Secondary poisoning of non-target animals in an Ornithological Zoo in Galicia (NW Spain) with anticoagulant rodenticides: a case report

Abstract

The use of anticoagulants has increased in recent times as a method for controlling rodent populations. However, this increased use also provokes accidental and intentional ingestion for both animals and humans, triggering poisoning of non-target organisms. In the present report, a clinical case of secondary-poisoning of birds with anticoagulant rodenticides, which took place after a general rodenticide treatment in an Ornithological Zoological Park, is described. Three birds died as a result and samples were submitted to the Veterinary Hospital in Lugo (Galicia, NW Spain). After necropsy, samples of the birds, together with molluscs and faeces, were submitted to the Toxicology Unit of Caceres (Extremadura, W Spain) in order to detect possible chemicals. Results from HPLC analyses revealed the presence of the rodenticides difenacoum and brodifacoum. The present report shows that the risk of secondary exposure resulting from the scavenging of molluscs is likely to be significant. The potential routes of uptake by invertebrates include the consumption of rodent faeces, rodent carcases, the ingestion of soil-bound residues, and the direct consumption of poison baits.