It appears his disability was not service connected if I read his Certificate of Discharge correctly. It is difficult to read on-line.

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Charles Henry Herzog, Private, Company D, Stewart's Missouri Cavalry

On his certificate of discharge the Surgeons state:

I certify, that we have carefully examined the said Charles Henry Herzog of Lieut. Darr's Company, and find him incapable of performing the duties of a soldier because of the loss of index finger on right hand before enlistment
/s/ George Reeder, Chas L. Henderson, J. Andrews
Surgeons