PATHOLOGICAL FINDINGS IN LAYING HENS WHICH DIED DUE TO HEAT STRESS: CASE REPORT

Heat stress exerts a negative impact on the production indicators of animals and, can, threaten their lives. The aim of this study is to document and describe macroscopic, as well as microscopic findings in laying hens who died because of heat stress during the summer heat. This is a sample of 14 laying hens which were selected from mass mortality events in poultry farming businesses. The cause of death was cardiorespiratory failure caused by overheating. Characteristic macroscopic findings were scalp cyanosis, skeletal muscle anaemia with a cooked-meat-like appearance, petechiae and hyperaemia of internal organs. Microscopic examination revealed venostasis, with dilated blood vessels overfilled with erythrocytes. The diagnostic findings document hyperaemia, cyanosis, a cooked meat-like appearance, noticeable venostasis of internal organs and intravascular haemolysis. These findings resulted from pathological conditions that developed gradually in a warm environment and led to death. The pathophysiology and changes that develop as a consequence of high temperatures are discussed. This article could be useful for veterinary pathologists diagnosing deaths caused by prolonged exposure to extraneous environmental high temperatures.