Enables L-threonine 3-dehydrogenase activity and identical protein binding activity. Acts upstream of or within threonine catabolic process. Located in mitochondrion. Is expressed in several structures, including alimentary system; nervous system; nose; tail mesenchyme; and yolk sac endoderm. Orthologous to human TDH (L-threonine dehydrogenase (pseudogene)). [provided by Alliance of Genome Resources, Apr 2022]