Dogs and cats are renowned for their ability to bond with humans–and with each other. Clearly Oliver and Pepper were very close. It is not surprising that Pepper’s behavior has changed since Oliver passed away.
Although pets may experience periods in which they exhibit behavior similar to humans in mourning, these periods generally do not last for very long. Dogs and cats are quite good at living in the moment.
Therefore, if Pepper’s depression has lasted longer than a week or two, you should investigate to make sure that nothing else could be causing the abnormal behavior. Two major possibilities come to mind.
First, there is the chance that the stress of losing a friend has uncovered a pre-existing medical condition in Pepper. I recommend that you have a veterinarian assess him to rule this out.
Second, Pepper may be responding to your grief over the loss of Oliver. It is natural for people to be depressed after the loss of a pet, and that depression can last a very long time. Dogs are phenomenally good at reading our emotions. And they often reflect those emotions back to us.
Your grief over Oliver’s passing is natural. If a veterinarian gives Pepper a clean bill of health, then I recommend that you continue to work on developing new routines with him. Over time, the situation should improve for both of you.