Okla. Admin. Code § 325:40-1-7
No person shall bring onto the enclosure of a racing organization, or enter or cause to be entered in any race, any horse which has been "nerved" or has had any nerve removed from the leg of such horse, except as provided by this Section. Notwithstanding the prohibition against "nerving," a horse upon which a posterior digital neurectomy has been performed, commonly known as "heel nerving," is not ineligible to race, provided that the official veterinarian is satisfied that the loss of sensation to such horse due to the posterior digital neurectomy will not endanger the safety of any horse or rider, that the prior approval of the official veterinarian has been obtained, that the racing secretary is notified of such "nerving" at the time such horse is entered in a race and its registration certificate marked to indicate such "nerving." The racing secretary shall maintain a list of "nerved" horses which are on the grounds, and shall make such list available for inspection by other licensees participating in the meeting.
Okla. Admin. Code § 325:40-1-7