What Causes Lethargy and Loss of Appetite in Dogs?

By Staff WriterLast Updated December 09, 2023

The most common cause of lethargy and loss of appetite in dogs is an infection in the body. Other reasons a dog would be lethargic and uninterested in eating are pain, medications, liver disease, heart disease and diabetes mellitus, according to WebMD. There are many conditions that would cause a dog to become weak, lethargic and have a loss of appetite, so it is important to bring a dog to see a veterinarian for a proper diagnosis.

Certain medications for humans, including ibuprofen, are toxic to dogs, which could cause lethargy, loss of appetite and other symptoms. Any time a dog has accidentally consumed human medication, it is important to contact animal poison control or a veterinarian immediately for proper treatment.