A preliminary study into the potential use of lithium in deer: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours

Abstract

Experiments were conducted to investigate the pharmacokinetic parameters of lithium in young (5-9 month old) red deer stags (Cervus elaphus) kept indoors following both acute and chronic oral administration of lithium chloride. Behavioural responses to chronic lithium therapy were also explored. Three experiments were carried out. The first experiment involved determining a dose response relationship between dose rate (acute, oral) and plasma lithium concentration. Dose rates of 0, 0.25, 0.5, 0.75, and 1.0 mmol LiCl/kg LW were administered in 200ml water using a drench gun, to 10 young red deer stags (two animals/ dose rate) on two different occasions and sequential blood samples were taken at 0, 2, 6, 12, 18, 24, 48, 72, 96, 120, 144, and 168 hours after dose administration. The resulting dose response relationship could be described by the following equation y = 0.949x - 0.03 (r³ = 0.96), where y = plasma lithium concentration (mmol/l) and x = dose rate (mmol LiCl I kg L W). In the second experiment 0, 0.5 and 0. 7 mmol Li Cl/kg L W/d were administered for six days in the drinking water of young red deer stags (three animals per dose rate). The concentration in the drinking water for those animals receiving lithium chloride varied from 8.9 - 10.3 mmol LiCl/l depending on animal liveweight and dose rate. Resulting plasma lithium concentrations (0, 0.62, and 0.86 mmol/l) were within 11 % of those predicted based on the dose response relationship described above and associated flow rates. Mean VFI (g DM/DOM/ kg w°·⁷⁵ ) and water intake (ml/kg) was not significantly different between dose rates. A third experiment involved a control and chronic dose (0.0 and 0.6 mmol Li Cl/kg L W/d) of lithium chloride administered int he drinking water of two stag groups (n=l0) for 31 days. The concentration of lithium chloride in the drinking water of the +Li group was 11 .6 mmol LiCl/l but varied according to total weekly liveweight change. Mean plasma lithium concentration of the +Li group (0.78 ±0.04 mmol/l) was within 6 % of that expected. VFI and water intake were reduced in the +Li group compared to the control group after one and two weeks of therapy (p<0.05), respectively, however this difference was recovered by the last week of the experiment. The depression in VFI resulted in 4% less L WG in lithium treated stags compared to the control group but this was not significant (252 versus 263 g/d respectively). Lithium treatment changed diet preference in deer, lithium treated stags selected chaff as 40% of their total diet, more than double the proportion selected by control stags (18%). Mean right pedicle length was not significantly different between the stag groups. Lithium was found to modify behaviour in young red deer stags. Treated stags moved more readily out of, and explored areas of yards, with 60% completing a 'maze' course compared to 10% for the control group. Lithium did not reduce aggression when incidences of aggressive behaviour directed at unfamiliar animals were recorded in both the control and treatment groups and no difference in reaction to handling was observed between groups, however these outcomes may be different in adult rutting stags where levels of aggression are higher. In conclusion, self-medication, through administration of a chronic daily dose of lithium chloride in drinking water can be used to achieve stable and predictable concentrations of lithium in the blood plasma of young deer. On the basis of this study the use of lithium to modify behaviour in mature stags during the breeding season may have potential.