Cats discriminate between cholecalciferol and ergocalciferol

Area of Science:

• Veterinary Medicine
• Nutritional Science
• Biochemistry

Background:

• Vitamin D is crucial for calcium homeostasis and bone health in cats.
• Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) are common forms of vitamin D supplementation.
• Understanding the differential efficacy of these vitamin D forms in cats is important for appropriate nutritional management.

Purpose of the Study:

• To compare the efficacy of ergocalciferol and cholecalciferol in elevating plasma vitamin D metabolites in cats.
• To investigate the pharmacokinetic profiles of ergocalciferol and cholecalciferol in feline subjects.
• To determine the relative utilization efficiency of ergocalciferol versus cholecalciferol in cats.

Main Methods:

• Oral and parenteral administration of ergocalciferol and cholecalciferol to cats.
• Measurement of plasma concentrations of vitamin D and its metabolites (25-hydroxyvitamin D2 and 25-hydroxyvitamin D3).
• Analysis of peak concentrations, time to peak, and area under the curve for plasma metabolites.

Main Results:

• Cholecalciferol administration led to rapid increases and declines in plasma concentrations, while 25-hydroxyvitamin D showed a sustained elevation.
• Peak plasma concentrations of cholecalciferol were more than double those of ergocalciferol when administered orally.
• Parenteral administration and dietary inclusion showed higher 25-hydroxyvitamin D3 levels than 25-hydroxyvitamin D2, indicating discrimination against ergocalciferol.

Conclusions:

• Cats demonstrate a clear discrimination against ergocalciferol compared to cholecalciferol.
• The efficiency of ergocalciferol utilization for maintaining plasma 25-hydroxyvitamin D concentrations is approximately 70% of that of cholecalciferol.
• Differences in binding protein affinity for vitamin D metabolites likely explain the observed discrimination in cats.