CIRCANNUAL VARIATIONS IN BASE-LINE BLOOD VALUES OF DOGS

Forty-two hematological and biochemical variables routinely measured i n dogs as part of a preoperative protocol have been analyzed for circa nnual changes by analysis of variance (ANOVA) and single cosinor proce dures. Data were available from up to 489 adult mongrel dogs of both s exes studied on weekdays over a 5-year span (January 5, 1987 to Decemb er 18, 1991). Dogs were housed in individual cages at 24 +/- 1-degrees -C with dog chow and tap water available ad libitum and lights on betw een 06:00 and 18:00 h. A single blood sample/dog was collected by jugu lar venipuncture between 08:00 and 09:00 h and sent to a commercial la boratory for hematological and biochemical determinations. Data were a ssigned to date and time of sampling and analyzed for the effect of ti me of year by ANOVA (across 12 months and 4 seasons), and by the least -squares fit of a precise 1-year cosine. ANOVA and single cosinor desc ribed a significant circannual time effect and rhythm for the followin g: total leukocytes, lymphocytes, hemoglobin, mean corpuscular hemoglo bin (MCH), MCH concentration, red cell distribution width, mean platel et volume, creatinine, blood urea nitrogen (BUN), BUN/creatinine ratio , amylase, glucose, chloride, uric acid, direct bilirubin, total prote in, albumin, globulin, albumin/globulin ratio, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyltransferase, alanine aminotransfer ase (ALT), and aspartate aminotransferase (AST)/ALT ratio. A significa nt effect of season by ANOVA only was found for: Ca, Na, phosphorus, t otal bilirubin, hematocrit, mean corpuscular volume, and neutrophils. No significant time effect could be found at p less-than-or-equal-to 0 .05 by either statistical method for: K, Mg, Fe, cholesterol, triglyce rides, ASP, red blood cells, monocytes, eosinophils, basophils, or pla telets. Acrophases occurred for the most part in either the winter or summer.