Objective: To investigate age-related variations in results of hematologic and plasma biochemical tests performed on dogs of 2 common breeds.
Design: Prospective cohort study.
Animals: 34 Beagles and 44 Labrador Retrievers.
Procedure: Blood samples were collected throughout the dogs' lives; 589 samples were collected from the Beagles and 964 samples were collected from the Labrador Retrievers (age at the time of sample collection ranged from 22 days to 15 years). White blood cell and RBC counts; hemoglobin concentration; Hct; mean cell volume; mean cell hemoglobin concentration; alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase activities; and calcium, phosphorus, cholesterol, urea, protein, and albumin concentrations were measured.
Results: For all tests, there were significant effects of age on test results. There was a significant interaction between age and breed for all tests except hemoglobin, albumin, and phosphorus concentrations.
Conclusions and clinical relevance: Results suggested that there were age-related changes in hematologic and plasma biochemical test results in these 2 breeds of dogs. Changes were most evident during the first year of life, reflecting growth and maturation of the puppies. In some instances, values for puppies diverged markedly from those for adults, necessitating the use of age-specific reference ranges for the interpretation of clinical data.