Serum concentration of 25 (OH) vitamin D in healthy dogs: factors as age, sex, and diet

The main source of vitamin D in dogs is their diet. Information on vitamin D in dogs and on factors that may influence the serum concentration of 25(OH)D are still scarce. This study aimed at determining serum 25(OH)D values in healthy dogs and evaluating its association with factors such as sex, age, and diet. Blood samples were collected from healthy intact male and female dogs divided into two groups: (G1) 30 dogs (Beagles), 15 adults and 15 puppies, receiving standardized diet; (G2) 29 dogs of different breeds, adults, receiving varied diets. The 25(OH)D was analyzed by the chemiluminescence method. Serum levels of 25(OH)D are not associated with sex, but the concentration is lower in puppies (30.6 ng/mL) than in adults (34.9 ng/mL) (G1), P < 0.05. There was no difference between the types of diet: commercial food (40.6 ng/mL), and the combination of commercial and homemade food (36.0 ng/mL), P = 0.2. The concentration of 25(OH)D may not be directly associated with vitamin D intake (G1), P = 0.08, which emphasizes the importance of considering and investigating multiple variables that may influence the availability of vitamin D in their circulation.