Although no differences were observed in uterine SOD expression, Nascimento et al. [14] reported reduced endometrial CAT immunostaining in cats with pyometra, while Abdelbaset et al. [45] demonstrated serum CAT values twice lower in cats with pyometra compared to healthy cats, confirming the reduction of this enzyme in pyometra [13,45]. This evidence concerns the gene SOD1 and pyometritis.