The term "short-legged" is a euphemism for a dwarf Dexter, or one that carries the dwarfing gene. The dwarf condition in Dexters is labeled chondrodysplasia. It is a condition most evidenced by short legs, wide heads and bodies, and deep chests.
It is possible to have a Dexter that is not a dwarf have short legs, too. There is a range for both types and the ranges may overlap.
Lots of breeders claim that they have solved the problem of selectively breeding to produce Dexters that are as short as the chondro carriers without actually having the gene for dwarfism. They've coined terms for their creations. They call them "Proportional", or "medium legged". Often it's no more than the difference that may exist between siblings.
I've actually bought heifers that appeared to be "proportional", but once I got them home and had them DNA tested, they proved to have gotten their small size the old fashioned way, through chondrodysplasia.
For all practical purposes, and by common usage, a short legged Dexter is a carrier of the chondro gene, a dwarf Dexter.
The horns on the Dexters pictured here are beautiful and distinctive. I doubt you'd make them better looking by taking their horns off.
Genebo
Paradise Farm
http://paradisedexters.com