Pathogenesis of lead shot poisoning in the mallard duck.

Adult mallard ducks were administered steel pellets to determine the rate of excretion from the gastrointestinal tract. In separate studies the ducks were administered 5 number 6 lead pellets. Birds were examined for clinical signs and sacrificed at given intervals over a 20 day period to assess changes in tissue structure and concentrations of lead with time. The above studies were conducted in 2 groups of ducks, fed a low or a high fiber diet. The rate of steel pellet excretion on birds on the low fiber diet decreased with an increase in pellet size. Pellet excretion was greatly reduced in birds fed the high fiber diet. Administration of lead shot resulted in the development of green diarrhea, anorexia and weakness. It also produced high concentrations of lead in the blood, kidney, liver and bone with lower concentrations in skeletal muscle. The major lesions were destruction of the mitotically active proventricular epithelium and medullary osteocytes, destruction of pectoral muscle cells and the presence of intranuclear inclusion bodies in the proximal tubular epithelium of the kidneys. Birds on the high fiber diet demonstrated more severe clinical signs and higher concentrations of lead in the tissues.