I have done two readings for pets, one was to know the final destiny of a cat my family lost many years ago, the result was very healing and made me feel happy: our little cat got lost but another family adopted him and care very much for him, for that reading I used the RWS.
The second reading was this weekend regarding a sick catfish, I used the spread posted in this thread and the World Spirit deck, the reading talked to me about the rest he needs and his force to live or endure the sickness, I hope he gets well soon.