Objective—To compare the efficacy of calcium disodium
EDTA (CaNa2EDTA) and meso-2,3-dimercaptosuccinic
acid (DMSA) in reducing concentrations of
lead in selected tissues for use in treatment of calves
with experimentally induced lead toxicosis.
Animals—19 sexually intact male Holstein calves
that weighed 35 to 60 kg.
Procedure—Calves were randomly assigned to 1 of 5
treatment groups: group 1, control calves; group 2,
lead only; group 3, lead and EDTA; group 4, lead and
DMSA; and group 5, lead, EDTA, and DMSA. Calves
in groups 2 to 5 were dosed daily with lead (5 mg/kg,
PO) for 10 days. Doses of EDTA (100 mg/kg) and
DMSA (25 mg/kg) were administered IV once daily for
4 consecutive days beginning on day 11. Effects of the
chelators on lead concentrations in the liver, kidneys,
testes, muscles, bones, and brain were compared
among the various groups.
Results—Compared with the effects of EDTA, DMSA
greatly reduced lead concentrations in renal and
hepatic tissues. We did not detect significant differences
for the effects of EDTA or DMSA on lead concentrations
in the testes; there was an adverse interaction
of EDTA with DMSA that caused an increase in
lead concentrations in the testes.
Conclusions and Clinical Relevance—DMSA is
much more effective than EDTA in removing lead
from renal and hepatic tissues in calves. Use of
DMSA in calves with lead intoxication appears to be a
viable treatment option. Combining DMSA and EDTA
as a treatment modality in calves did not offer any
advantages. (Am J Vet Res 2003;64:672–676)