IgG and lysozyme concentrations in fetal fluids of term pregnancy dogs

In the dog, the endotheliochorial placenta allows only the 5-10% transfer of maternal antibodies to the fetus, but the timing as well as the factors influencing the IgG trans-placental transport were not fully investigated. The aims of the present study were the following: 1) to assess the presence of both IgG and lysozyme in amniotic and allantoic fluids collected from full-developed and viable newborn puppies born by elective Caesarean section at term, and possible correlations between amniotic and allantoic IgG and lysozyme levels; 2) to verify possible differences in IgG and lysozyme concentrations between the two fluids; 3) to detect possible differences in IgG and lysozyme fetal fluids levels in relation to the maternal breed body size and parity, as well as to the neonatal gender. The study, performed on 41 purebred bitches submitted to elective Caesarean section at term, enrolled 142 puppies, 74 males and 68 females, born mature, viable, without gross malformations, and with a normal weight. At surgery, a total of 129 amniotic and 84 allantoic samples were collected for IgG and lysozyme analysis. Class G immunoglobulins and lysozyme were detected in both fluids, but IgG concentrations were higher (p<0.01) in amniotic fluid. Moreover, a significant positive correlation (p<0.01) between IgG amniotic and allantoic levels, but not for lysozyme, was observed. A significant effect of the maternal parity (p<0.05), but not of the breed body size, on the amniotic IgG concentrations was found, whereas the newborn gender was not associated to different IgG or lysozyme amniotic or allantoic levels. Given the significant contributions of fetal fluids to fetal and neonatal health, the results demonstrated that the amniotic and allantoic fluids play a role in the immune protection of the fetus/newborn also in canine species, although additional researches are needed to better elucidate both the origin of IgG and lysozyme, and the factors influencing the wide inter-individual variations.