The barcode scanning apps work because barcodes have a very specific pattern that can be used to identify the product, and are designed with this sort of identification in mind. Building something to identify something like a species would be significantly more difficult due to variation. That's not to say you couldn't come up with a creative way to accomplish what you want (i.e. write a program where you take a photograph of the horse and it gets uploaded to a service where a human being classifies it, or an app where you identify some of the key features (size, color, etc) and the app gives back some the best matches in it's database of known species and a confidence score of how likely each one is. Good luck!