You can't tell a lot about what is happening in a cat's colon with an x-ray. You should at least get an ultrasound; it will show any gallstones, inflammation in the colon, etc. Expensive, but really necessary.
EXCELLENT! No animal should be fed kibble - if people knew what is in it, no one would buy it. Commercial meat packing businesses throw bones, hooves, and offal in a pile outdoors and after a time of rotting out there they sell it to a pet food distributor who puts it, decomposing bacteria and...
