An assessment of the toxicity of parenteral treatment with copper EDTA and copper heptonate in sheep
The toxicity of 2 parenteral copper (Cu) supplements was investigated. Di-sodium copper ethylene diamino tetra acetate (Cu EDTA) and Cu heptonate were administered to sheep (n = 9) by a single subcutaneous injection at a concentration of 0,2, 1 and 2 mg Cu/kg each (Trial 1). Nine sheep were untreated and served as controls. The same treatments were applied to 2 sheep each (Trial 2) with the addition of 3 mg Cu/kg life body mass as Cu heptonate, and Cu heptonate administered intravenously at rates of 0,2, 0,4 and 0,6 mg Cu/kg live body mass. In Trial 1, 67% of the sheep treated with Cu EDTA at 2 mg Cu/kg live body mass died within 3 to 17 d after treatment, while no mortalities occurred in sheep where Cu heptonate was administered at the same dosage rate and even at 3 mg Cu/kg live body mass (P ≤ 0,01). Post-mortem examination suggested acute Cu toxicity in all cases. Liver Cu concentrations were markedly increased (P ≤ 0,05) by both supplements in groups of 3 treated sheep slaughtered over a 3-month period compared to control animals. The liver Cu concentrations of sheep that succumbed to Cu toxicity were within the normal range of 100 to 450 mg/kg DM. Results from Trial 2 suggested that the 2 sheep treated with 2 mg Cu/kg live body mass as Cu EDTA, experienced a haemolytic crisis between 5 and 11 d after treatment, resulting in the death of one of these sheep. The haemolytic crisis was characterised by a severe decrease in haemoglobin concentration and haematocrit. Sheep treated with Cu heptonate did not show any indications of similar complications, even when given 3 mg Cu/kg live body mass subcutaneously or 0,6 mg Cu/kg live body mass intravenously.