Lethargy is another word for lack of energy and weakness. Much like humans, dogs also go through periods of lethargy, which itself is a symptom that gives an indication of many illnesses in dogs.
Lethargy can range from:
- Mild: You would find your dog is not as playful as usual but continues the daily routine.
- Moderate: You notice that your dog is not interested in playing and is sleeping more than usual.
- Extreme: Your dog barely moves or finds it difficult to even hold his head up.