Sorry OM post legs/straight from the hocks down have absolutely nothing to do with the genetic condition HyPP. HyPP produces excessive muscling via mutated genes. It does not produce what was shown by the pic posted by the OP. If you would like to discuss the effects of HyPP I suggest some simple google searches and then follow through with the stated rules from AQHA here and in the USA. I get you don't like QH because I and a few others own them, but please can we read some sensible and half relevent replies?