Serum vitamin D concentrations in hospitalized critically ill dogs

Abstract

Hypovitaminosis D has been extensively documented in critically ill humans. However, whether or not critically ill dogs have alterations in vitamin D concentrations remains unconfirmed. The primary aims of our study were to compare serum 25-hydroxycholecalciferol [25(OH)D] concentrations in critically ill dogs with healthy control dogs, determine the prognostic utility of serum 25(OH)D concentration as a biomarker in critically ill dogs, and to assess if serum 25(OH)D concentrations in critically ill dogs are associated with length of stay in the intensive care unit or illness severity. Serum concentrations of 25(OH)D together with a range of other clinical, biochemical, and hematological parameters, were measured in 99 dogs within 24 hours of admission to the Intensive Care Unit (ICU). Critically ill dogs (P = 0.001) and dogs with sepsis (P = 0.002) had significantly lower serum 25(OH)D concentrations compared to healthy control dogs. In addition, serum 25(OH)D concentration was an independent predictor of in-hospital and 30 day survival. Using a cut-off of 33 ng/mL, serum 25(OH)D concentrations had excellent sensitivity (0.94; 95% CI, 0.71-1.00), but poor specificity (0.41; 95% CI, 0.31-0.53) for detection of survival. Serum 25(OH)D concentrations were inversely associated with acute patient physiologic and laboratory evaluation (APPLE) fast score but were not associated with ICU length of stay. Hospitalized dogs with critical illness have decreased serum 25(OH)D concentrations compared to healthy dogs and can be used to predict survival in this cohort.

Fig 1. Box and whiskers plot comparing serum 25(OH)D concentrations in critically ill dogs and healthy control dogs.

The boxes represent the 25th and 75th quartiles with the horizontal line representing the median. The whiskers represent the range of the data. The black circles represent results for individual dogs. Healthy control dogs (n = 17) had significantly greater serum 25(OH)D concentration than critically ill dogs (n = 99).

Fig 2. Box and whiskers plot comparing serum 25(OH)D concentrations in survivor and non-survivor critically ill dogs.

The boxes represent the 25th and 75th quartiles with the horizontal line representing the median. The whiskers represent the range of the data. The black circles represent results for individual dogs. (A) Dogs that survived (n = 82) to discharge had significantly greater serum 25(OH)D concentration than non-survivors (n = 17). (B) Dogs that were alive (n = 23) 30 days after discharge had significantly greater serum 25(OH)D concentrations than non-survivors (n = 70).

Fig 3. Receiver-operating characteristic (ROC) curve and dot plot comparing the diagnostic sensitivity and 1-specificity of serum 25(OH)D concentration for determining survival in the intensive care unit.

(A) The diagonal red line represents the reference line (B) The horizontal red line represents the optimal serum 25(OH)D concentration cutoff of 33 ng/ml.

Fig 4. Receiver-operating characteristic (ROC) curve and dot plot comparing the diagnostic sensitivity and 1-specificity of serum 25(OH)D concentration for determining survival 30 days after discharge.

(A) The diagonal red line represents the reference line. (B) The horizontal red line represents the optimal serum 25(OH)D concentration cutoff of 30 ng/ml.

Fig 5. Box and whiskers plot comparing serum 25(OH)D concentrations in dogs that stayed ≤ 3 days in the intensive care unit to those that stayed > 3 days.

The boxes represent the 25th and 75th quartiles with the horizontal line representing the median. The whiskers represent the range of the data. There was not a significant difference in serum 25(OH)D concentrations in dogs that stayed ≤ 3 days (n = 42) and those that stayed > 3 days (n = 40, P = 0.14).

Fig 6. Correlation between serum 25(OH)D concentration and APPLE fast score.

Serum 25(OH)D concentrations had a weak, inverse, yet significant correlation with APPLE fast scores.

Fig 7. Box and whiskers plot comparing serum 25(OH)D concentrations in dogs with sepsis and healthy control dogs.

The boxes represent the 25th and 75th quartiles with the horizontal line representing the median. The whiskers represent the range of the data. The black circles represent results for individual dogs. Healthy control dogs (n = 17) had significantly greater serum 25(OH)D concentration than dogs with sepsis (n = 17).