Lead toxicity remains a significant cause of morbidity and mortality in wild California condor (Gymnogyps californianus) populations.3 Eleven free-ranging condors in Mexico were found to have elevated blood lead levels (>30 µg/dl) on annual health exam in 2007. All birds were relocated to the San Diego Zoo Safari Park. Due to logistical issues, the birds arrived at two different times; an initial group of five birds (early group) followed by a group of six birds (late group), three days later. All were clinically normal and of adult size (wt. range 7.4–10 kg). The treatment of lead intoxication for man and animals, including birds, is with the chelating agents calcium EDTA, DMSA or a combination of both.2,4,5 The daily treatment protocol consisted of 300 mg i.m. calcium EDTA (3M Pharmaceuticals, Northridge, CA 91324, USA); 300 mg p.o. meso-2,3-dimercaptosuccinic acid (DMSA, Bock Pharmacal, St. Louis, MO 63141, USA) and 300 ml s.c. isotonic fluids. The early group received 11 treatments over 13 days. One bird in this group was found dead on day 14. The late group had received 9 treatments in 11 days. All dual chelation treatment was stopped at this time. Necropsy revealed severe visceral and renal gout which has not been documented in condors with lead intoxication. There was no evidence of nephrosis or renal inclusion bodies which are diagnostic of lead poisoning in animals and man.1 These findings suggest this dual chelation protocol is nephrotoxic in California condors and should not be used to treat lead intoxication.
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2. Denver MC, Tell LA, Galey FD, Trupkiewicz JG, Kass PH. Comparison of two heavy metal chelators for treatment of lead toxicosis in cockatiels. Am J Vet Res. 2000;61(8):935–940.
3. Grantham J. California condor (Gymnogyps californianus) recovery program: population size and distribution. US Fish and Wildlife Service, Washington, D.C.; 2009.
4. Hoogesteijn AL, Raphael BL, Calle P, Cook R, Kollias G. Oral treatment of avian lead intoxication with meso-2,3-dimercaptosuccinic acid. J Zoo Wildlife Med. 2003;34(1):82–87.
5. Meldrum JB, Ko KW. Effects of calcium disodium EDTA and meso-2,30dimercaptosuccinic acid on tissue concentrations of lead for use in treatment of calves with experimentally induced lead toxicosis. Am J Vet Res. 2003;64:672–676.