(a) The commission may require urine samples to be frozen for a period necessary to allow any follow-up testing to detect and identify a prohibited substance. Any other specimen shall be maintained for testing purposes in a manner required by commission rule.
(b) If a test sample or specimen shows the presence of a prohibited substance, the entire sample, including any split portion remaining in the custody of the commission, shall be maintained until final disposition of the matter.
(c) A license holder whose animal test shows the presence of a prohibited substance is entitled to have a split portion of the test sample or specimen tested at a testing facility authorized to perform drug testing under this subtitle and selected by the license holder. The commission shall adopt rules relating to split testing procedures.