Abstract
Limited knowledge is available on acute intoxication with environmental toxicants in birds. This experimental study determines features of acute caffeine intoxication and clinical outcome of different treatments in pigeons. The experiment was performed in three phases. Toxicity tests were performed in phases one and two while phase three was dedicated to comparative evaluation of fluid therapy and activated charcoal with or without diazepam and/or propranolol on clinical outcome of birds. Calculated LD50 was 366 mg kg(-1) although presence of regurgitation compromised the accuracy of LD50 application. The dose-response (death) curve was sharp with a slope of 8.41. Clinical signs included renal, neurological, gastrointestinal and respiratory symptoms that generally initiated in a few minutes and lasted for few hours. The approximate toxic dose (ATD) was 294 mg kg(-1). Serum and brain concentrations after administration of ATD followed a normal distribution in a range of 14.6 - 83.3 mg mL(-1) and 1.04 - 7.81 µg g(-1), respectively. Fluid therapy and activated charcoal with or without propranolol did not affect the clinical outcome of intoxicated birds while adding diazepam and intensive therapy with all of these agents even worsened the situation. In conclusion, caffeine is a potential source of intoxication in pigeons with a fast onset of clinical signs and a sharp increase in death rates by increasing doses. Symptoms are similar to mammals with prominent neurological signs although the ATD and serum concentrations are relatively high. Intensive therapy with above mentioned drugs is not recommended. Most birds survive after resolution of transient clinical signs without any special treatment.