Effects of surgery on free and total 25 hydroxyvitamin D concentrations in dogs.

BACKGROUND: It is unclear whether a low total 25(OH)D concentration is a cause or consequence of illnesses. To address this knowledge gap, studies measuring free and total 25(OH)D during the evolution and resolution of an inflammatory process are required.

OBJECTIVES: Serum total and free 25(OH)D concentrations would transiently decline after cruciate surgery in dogs.

ANIMALS: Seventeen client-owned dogs with a spontaneous cranial cruciate ligament rupture (CCLR).

METHODS: A longitudinal cohort study involving the measurement of serum concentrations of total and free 25(OH)D, total calcium, creatinine, albumin, phosphate, C-reactive protein and plasma ionized calcium, at 1 day before and a median time of 1 and 60 days after surgical treatment of CCLR.

RESULTS: Median serum concentrations of total 25(OH)D before surgery (80.3 nmoL/L [range, 43.5-137.3]) significantly declined immediately after surgery; (64.8 nmoL/L [range, 36.3-116.5] 1 day after surgery, P < .005) before increasing to become nonsignificantly different from concentrations before surgery at day 60 after surgery (median 78.0 nmoL/L [range, 24.2-115.8], P = .14). In contrast, median free 25(OH)D concentrations before surgery (7.6 pg/mL [range, 3.8-12.2]) significantly increased immediately after surgery (9.2 pg/mL [range, 5.2-15.7], P < .05) before declining to become nonsignificantly different from before surgery concentrations at day 60 after surgery (median 6.2 pg/mL [range, 4.0-15.8], P = .37).

CONCLUSION AND CLINICAL IMPORTANCE: This study reveals the difficulties of assessing vitamin D status in dogs following elective surgery.