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. (J Am Vet Med Assoc 2003;223:1436–1442)