Decreasing pH of mammary gland secretions is associated with parturition and is correlated with electrolyte concentrations in prefoaling mares.
Authors: Canisso I F, Ball B A, Troedsson M H, Silva E S M, Davolli G M
Journal: The Veterinary record
Summary
# Editorial Summary: Mammary pH as a Foaling Indicator Monitoring mammary gland secretions offers a practical, non-invasive method for predicting parturition in mares, as researchers tracked pH changes and electrolyte shifts in 14 pregnant mares (seven first-time and seven experienced mothers) from late gestation through foaling. Daily secretion samples collected from day 310–320 of gestation onwards revealed a sharp drop in pH immediately before delivery, with 79% of mares (11 of 14) exhibiting pH ≤7.0 foaling within 24 hours—a highly significant finding (P<0.0001) that correlates strongly with the physiological changes occurring before parturition. The pH decline mirrors substantial electrolyte remodelling in mammary secretions: calcium and potassium concentrations increased significantly whilst sodium and chloride decreased markedly in the final 24 hours before foaling, with pH showing particularly strong inverse correlations with calcium (r=−0.88) and sodium (r=0.87) levels. For practitioners, this means evening measurement of mammary pH using either a pH meter or strip test provides a reliable, affordable screening tool to predict imminent foaling in most mares, offering a practical addition to pre-foaling management protocols and reducing the need for more intensive monitoring in the final days of gestation.
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Practical Takeaways
- •Daily evening pH testing of mammary secretions using a simple pH meter or strip can reliably predict foaling within 24 hours in most mares—a practical, non-invasive tool for monitoring pregnant mares
- •A pH of ≤7 is a strong indicator that foaling will occur within 24 hours, allowing better timing of supervision and attendance at parturition
- •This method works equally well in primiparous and multiparous mares, making it applicable across different mare populations
Key Findings
- •pH of mammary gland secretions significantly decreased on the day of foaling (P<0.0001), with 11/14 mares having pH ≤7 foaling within 24 hours
- •Electrolyte concentrations changed significantly from day -1 to foaling: Ca²⁺ and K⁺ increased while Na⁺ and Cl⁻ decreased
- •pH was highly correlated with Na⁺ (r=0.87), Cl⁻ (r=0.85), Ca²⁺ (r=-0.88), and K⁺ (r=-0.80) concentrations
- •Two pH measurement methods showed high agreement (r=0.93), validating the use of portable pH strips for practical application