Diurnal variations in canine hematological parameters after commercial feed feeding

Abstract

Complete blood count (CBC) is the evaluation of blood cells, which provides resourceful information. Considering that inadequate fasting time is the most common pre-analytical error in laboratory diagnosis and is associated with lipemia in blood samples, which has not yet been adequately investigated in dogs, this study aimed to assess diurnal postprandial changes in the CBC of healthy dogs fed with industrialized feed. Eighteen clinically healthy dogs aged 2-6 years and weighing over 6 kg were enrolled in the study. All dogs received “Premium” industrialized feed every 12 hours. Blood was collected after a 12-hour fasting period at 6:00 am (baseline), followed by feeding and new blood samples collected hourly for the next 11 consecutive hours. Red blood cell (RBC) counts, red cell distribution width (RDW), white blood cell (WBC) counts, platelets, mean platelet volume (MPV) and hemoglobin were obtained using an automated veterinary cell counter. Hematocrit (HTC) was determined by Strumia's microcapillary method, differential leukocyte count was performed on hematological dye-stained blood smears and total plasma protein (TPP) was determined using refractometry. Variables were tested for normality and differences were considered significant when p < 0.05. A statistically significant decrease was observed in the erythrogram from 2 h for RBC and hemoglobin, from 3 h for HTC and from 4 h for MCV, persisting until the end of 11 hours. There was no change in MCHC and RDW. Regarding the leukogram, a significant increase in WBC was observed from 2 to 7 h, due to the increase in segmented neutrophils 2 to 8 h following feeding. Lymphocyte counts decreased significantly at 2 and 6 h following feeding. No alteration was observed in eosinophil, basophil, monocyte and platelet counts, as well as in MPV. From 5 h to 11 h after feeding, a significant decrease was seen on TPP. However, changes in hematological parameters did not exceed reference ranges for the canine species. Feeding dogs with industrialized feed caused statistically significant changes in erythrogram, leukogram and plasma protein content. While these changes do not seem to exceed reference values for the species in healthy animals, caution is warranted for sick animals with borderline values, in which these changes might be clinically important depending on the pathologic process.

Effect of food intake on complete blood count of healthy dogs

“…In humans with samples also obtained at the same day before and after the meal, the decrease seen on these parameters was attributed to fluid intake during the meal (LIPPI et al, 2010, p. 98). As pointed out by Costa et al (2020Costa et al ( , p. 2226, the reduction of the RBC series concentration in dogs following feeding could also be related to water intake. In the present study, the analysis was carried out in a timely manner at the same time of the day, with no interference from water intake by successive collections at the same day or the same effect of the circadian cycle, which therefore explains the discrepancies.…”

“…Red blood cells concentration and therefore HCT were not influenced by feeding. Previous studies in dogs, with blood samples obtained during a 12 h period after feeding reported a decrease in these parameters and hemoglobin since 1 h following the meal (COSTA et al, 2020(COSTA et al, , p. 2224. In humans with samples also obtained at the same day before and after the meal, the decrease seen on these parameters was attributed to fluid intake during the meal (LIPPI et al, 2010, p. 98).…”

“…MCV and RDW were unaffected by the postprandial condition in our study 3 h following feeding. Costa et al (2020Costa et al ( , p. 2227, observed a decrease in MCV 4 h following feeding in dogs. Korbonits et al (2007, p. 162) explain that feeding leads to an increase in plasma osmotic pressure, causing RBC to lose fluid and thus reducing their size, leading to a decrease in MCV values.…”

“…Biochemical analysis was performed as part of a health screening for inclusion in this study, according to previously published methodology (COSTA et al, 2020, p. 2222, SILVA, et al, 2019).…”

“…To date, studies that assess the isolated effect of feeding on postprandial hypertriglyceridemia peak in dogs remain scarce. Costa et al (2020Costa et al ( , p. 2224) observed an increase in red blood cells concentration (RBC), hemoglobin, hematocrit (HCT) and mean corpuscular volume (MCV) from as soon as 1 h following feeding in dogs, depending on the evaluated parameter. They also reported an increase in total leukocytes concentration due to increased segmented neutrophil count, in addition to decreased lymphocyte count at specific times following feeding with commercial ration.…”