Study of prognostic potential of Red Cell Distribution Width (RDW) in hepato-renal diseases of canines

Introduction

Red blood cell distribution width (RDW) is a quantitative measure of variation in erythrocyte size and is a reliable indicator of anisocytosis. RDW is the standard deviation (SD) of the red cell volume divided by the mean corpuscular volume (MCV). RDW reflects the heterogeneity in circulating erythrocyte volume. An alteration in RDW can be seen in variety of conditions that causes significant increased number of immature RBCs in circulation, such as regenerative anaemias or inflammatory processes in bone marrow stimulating the hematopoietic cells (Rogiers et al., 1992; Neiger et al., 2002; Zurauskaite et al., 2018) [1,2] . Numerous pathological conditions are associated with elevated RDW levels with or without anemia such as renal, hepatic, cardiorespiratory disease, pancreatic, vascular, neoplastic, endocrine, bone marrow disorders, nutritional deficiencies, chronic or acute systemic inflammation, sepsis, and the use of drugs like nebivolol and metoprolol (Salvagno et al., 2015; Martinez et al., 2019) [4,3] . Furthermore, elevated RDW value could be used as reliable predictor of mortality in heart failure, hematological malignancies, acute pancreatitis, kidney disease, obstructive jaundice and community-acquired pneumonia induced by cancer, and sepsis or septic shock (Salvagno et al., 2015) [4] . RDW has been extensively researched as a readily available quantitative marker of erythrocyte anisocytosis in human patients (Qin et al., 2017) [5] . Higher RDW readings could be due to various physiological and pathological conditions (Martinez et al., 2019) [3] . The prominent physiological causes includes ageing (Cheng et al., 2004; Patel et al., 2004) [6] , pregnancy (Shehata et al., 1998) [7] , ethnicity (Saxena et al., 1990) [8] and moderate physical exercise (Lippi et al., 2012; Salvagno et al., 2015) [9,4] . The previous studies have demonstrated the direct association between high RDW and risk of liver disease, cardiovascular dis ease, kidney disease and metabolic syndrome (Montagnana et al., 2011; Hu et al., 2013; Laufer et al., 2015) [11,12,10] . Besides, RDW, another most commonly used index to ascertain the degree of anisocytosis is the mean corpuscular volume (MCV), which is deduced using volume and globular erythrocyte counts. However, small changes in the volume of RBCs may not have singificant alteration in MCV, therefore a large percentage of cells with modified volume are required to produce appreciable changes in the MCV and anisocytosis in blood picture (Ferreira et al., 2009) [13] . The RDW along mean corpuscular volume (MCV) has also been used in subclassification of anemias (Salvagno et al., 2015) [4] . The findings of study suggested that the increased MCV with unaltered RDW could be due to aplastic anemia and chronic liver disease whereas the increased RDW with unaltered MVC are associated with iron, cobalamin, folate deficiency or chronic hepatobiliary disease. The studies on RDW as tool of diagnosis and prognosis in canines are scarcely available. Further, the microcytosis with elevated RDW are common findings in healthy dogs of some breeds like Akita and Hokkaido, Japanese shiba. Similarly, elevated RDW with macrocytosis have been reported in toy and miniature poodles (Perret et al., 2001; Aniolek et al., 2017) [15,14] . Breeds like Alaskan malamutes, Drentse partridge, and miniature schnauzers with hereditary symptomatic and asymptomatic stomatocytosis have been documented to have increased RDW (Bonfanti et al., 2004) [16] . In another study, the higher RDW was found associated with a higher risk of mortality in dogs (Ludwik et al., 2022) [17] . The limited availability of studies on RDW in canines, the present study was designed with objective to measure the RDW alteration in canine patients suffering from hepatic and renal diseases, and to evaluate if any prognostic association exists with RDW.

Materials and methods

Animals

Canines patients presented to the Referral Veterinary Polyclinic, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly-243122, Uttar Pradesh with the symptoms suggestive of liver and kindley disease were enrolled in the present study. The sampling and other diagnostic modalities used in this study has prior client consent. Sampling: The 2 ml of whole blood was aseptically collected from cephalic venipuncture. The 500 µl was placed in EDTA tubes and 1.5 ml in serum collection tube. The serum tube was allowed to clot followed by centrifugation @ 3000 rpm and serum were stored at -20°C until used for serum chemistry. The EDTA whole blood samples were immediately subjected to complete blood count using hematology analyzer (Celltac α, Nihon Kohden, Japan). The RDW were obtained as part of heamatology analaysis and expressed as percentage mean (standard deviation) of the measurement of size variability of the red blood cells.

Screening for hepatic and renal disease

The collected serum samples were analyzed for performing the serum chemistry. The serum glutamic pyruvic transaminase (SGPT), blood urea nitrogen (BUN), creatinine, total bilirubin (TB), direct bilirubin (DB), indirect bilirubin (IB), total protein (TP) and albumin (Alb) were estimated using commercially available kits (Tulip Diagnostic Pvt Ltd).

Ultrasonography (USG)

The patients showing alteration in serum biochemical parameteres were subjected to ultrasonographic imaging (Acuson X 300, Siemens, USA) using 5 MHz curvilinear probe for confirmation of heaptic and renal pathologies.

Data analysis

The findings of study were analyzed by Pearson correlation coefficient and one way ANNOVA using statistical analysis package IBM SPSS 20 (SPSS, Science, Chicago, USA). The multiple comparisons between the groups was done by using Tukey test at 5% level of significance.

Results and discussion

RDW is inexpensive and readily available information as part of a complete cell count investigations. The RDW has been proved to be a quantitative marker of anisocytosis in RBCs. Besides, its role as supplemental diagnostic marker in anaemia, the prognostic potential of RDW in range of diseases is well appreciated in human patients. However, the studies on canine patients are scarcely available in literature. The alteration in RDW may have a stronger prognostic value than other costly and clinically inaccessible indicators. Therefore, the present study was hypothesized to study the prognostic significance of RDW for diagnosis of hepatic and renal diseases of canines.

In the present study, the renal (n = 11), hepatic disease (n = 11) and 6 healthy canines were enrolled for comparison. The hepatic group consists of Labrador Retriver (n = 5), German Shephered (n = 2) and Naplean Mastiff, Pitbull, Pomerarian and Non-discript (n = 1 each). The renal diseases were confirmed in 8 males and 3 females of the study. Breed distribution showed highest number of cases in Labrador Retriver (n = 5) followed by German Shephered (n = 2) and Naplean Mastiff, Pitbull, Pomerarian and Non-discript (n = 1 each). Similarly, the hepatic disease group breed distribution showed highest number of cases in Labrador Retriver (n = 6) followed by Pomerarian and Non-discript (n = 2 each) and 1 case in German Shephered. A total of 6 males and 5 females were found affacted with heaptic disease out of 11 canines enrolled in the study. In the healthy control group all animals were male German Shephered breed with median age of 3.75 years (range 3-4.5 years). The median age in hepatic disease group was 6.4 years (range: 3-10 years) and renal disease group was 6.8 years (range: 2.5-12 years). The marked ultrasosnographic features in hepatic diseases group were hepatic enlargements, chronic hepatic fibrosis with and without ascites, and cholecystohepatitis with spleenitis. In the renal diseases group, the prominent ultrasonographic findings included markedly reduced cortico-medullary differentiation, markedly thickened, granular and hyperechoic renal cortex and dilation in renal pelvis. The five canines were diagnosed with chronic kindey disease and six were having glomerulonephritis, ureteral obstruction and pylonephritis and acute kidney injury. The findings of hemato-biochemical changes in hepatic, renal and healthy groups are summarized in table-1. The mean RDW value in healthy, hepatic and kidney diseases groups were found as 12.37 ± 0.41% (range-11.4 to 13.4%), 17.40 ± 0.94% (range-13.1 to 23.6%) and 14.24 ± 0.56% (range-12.5 to 17.8%), respectively. There was a statistically significant (P ≤ 0.0021) difference in RDW values between hepatic and renal disease group. When compared to the control group, RDW value was significantly increased (p < 0.05) in the dogs diagnosed with hepatic disease. In present study, a significant increase in RDW value was observed in hepatic disease group compared to healthy control, which is in consistent with the findings of Hu et al. (2013) [12] and Martinez et al. (2019) [3] . The exact underlying mechanism of the increased RDW values in hepatic disease is still unclear, however, several possible explanations are documented such as inflammation of hepatic parenchyma leading to release of the inflammatory cytokines adversely affecting the erythrocyte maturation and promoting the release of immature reticulocytes into the peripheral circulation (Pierce et al., 2005; Cengiz et al., 2013) [19,18] . Similar association between RDW and inflammatory response has been reported by Lippi et al. (2009) [20] and Patel et al. (2010) [21] . Zhao et al. (2014) [22] also reported the elevated RDW levels due to oxidative stress and inflammation in canine. The increased RDW was also found associated with lower concentration of folic acid in hepatic disease patients (Hu et al., 2013) [12] . Folic acid deficiency may result in impaired erythropoisis and erythrocyte maturation leading to increased heterogeneity of erythrocytes. Further, alteration in RDW is also associated with portal hypertension commonly reported in hepatic disease could cause hypersplenism resulting in accelerated erythrocytes destruction and release of immature, larger RBCs from bone marrow into the circulation (Evans, 1991; Cardenas and Gines, 2009) [24, 23] .

In hepatic diseases, compared to conventional prognostic indicators such as albumin, A/G ratio, bilirubin (TB, DB and IB) and platelets, the RDW could serve as more reliable indicator possibly due to limitation of short half-lives for serum bilirubin, platelet and albumin as 10 h, 4 days and 10 -20 days, respectively (Hu et al., 2013) [12] . Whereas the lifespan of RBCs are 110-115 days. Therefore, RDW may reflects the hepatic disease status for longer period whereas the conventional parameters reflects current status (Adili et al., 2014) [25] . The RDW value in renal disease group was also found to be increased as compared to the healthy control group but this increase was statistically insignificant (Table -1). RDW value in renal disease group of present study was found non significantly increased as compared to hepatic and healthy groups. Contrary to findings of the present study Martinez et al. (2019) [3] has reported significantly higher RDW values in the dogs with renal diseases. The possible reason of non-significant elevation of RDW in present study could be inclusion of canines in early stages of renal diseases along with chronic kidney disease. In present study, only 5 canines were having significantly evelated BUN and creatitine whereas, the remaining 6 canines were having mild to moderate elevation of serum BUN and creatinine concentration. Despite increased RDW values in both the diseased groups, the MCV values of all the groups were within the reference range (Table -1). The previous studies on RDW have suggested that the RDW values should not be interpreted separately. The alternation in RDW with MCV can provide more useful prognostic information than the RDW alone. In the present study, regardless of significantly increased RDW values, MCV values were found within the reference range. Martinez et al. (2019) [3] also reported the normal MCV values with higher RDW in early cobalamin, iron, or folate deficiency and chronic hepatobiliary diseases. Further, the increased RDW and decreased MCV are also reported in haemorrhagic diseases (Arslan et al., 2017) [26] . The overall correlation of RDW and heamato-biochemical parameters of this study is presented in correlation matrix (Table 2). The correlation between Hb and PCV was 0.606 (P ≤ 0.01) and Hb and TEC was 0.53 (P ≤ 0.01). The association between Hb and various parameters such as MCV, MCH, platelets, IB, TP and Alb was positive but nonsignificant. The non significant correlation was also found between Hb and MCHC, RDW, TLC, SGPT, TB, DB, Globulin, creatitine and BUN. The association between PCV and TEC was significant (r = 0.89, P ≤ 0.01) however the association between PCV and other hemato-biochemical parameters of study remain non-significant. The associations of TEC with other hemato-biochemical parameters of study also remain non-significant. The correlation between MCV and MCH was positive and significant (r = 0.594, P ≤ 0.01) and with MCHC was negative but significant (r = -0.586, P ≤ 0.05). The correlation between RDW and SGPT was significant (r = 0.394, P ≤ 0.05). The correlation of TB with DB was positive and significant (r = 0.783, P ≤ 0.01) while the correlation of DB with IB was also positive and significant (r = 0.500, P ≤ 0.05). The correlation of IB and BUN was 0.480 (P ≤ 0.05). The significant positive corrrelation (r = 0.52, P ≤ 0.01) was observed between Alb and TP. The correlation between BUN and TB ( r = 0.491, P ≤ 0.05), BUN and IB (r = 0.480, P ≤ 0.05) and BUN and creatitine (r = 0.727, P ≤ 0.01) was positive and significant. There was moderate but significant positive correlation between RDW and SGPT (r = 0.394) and a moderate negative correlation was found between RDW and PCV (r= -0.309) and TP (r= -0.323). There were no correlation between RDW and other hematobiochemical parameters (Table 3 andTable 4). In the hepatic diseases group, the RDW has significant but negatively correlated ((r = 0610, P ≤ 0.05) with Hb. However, no significant correlation was found with RDW and other parameters in hepatic and renal disease groups (Table 3 andTable 4). The correlation data of the present study showed moderate but significant positive correlation between RDW and SGPT and a moderate negative correlation between RDW and PCV and TP. The RDW was reported to be a good predictor of hepatic fibrosis and showed significant association between RDW with SGPT and serum proteins (Xu et al., 2015) [27] . Further, in hepatic diseases group of this study, the RDW has significant but innegative correlation with Hb. Similar findings were also reported by Chen et al., (2013) [28] . The other hematobiochemical parameters of the study did not show correlation with RDW.

Conclusion

The findings of the present study suggested that the increased RDW could be used as useful supplemental information along with standard biochemical markers of hepatic and renal diseases. The author concludes that RDW may also be proved useful prognostic marker in monitoring the therapeutic outcomes after suitable studies in canine patients.

Acknowledgement

AcknowledgementThe authors sincerely thank the Director, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, for providing the necessary infrastructure for the study.

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31. How to cite this article: Bhagirathi, Chandra P, Rana M, Jagtap H, Verma A, Kant R. Study of prognostic potential of Red Cell Distribution Width (RDW) in hepato-renal diseases of canines. International Journal of Veterinary Sciences and Animal Husbandry. 2026;11(9):162-167. doi: https://www.doi.org/10.22 271/veterinary.2026.v11.i9c.3805