ABSTRACT
Anaemia is one of the most clinically encountered conditions in animals and humans. It continues to be a global public health problem, affecting both developing and developed countries with major consequences for human and animal health as well as social and economic development. The objective of this study was to develop and test a rat model for experimental studies on sub-acute blood loss anaemia. The study design was an experimental research and development protocol, made up of two experiments (1 and 2). Experiment 1 was for the development of the model while experiment 2 was for testing the developed model. A total of 162 albino rats of either sex, between the ages of 10 and 12 weeks weighing 130 – 250g were used for the study. In experiment 1, 130 rats were assigned at random, into thirteen groups of ten each (5 males & 5 females) labelled 1 to 13. Baseline values of the haematological parameters and serum protein were determined using standard procedures before the commencement of the study. Rats in group 1 were not bled and served as control. Blood loss was induced at specified periods of time for the remaining 12 groups using the orbital bleeding technique. At the end of the specified period of bleeding for each group, the haematological parameters and serum protein were re-assessed in order to select which group met the target of halving the RBC count, Hb and packed cell volume (PCV) with minimal stress, which is characteristic of sub-acute blood loss anaemia. In experiment 2, the selected group was tested using varied haematinics in 32 rats assigned at random into four groups labeled A to D: group A was the non-anaemic control, group B was the selected model treated with ferrous sulphate + folic acid + vitamin B-complex daily for 7 days, group C was the selected model treated with HB12® (haemoglobin syrup and vitamin B12) daily for 7 days and group D was the selected model not treated with haematinics. Data generated from all parameters assessed for each of the groups were compared using a one-way analyses of variance, and variant means were separated using the xv least significant difference. Results obtained pre and post-bleeding in experiment 1 were subjected to a t-test for paired samples. A significant difference was accepted at p < 0.05. The PCV, Hb, RBC counts of the rat groups that were bled (groups 2 – 13) decreased significantly (p < 0.05) after bleeding to varying degrees across the groups based on the volume of blood removed and the duration, except in the males of group 2 and 3 and females of group 9. The greatest percentage decrease in overall PCV, Hb and RBC counts was recorded in group 12 (42.4% for PCV, 48.1% for Hb and 44.4% for RBC count) and males in the group had significantly (p < 0.05) greater decreases than females. There was no significant changes (p > 0.05) in the PCV, Hb and RBC count of the unbled control group (group 1). The reticulocyte count of all the rat groups that were bled (groups 2-13) significantly (p < 0.05) increased after bleeding, with the rat groups bled daily having the highest increases. There were no significant (p > 0.05) changes in the reticulocyte count of the group 1 rats. The serum total proteins of rats in groups 9 and 13 were significantly higher (p < 0.05) after bleeding but those for rats in groups 5, 6 and 11 were significantly lower (p < 0.05) after bleeding. No significant changes (p > 0.05) were recorded in the serum total proteins of rats in groups 1, 2, 3, 4, 7, 8 and 12. The total white blood cell (WBC) counts of rats in groups 2, 3, 4, 7, 8, 9, 10 and 13 were significantly (p < 0.05) reduced after bleeding, but that of rats in groups 1, 5, 6, 11 and 12 did not significantly (p > 0.05) change. Rats in group 12 bled 2 ml/100 g b.w. every other day for 20 days topped all other groups in meeting the target of halving the PCV, Hb and RBC with minimal stress and were selected as the model for further testing in experiment 2. In experiment 2, the rats rendered anaemic by bleeding 2 ml/100 g b.w. every other day for 20 days and treated with two haematinics responded to treatment by normalization of their PCV, Hb, RBC and reticulocytes 6 – 9 days post-treatment. It was concluded that removal of 2 ml of xvi blood/100g b.w. from 10 – 12 weeks old rats every other day for 20 days is recommended for the induction of sub-acute blood loss anaemia in rats.