Reference intervals and age-related changes for venous biochemical, hematological, electrolytic, and blood gas variables using a point of care analyzer in 68 puppies

Objective: To determine the reference interval for various venous analyte concentrations using a point-of-care (POC) analyzer in healthy, 4-84-day-old puppies and identify any age-specific variations in the values as compared with adults. Design: A prospective cohort study. Setting: University teaching hospital. Animals: Clinically healthy dogs; 68 puppies and 30 adults. Measurements and Main Results: Samples were collected by jugular venipuncture from 68 clinically healthy puppies at 4, 10, 12, 16, 28, 70, 77, and 84 days of age and once each from 30 clinically healthy adult dogs. Blood samples (n = 287) were analyzed within 5 minutes of collection using an automated POC analyzer. Reference intervals for puppies at various ages were estimated using a bootstrap sampling approach. The analytes that were closest to the adult values were pH and bicarbonate. On days 4 and 10 the pH for puppies was higher than the adults while the HCO₃ was higher than the adults only on day 4. HCT on day 4 approximated adult values but fell to a nadir on day 28 before rising toward adult levels. At all time points, sodium, chloride, and ionized magnesium concentrations were lower than adult values, and potassium and ionized calcium were higher than adult values. Glucose was similar to adult values on day 4 but was above adult values at all other time points. Blood urea nitrogen (BUN) was higher in puppies until day 28 when it became lower than in adults. BUN levels remained lower than adults through day 84. Conclusions: Variations exist between puppies and adults for venous POC analyzer results. Adult reference intervals should not be used for puppies as this might cause misinterpretation of the results.