I have found that my cat also purrs when he is happy sad or hurt. Now this intruged me so I did some research and found the purring has nothing to do with being happy or as a way of telling your cat loves you. Purring actully takes place deep in the cats cheast tho it may fell like its comeing from its throat. Purring is a cats way of calming its self down. Many cats purr when giving birth when hurt and even when going to the vet