogs, to the extent that they may stop doing things they usually enjoy, such as going out for walks, or eating their favorite food.

This state of drowsiness can also be caused by an adverse reaction to medication or antiparasitic treatment. Antiparasitic treatments (especially topical remedies) often contain chemicals with rather aggressive smells, which can lead to feelings of lethargy. As such, it’s important to consider the size of your pet, and administer the proper dose as explained in the instructions.

How to combat lethargy

Once the vet has diagnosed the cause of the lethargy, they will prescribe the appropriate medication or treatment plan. In the case of stress, if the animal is unable to adapt to the new situation, it may be necessary to hire a trainer or ethologist who may be able to improve the situation.

Until your pet regains its normal mood and starts exercising properly again, you’ll need to keep a close eye on their diet to make sure they don’t gain weight. However, bouts of lethargy in dogs are often accompanied by loss of appetite, so weight-gain shouldn’t be your main concern.

To determine whether or not your dog is lethargic, you first need to be aware of how long a healthy dog should sleep for. An average of 10 hours of sleep a day is perfectly normal, which means that the chances of you finding your dog asleep are around 50%. With this in mind, it’s important to check whether your dog is getting enough sleep at night.

Your dog’s age

It’s also important to think about how old your pet is. As well as spending more time eating, puppies also need to sleep more than adult dogs. So, if your puppy sleeps 15 – 20 hours a day for the first few months, there’s no need to worry. Similarly, as adult dogs get older, they start experiencing more aches and pains. As such, it’s normal for them to sleep for longer.

As with people, lethargy in dogs is the body’s natural response to situations of great stress or change. However, if this lasts longer than usual, you must book a check-up with your vet, who can help your pet get back to leading a happy and active life.