There is no single right interpretation to this behaviour. It is commonly believed that cats purr when they are in the mood to make social contacts. They signal satisfaction and well-being both to other cats and people. All cats, regardless of age, sex or race, purr at the same frequency of 25 cycles per second.
Purring does not always mean that the cat accepts the whole world around it and that it feels good. Cats purr even when feeling unwell and/or to avoid discomfort or indicate helplessness. They also purr as in the following situations:
• When they are scared, to relieve stress and to calm down,
• To reassure other cats that are in pain or suffered an injury,
• When they are experiencing labour pains.