Similar to humans, dogs can experience periods of sadness and depression. However, unlike humans, dogs are unable to express or communicate their feelings of depression or sadness.
Changes in your dog's disposition could be caused by a number of factors, including the loss of another pet or loved one, illness or injury, or simply being bored out of their minds.
Possibly, your dog is no longer interested in food. Or, your dog may begin to eat significantly more than usual, as food can sometimes provide comfort. Both of these behaviours may indicate that your dog is unhappy. Changes in a dog's eating habits can also affect his or her weight. Changes in your dog's eating habits or weight may indicate that he or she is feeling depressed.
Sad or depressed dogs are more likely to lie around and refuse to interact with anyone in the home. This could be due to old age, but if it occurs suddenly and you observe your dog moping or sleeping excessively, it could be a sign of depression.
When your dog is happy or optimistic, its tail will be wagging vigorously. The dog's tail will likely be lowered or tucked between its legs when it is sad. Slow tail wagging and a low tail position indicate fear and also sadness.
If your dog, who is typically calm and placid, has suddenly begun to growl and display aggressive behaviour, it may be a sign of depression. If you notice that your dog is becoming much more rough with its toys and more aggressive towards the people in the house, it is likely that they are feeling depressed. Aggression can also be a sign of physical discomfort in your dog.
Sad and depressed dogs may no longer want to go for walks or play. If your dog suddenly stops jumping for joy whenever you grab its leash to take it for a walk, this is an indication of depression. They may no longer respond the same way to their favourite toys and treats.