Cypermethrin and α-cypermethrin are highly active pyrethroid insecticides. The present study aimed to diagnose the pathological changes of cypermethrin on different organs of pigeons after orally long term exposure (four months) to cypermethrin at low dose (0.25 mg/day), intermediate dose (0.75 mg/day), at and high dose (1 mg/day). The heart showed clear vacuolation of myocardial muscles cells at low and intermediate doses, besides at high dose vacuolation and congestion were observed. In liver, many pathological changes were observed; at low dose congestion of central veins, at intermediate dose, proliferation of bile duct and congested sinusoid in periportal region with diffuse vacuolation of hepatocytes, where at high dose minimal septal fibrosis, foci of mononuclear cells vacuolation of hepatocytes and congestion were noticed. Emphysema, congestion, and foamy alveolar macrophages were found in lung at low, intermediate, and high dose, respectively. A clear vacuolation and degeneration of cortical tubules were found in kidney at low dose, while, at intermediate dose a vacuolated cortical tubules were noticed, but a regeneration cortical tubular basophilia and vacuolation were found at high dose. The spleen showed suppression in lymphoid tissue at low and intermediate dose, while, at high dose a clear aggregation of lymphocytes enclosed by fibrous capsule were noticed. The brain showed no changes, but the sciatic nerve and the spinal cord showed few degenerate vacuolated nerve fibres in low dose and brought to several degenerate /vacuolated nerve fibres at intermediate and high doses. In conclusion, it must be attention that cypermethrin make a high risk factor not only on fishes, cattle, plant but also on birds which exposed to cypermethrin by food or water.
Key words: Cypermethrin, Pigeon, Foamy alveolar, Vacuolation, Organs.