Objective—To determine the pharmacokinetics and
toxic effects associated with IV administration of lithium
chloride (LiCl) to conscious healthy horses.
Animals—6 healthy Standardbred horses.
Procedure—Twenty 3-mmol boluses of LiCl (0.15
mmol/L) were injected IV at 3-minute intervals (total
dose, 60 mmol) during a 1-hour period. Blood samples
for measurement of serum lithium concentrations
were collected before injection and up to 24 hours
after injection. Behavioral and systemic toxic effects
of LiCl were also assessed.
Results—Lithium elimination could best be described
by a 3-compartment model for 5 of the 6 horses.
Mean peak serum concentration was 0.561 mmol/L
(range, 0.529 to 0.613 mmol/L), with actual measured
mean serum value of 0.575 mmol/L (range, 0.52 to
0.67 mmol/L) at 2.5 minutes after administration of the
last bolus. Half-life was 43.5 hours (range, 32 to 84
hours), and after 24 hours, mean serum lithium concentration
was 0.13 ± 0.05 mmol/L (range, 0.07 to
0.21 mmol/L). The 60-mmol dose of LiCl did not produce
significant differences in any measured hematologic
or biochemical variables, gastrointestinal motility,
or ECG variables evaluated during the study period.
Conclusions and Clinical Relevance—Distribution
of lithium best fit a 3-compartment model, and clearance
of the electrolyte was slow. Healthy horses
remained unaffected by LiCl at doses that exceeded
those required for determination of cardiac output.
Peak serum concentrations were less than steadystate
serum concentrations that reportedly cause
toxic effects in other species. (Am J Vet Res 2001;