ELYRIA, April 8 (AP) An anesthesiologist testified on Monday that Ohios lethal injection procedure is not appropriate for dogs or cats, let alone humans. Dr Mark Heaths testimony on behalf of two murder defendants came in a Lorain County hearing on the constitutionality of states method for putting prisoners to death.

Dr Heath, an assistant professor of anesthesiology at Columbia University in New York City, says its possible to perform lethal injection of prisoners in a humane manner, but that Ohios method falls below the standard for euthanizing household pets. Under cross-examination, Dr Heath testified that he is personally opposed to the death penalty in whatever form its carried out. He also said he has not found an acceptable method for lethal injection of humans in any state.

The two men facing murder charges say the states lethal injection procedure does not give the quick and painless deaths required by state law. Lethal injections are on hold nationally while the US Supreme Court considers a challenge in a case from Kentucky, which is among the roughly three dozen states that administer three drugs in succession to sedate, paralyze and kill prisoners.

The major criticism of the three-drug execution procedure is that if the executioner administers too little anesthetic or makes mistakes in injecting it, the inmate could suffer excruciating pain from the other two drugs.

Dr Heath testified that the design of Ohios death house was problematic because it separates the inmate from the person administering the drugs in two separate rooms. The rooms are separated by a one-way mirror. He said potassium chloride, the third drug administered, which stops the heart, is sometimes used for euthanizing animals. He added that in veterinary procedures the person administering the drug has to be trained in assessing the depth in which the animal is sedated and would have to be present at the bedside.

Other problems that could occur come during the mixing of the anesthetic - sodium thiopental, which is sold in powder form - and the insertion of the catheters in the veins and kinks in the IV tubing, he said.

Difficulties with two executions in recent years, in which the execution team struggled to find suitable veins in inmates arms, brought complaints that the method is unconstitutionally cruel and unusual. Ohio officials stand by the procedure.

Heath testified on behalf of defendants Ronald McCloud and Ruben Rivera, who are accused of separate murders and could receive death sentences if convicted.

The state was expected to counter with expert witness Dr. Mark Dershwitz, an anesthesiologist from Massachusetts who will testify via video conference Tuesday.

Ohio has executed 26 inmates since it resumed putting prisoners to death in 1999.