Gross pathology of herons and egrets (family Ardeidae) at a wildlife rehabilitation centre in Northern California

Abstract

Gross necropsies were performed on all herons and egrets (family Ardeidae) that died or were euthanized at a wildlife rehabilitation centre in Fairfield, California, over a six-week period in the summer of 2018 (n = 145). Of the animals necropsied, 108 (74.5%) were euthanized and 37 (25.5%) died. Common reasons for euthanasia were trauma (n = 24), MBD (n = 39) and non-specific signs such as hypothermia and obtundation that persisted in the face of medical and supportive care (n = 32). MBD was found both in birds at admission (n = 9) and later in care (n = 34), despite calcium supplementation to correct calcium:phosphorus ratios of foods. Feeder fish were suspected to be deficient in vitamin D, and supplementation successfully reduced the development of this problem during the care later in the season. Nematodes of the genus Eustrongylides were found in the coelomic cavities of 43 (30%) birds. High burdens were often accompanied by coelomitis and abscessation involving internal organs. Visceral gout (n = 10) and intestinal perforation (n = 4) were both strongly associated with the administration of meloxicam. These findings suggest meloxicam should be used with caution in these species. Other less common findings included septic arthritis, intestinal perforation and hepatomegaly. This study describes common gross pathological findings of herons and egrets in a wildlife rehabilitation centre in California and demonstrates the utility of gross necropsies in determining cause of death when more advanced post-mortem diagnostics are unavailable