Overview of Perirenal Hemorrhage Syndrome of Turkeys
(Hypertensive angiopathy, Sudden death syndrome of turkeys)
Perirenal hemorrhage syndrome (PHS) is a noninfectious cardiovascular disorder usually affecting rapidly growing male turkeys 8–15 wk old. It is characterized by sudden death, perirenal hemorrhage, and hypertrophic cardiomyopathy. Mortality is usually 0.5%–2% but can be higher; there is no morbidity. Healthy, rapidly growing flocks are more likely to be affected.
The pathogenesis is unknown, but PHS is apparently unrelated to pulmonary function or hypertension. Inadequate or inappropriate cardiac response to exercise, resulting in systemic hypotension and vasodilation, ventricular arrhythmia, and sudden death, appears most likely. Acute congestive heart failure secondary to cardiac hypertrophy is also a potential cause. Renal hemorrhage may occur due to severe passive congestion; acute blood loss is likely not the primary cause of death because the extent of perirenal hemorrhage is variable and often mild.
Gross lesions include food in crop and stomach, enlarged dark red to purple spleen, variable retroperitoneal hemorrhage around one or both kidneys, generalized congestion, and pulmonary edema occasionally accompanied by hemorrhage. Body condition is usually good to excellent. Cardiac hypertrophy involving the left ventricle and intraventricular septum may also be seen. Microscopic changes are consistent with gross findings and include pulmonary congestion and edema with renal perivenous hemorrhage. Intimal vacuolation and medial hyperplasia of arteries and arterioles have been described in multiple organs, particularly the kidney, spleen, and lung of turkeys with PHS; however, similar lesions can be seen to a lesser extent in tissue of normal turkeys.
Diagnosis is based on history, typical gross lesions, and absence of infectious agents. PHS has several characteristics in common with aortic rupture (see Dissecting Aneurysm in Turkeys) and sudden death syndrome of broilers (see Sudden Death Syndrome of Broiler Chickens). Extensive PHS lesions can resemble aortic rupture, and these two disorders can occur simultaneously in the same flock.
There is no specific treatment. Factors that decrease growth rate and activity also tend to decrease PHS. Reserpine (0.5 ppm feed) decreases PHS, but aspirin (0.005%) or increased calcium has no effect. Reserpine is not listed in the Feed Additive Compendium as approved for use in feed for turkeys. Increased room temperature and step up/step down lighting programs have also reduced PHS. Activities that increase cardiovascular stress (eg, moving birds, tilling litter, noise) should be minimized, especially between 7 and 15 wk of age. Lower ambient temperatures (55°F [13°C]), intermittent lighting, and leaving toes unclipped increase mortality from PHS. PHS may occur in commercial flocks of healthy male turkeys, regardless of management practices used to prevent its occurrence.