Lack of energy can also be referred to as low energy, lethargy, or listlessness. An owner who is aware of their dog’s normal behavior and energy level will notice it when their dog has less energy than usual. A dog lacking energy will seem to be weak and inactive, with less interest than normal in everyday activities. While any pain or medical disorder can be a reason for a dog’s lack of energy, there are several conditions that are more predictably linked.

A lack of energy is not always serious, and does not always indicate illness. It is normal for a dog to lack energy after strenuous exercise, a walk in hot weather, or at its normal bedtime. Everyone gets tired from time to time. It is when a phase of lowered energy is more pronounced or lasts longer than usual that one should check for other symptoms that could indicate a more serious condition.

Your dog can exhibit a lack of energy for three basic reasons: normal tiredness, a deficit in basic nutritional needs, or a more serious illness. When a dog is tired, it needs to rest. An anorexic dog is not getting adequate nutrition, and a dehydrated dog is lacking adequate fluids; both conditions are likely signs of a deeper disorder. If your dog is suffering from an illness, it’s energy is depleted from fighting the illness.

Partial anorexia, or hyporexia, is a condition in which the dog does not eat enough to maintain its weight, while a dog experiencing complete anorexia has not eaten in three or more days.  Anorexia is not a disease in itself, but is a sign of a deeper emotional or physical disorder, such as a digestive disorder, dental problems, or kidney failure. A dog who is panting or drooling excessively, has dry and sticky gums, does not have normal physical coordination, and whose skin does not spring back into shape when pulled, may be dehydrated. A dehydrated dog may be less interested in water than a normal dog. Lack of food or water will fatigue your dog. 

Anemia happens when the protein hemoglobin can not release oxygen to bodily tissues. Besides lack of energy, a dog suffering from anemia can exhibit seizures, vomiting, excessive panting, and abdominal pain. Anemia results from either a genetic disorder or eating an analgesic, such as aspirin or ibuprofen. 

Cancer is an uncontrolled growth of abnormal cells. It can happen in many different parts of a dog’s body. While it is more likely to occur in older dogs, it can happen to dogs of any age. Besides lethargy, cancer symptoms are multifarious, and can include decreased appetite, weight loss, vomiting, great thirst, and frequent urination, among many other possible symptoms. 

Rocky Mountain Spotted Fever is usually spread by the bite of an infected tick. It occurs all over the United States. Besides a lack of energy, typical symptoms include high fever, coughing, vomiting, and diarrhea.

A tired dog simply needs to recoup its energy. If your dog has engaged in strenuous physical activity very recently, give it a chance to rest. However, if your dog is still listless at the end of one full day, you should seek the advice of your veterinarian. Dogs suffering from anorexia, dehydration, anemia, cancer, and Rocky Mountain Spotted Fever all require immediate veterinary evaluation, and should have advanced blood work to determine any underlying causes.

Your first concern should be to make sure your dog is eating and drinking normally. A dehydrated dog may be less interested than normal in drinking. If your dog has not eaten in a day, try feeding the dog small pieces of a strong-smelling food, putting the food in its mouth and holding its mouth shut until it swallows if necessary. A dehydrated dog can be treated by dousing it in cool (not cold) water. If your dog continues to refuse food and water, your vet may try fluid therapy through subcutaneous administration of lactated Ringer’s solution, or feeding the dog via a feeding tube. 

The initial goal of anemia treatment is to stop the dog’s system from being further damaged. In the case of ingestion of aspirin or ibuprofen, vomiting may be induced to keep the analgesic from spreading. Dogs with more severe symptoms may need oxygen therapy, intravenous fluids, or blood transfusions. 

Cancer must be immediately and aggressively treated. Depending on the type of cancer, surgery is usually the first course of treatment. If surgery is not possible or the tumor cannot be fully excised, the dog may need radiation or chemotherapy. A dog with Rocky Mountain Spotted Fever is typically treated with a full course of antibiotics, and may need intravenous administration of fluids, iron supplements, and blankets to keep warm.

To help keep your dog’s eating and drinking habits regular and consistent, always make sure that fresh, clean water is easily accessible, and feed a healthy and appealing diet on a regular schedule. Though genetically-based anemia can not be prevented, you can keep such analgesics as aspirin and ibuprofen properly stored and out of your dog’s reach. 

To avoid Rocky Mountain Spotted Fever, if there are ticks where you live, keep your dog away from tall grass and groom frequently to remove ticks before they bite and attach to the dog. Rocky Mountain Spotted Fever can be deadly, and prevention is much easier than treatment. 

A healthy diet, regular exercise, veterinary supervision will help keep your dog healthy overall, which is the best preventive for cancer. However, many cancers can not be prevented, so always stay aware of your dog’s normal behaviors, routines, and overall condition. Careful monitoring of your dog can help you detect any irregularities and discover cancers early. 

Dehydration treatment averages $400, while the average cost of treating anemia is $1400. It costs an average of $3500 to treat Rocky Mountain Spotted Fever. Treating kidney failure, a common cause of anorexia, averages $4000. Different cancers have different treatment costs; the average cost of treating liver cancer is $8500.