Just like people can get depressed I think animals can get depressed when they suffer a great loss of relationship from another family member, buddy or a human.
Select National Geographic Do Animals Get Depressed to read more.
Select Animals can help us humans with depression to see the benefits of having animals. If you can not afford the cost of a pet consider volunteering your time at an animal rescue organization close to your home. You will not only be helping the animals and the humans who created this wonderful place you will be helping yourself.
The bible is clear we must help another in order to help ourselves – remember volunteering to help another human or animal may be the best medicine the doctor could order
GOD bless you and your family two and four-legged!