MANAGEMENT OF SUSPECTED ZINC TOXICITY IN A MIXED ALCID COLLECTION (FRATERCULA CIRRHATA, URIA AALGE, AND CERORHINCA MONOCERATA).

Abstract

Two tufted puffins (Fratercula cirrhata) in a zoological collection of 10 birds presented with signs of weakness, ataxia, and decreased appetite. Diagnostic test results were supportive of zinc toxicosis. The remaining birds in the enclosure (four other tufted puffins, three common murres [Uria aalge], and one rhinoceros auklet [Cerorhinca monocerata]) were assessed, with plasma zinc levels ranging from 2.7 to 5.0 parts per million (ppm; 41.3-76.5 µmol/L). Possible environmental sources of zinc were investigated, including food, medications, seawater, plants, substrates, and habitat lining. Extremely high levels of zinc were found in the habitat sediment and lining (611,365 ppm at one site). A zinc coating had been applied to the habitat decades previously to reduce corrosion; the coating had eroded and contaminated grit was being ingested. All birds received chelation therapy with dimercaptosuccinic acid. A dosage of 50 mg/kg PO q24h appeared most effective and resolved all clinical signs. Long-term pulsatile use (months to years) was not associated with any complications. The birds were moved out of the habitat, the accessible lining was removed, the habitat was resealed, and any remaining sediment was flushed and removed prior to returning the birds. Morbidity and mortality in the group have decreased following this intervention. This case series highlights the importance of including veterinary professionals in the design and renovation plans for zoological enclosures.