Hence, we decided to methodologically characterize the occurrence of dystocia in the following genotypes: WT, Mmp2+/−, Mmp2−/−, Mmp9+/−, Mmp9−/−, Mmp2+/−Mmp9+/−, Mmp2−/−Mmp9+/−, Mmp2+/−Mmp9−/− and Mmp2−/−Mmp9−/− (dKO). This evidence concerns the gene MMP9 and dystocia.