i did find this, the obstruction was gravel, my guess would be the example you found would also be gravel..... in this case it is a pound of gravel and a 200lb tortoise, which would have me think the gravel was ingested all at once and purposefully......also i'm guessing the pound of gravel was not the primary cause..... i had 130-140lb dog eat at least a pound of dirt..... you know how gas grills have that pan for catching grease? if its not in the grease drips on the ground, i caught my dog eating the dirt under the grill the next day, a pound of dirt is on the conservative side.......Surgery of sand-impacted Aldabra, hopefully with X-rays).
SURGICAL AND MEDICAL MANAGEMENT OF A GASTROINTESTINAL OBSTRUCTION IN AN ALDABRA TORTOISE, Geochel ne gigantea Mark Kombert, V '* Randall .. Junge, S, DACZM cause.
i don't think you could find one, possibly one of your veterinarian friends could get you one? i 'd say don't feed your tortoises off the ground, feed them off some sort of hard surface..... they do eat substrate, gravel appears to be a riskier culprit, i do believe there is more to it than the amount of substrate eaten stuck to food....What verifiable proof is there? You want me to go find an X-ray of a sand impacted tortoise?