Age-related changes in biochemical and hematologic variables in Borzoi and Beagle puppies from birth to 8 weeks

Nonspecific signs of illness and availability of only limited information about expected biochemical and hematologic values in puppies make formulation of a differential diagnosis challenging for veterinarians.

The objectives of this prospective study were to describe age-related changes in biochemical and hematologic variables in Borzoi and Beagle puppies from birth to 8 weeks and to compare results with adult reference intervals (RIs).

Biochemical and hematologic analytes in blood collected in heparin and EDTA from 31 clinically healthy puppies (21 Beagle and 10 Borzoi dogs) were measured or calculated each week from birth to 8 weeks of age. RIs were calculated using the parametric robust method after Box-Cox transformation.

There were no significant differences between values of puppies and adults for ALT activity, glucose concentration, MCHC, WBC count, and platelet count. Total protein concentration, RBC count, and HCT were lower and creatine kinase activity was higher in puppies of all ages compared with these variables in adults. Compared with adult RI, in puppies urea concentration was higher at birth and week 1, creatinine concentration was lower at weeks 1-5, ALP activity was higher at all weeks except for weeks 4 and 6, hemoglobin concentration was lower at weeks 1-8, MCV was higher at birth and week 1, and reticulocyte count was higher at all weeks except week 1. Statistically, mixed models accounted for evaluation of the same puppies each week and in most cases demonstrated an effect of age and sometimes breed. Some reference intervals should be used with caution owing to potential outliers. The 90% confidence intervals exceeded those recommended by the International Federation of Clinical Chemistry.

Clinicians should be aware of temporal changes in biochemical and hematologic values for puppies during the first 2 months of life to avoid misinterpretation of results.