The osmotic fragilities of the red blood cells of 5 local dogs were
determined before and during sodium pentobarbitone anaesthesia using
different concentrations of sodium chloride solution. It was observed
that before the anaesthesia, the osmotic fragility decreased with
increasing concentration of sodium chloride solution, exhibiting a
sharp drop from a high (43%) at 0.5% to a low (19%) at 0.6%. Between
0.6 - 0.9% saline concentrations, the decrease in osmotic fragility was
rather more gradual. Under anaesthesia, the Osmotic Fragility curve was
shifted to the right of the pre-anaesthesia level. The pattern of
response was however basically the same- decreasing value with
increasing concentration of saline solution. The increases in osmotic
fragility values recorded during anaesthesia over those of the
pre-anaesthesia levels were significant (P < 0.05) for saline
concentrations 0.5% - 0.8%. The values of some other hematological
parameters such as the PCV, Hb, RBC and WBC only showed insignificant
decreases. It was concluded that veterinary practitioners employing
sodium pentobarbitone as anaesthetic agent should exercise more caution
than hitherto