Abstract
A diagnostic workup on an elderly tufted puffin (Fratercula cirrhata) with poor appetite, weakness, and mild ataxia showed an unexpectedly high plasma zinc level. Subsequent testing showed plasma zinc levels ranging from 2.7–5.6 ppm in all alcids in the same habitat (tufted puffins; common murres, Uria aalge; rhinoceros auklet, Cerorhinca monocerata). While species sensitivities vary, normal values for alcids were considered <2.0 ppm.1 Possible environmental sources were investigated, including foods, enrichment items, medications, seawater, algae, grasses, substrates, and habitat lining. Assays used inductively-coupled plasma mass spectrometry (ICP-MS). Extremely high levels of zinc were found in the pool substrate and blisters in the lining; a zinc coating had been applied to the habitat several decades previously to reduce corrosion.
Birds showing any morbidity were started on chelation therapy with dimercaptosuccinic acid (DMSA) at 35–50 mg/kg PO once daily (SID) to twice weekly. A dose of 50 mg/kg PO SID appeared most effective and resolved clinical signs in all birds treated. Mitigation efforts to reduce zinc ingestion included removing visible substrate from the environment and placing large rocks to reduce access to grit at the bottom of the habitat. There was an apparent reduction in the incidence of infectious diseases and no mortalities, although plasma zinc levels remained high.
The birds were removed from the habitat, all substrate was removed, and the pool lining was stripped by water-blasting and replaced with Tnemec paint. Birds that were on DMSA treatment when removed from the habitat showed improvement in their plasma zinc levels in 30 days. All birds were put on DMSA treatment after returning to the habitat to help clear zinc in their tissues. The birds are doing well, and health trends continue to be monitored.
Zinc exposure should be considered as a differential for alcids showing morbidity, including weakness and ataxia. Sources can be surprising in older animal habitats, and mitigation can be expensive. While it is routine at the Seattle Aquarium for veterinarians to be involved in construction plans, that was not the case in the 1990s, when zinc sensitivity of birds was known.2,3 This is a helpful reminder that veterinarians should review materials used in and around animal areas to reduce risks to animal health.
*Presenting author
Literature Cited
1. Puschner B, St. Leger J, Galey FD. Normal and toxic zinc concentrations in serum/plasma and liver of psittacines with respect to genus differences. J Vet Diagn Invest. 1999;11:522–527.
2. Reece RL, Dickson DB, Burrowes PJ. Zinc toxicity (new wire disease) in aviary birds. Aust Vet J. 1986;63:199.
3. Ritchie BW, Harrison GJ, Harrison LR. Avian Medicine: Principles and Application. Lake Worth: Wingers Publishing Inc.; 1994.