Okla. Stat. tit. 12, § 12-1459: No further pleading allowed - Similarity to civil action

No other pleading or written allegation is allowed than the writ

and answer; these are the pleadings in the case, and have the same

effect, and are to be construed and may be amended in the same

manner, as pleadings in a civil action; and the issues thereby

joined must be tried, and the further proceedings thereon had, in

the same manner as in a civil action.