Prevalence and prognostic importance of hypomagnesemia and hypocalcemia in horses that have colic surgery.

This study analyzes the occurrence and implications of low magnesium (hypomagnesemia) and low calcium (hypocalcemia) levels in horses that have undergone colic surgery.

Objective and Methodology

• The research focused on determining the prevalence of hypomagnesemia and hypocalcemia in horses which required surgical intervention due to colic. A total of 35 horses with surgically managed colic were included in the study.
• As part of the methodology, the researchers measured the horses’ serum concentrations of total magnesium (tMg2+) and calcium (tCa2+), as well as ionized magnesium (iMg2+) and calcium (iCa2+) both before surgery and at 1, 3, 5, and 7 days postoperatively.
• In addition to this, a lead-II ECG was performed and pertinent clinical data were collected at each time point.

Findings

• Before surgery, tMg2+ and iMg2+ concentrations were below the reference range in 17% and 54% of the horses respectively while 57% and 86% of the horses had serum concentrations of tCa2+ and iCa2+ lower than the reference range.
• The horses with strangulating lesions on their gastrointestinal tracts had noticeably lower pre-surgery concentrations of iMg2+ and iCa2+, in addition to an elevated heart rate when compared with horses with nonstrangulating lesions.
• It was observed that the horses that developed postoperative ileus (a disruption of the normal propulsive ability of the gastrointestinal tract) typically had significantly lower iMg2+ levels after surgery.
• It was found that serum concentrations of magnesium and calcium, both total and ionized, were significantly correlated with the PR, QRS, QT, and corrected QT (QTc) intervals on ECG recordings.
• The Researchers also found that horses that were euthanized at the time of surgery had significantly lower pre-surgery iMg2+ levels compared to horses that survived.
• However, the researchers found that neither magnesium nor calcium serum concentrations were viable predictors of hospitalization duration or survival rates postoperatively.

Conclusion

Based on the data collected and analyzed, it was concluded that hypomagnesemia and hypocalcemia were prevalent, particularly in horses with strangulating intestinal lesions and ileus during the perioperative period. Interestingly, serum concentrations of tMg2+ and tCa2+ were deemed less sensitive than iMg2+ and iCa2+ in detecting horses with hypomagnesemia and hypocalcemia.