Decreasing pH of mammary gland secretions is associated with parturition and is correlated with electrolyte concentrations in prefoaling mares

Abstract

The objectives of this study were to determine pH of the mammary gland secretions and the corresponding electrolyte concentrations in prefoaling mares. Pregnant mares (seven primiparous and seven multiparous) were monitored daily from 310-320 days of gestation until parturition. Prefoaling mammary gland secretions were collected, and pH was immediately determined with a pH meter and pH strip test. An aliquot of prefoaling mammary secretions was frozen and stored until further analyses. After parturition, samples from day -4 to 0 (day of foaling) were thawed and electrolyte concentrations (ie, Ca(2)(+), Mg(2)(+), Na(+), K(+) and Cl(-)) were determined with an automated analyser. Data were analysed via a mixed model with the mare as a random effect. Correlations were determined between pH and electrolyte concentrations by the Pearson product-moment for each pair. There was significant reduction in pH of mammary secretions on the day of foaling (P<0.0001), and most mares (11/14) with a pH ≤7 foaled within 24 hours. There was high correlation between the two pH methods (r=0.93). Additionally, there were significant (P<0.05) increases in Ca(2+) and K(+) concentrations, and significant decreases in Na(+) and Cl(-) concentrations from one day before to the day of foaling. The pH of mammary secretions was highly and significantly (P<0.001) correlated with Na(+) (r=0.87), Cl(-) (r=0.85), Ca(2+) (r=-0.88); and K(+)(r=-0.80) concentrations, and moderately correlated with Mg(2+) (r=-0.58). Daily evening pH measure of the mammary gland secretions can predict foaling in most mares.

Prepubic tendon rupture in the mare

“…The majority of mares with a pH <7 have been shown to foal within 24 h (Canisso et al . ). Other clinicians have confirmed this; in addition it is possible that the pattern of pH change may reflect fetal maturation (Ellerbrock and Canisso ), which is an exciting prospect for the future.…”

Monitoring of the mare during the perinatal period at the clinic and in the stable

“…1984) and pH mammary gland secretions (Canisso et al . 2013) are more precise. The most precise test allows one to estimate approaching labour with accuracy of up to 12 h. Major changes were also documented for sodium concentration, which starts decreasing a few days before parturition, while potassium increases slightly.…”

A regression model including fetal orbit measurements to predict parturition in Standardbred mares with normal pregnancy

“…The only method to predict the day of foaling is to identify the increase of calcium concentration in mammary secretions, which occurs 24-12 hours before foaling [4][5][6][7]. More recently, some studies showed a decline of pH in mammary secretion of normal pregnant mares [8][9][10].…”