Sentence:  In criticism of the latter 's views , his conclusions were based upon <WSD>dog</WSD> lung injection studies in which all of the vascular channels were first filled with a solution under pressure and then were injected with various sized colored particles designed to stop at the arteriolar level . 
Meaning of the word marked with <WSD> tags:  a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds