Animals are intelligent and when their buddy has suddenly gone, it is common for them to pine for them. This may display itself as visual sadness, they may not have their usual appetite or may be showing other behavioural signs that something isn’t right.
If you had your pet put to sleep at home, it can help for their buddy to come and look at their body after they’ve gone. In the animal world, this can help them to understand.
If your pet is grieving too, it’s important to carry on their daily routines as normal, spend more time with them if you can, playing and exercising. As well as helping them, this can also help your own grief. Watch their appetite to see if it’s going back to normal. If the behaviour lasts more than a couple of weeks, it may be time to get the vet to check your pet over to make sure nothing else is going on.