Maybe a cross-species IQ score would be interesting. Chimpanzees and corvids both can solve many IQ-test problems, but also are not experiencing the Flynn effect as far as we know. So we could measure IQ in multiples of a chimp's IQ, just like we measure cars in multiple's of a workhorse's sustainable pulling output. (Which is actually a less objective measure, when you think about it; we were breeding workhorses to increase that very target at the time the concept of "horsepower" was invented!)
That would be a great start. And it would also force us to acknowledge that a lot of the things that we are doing with these animals are utterly un-ethical.