CT venography and pathological characterization of crus haemorrhage in Pekin ducks

The crus haemorrhage is one of the main causes of carcass defects in Pekin duck processing houses. However, its pathologic features are currently unclear. In order to examine the injury to the hind limb veins and illustrate the pathologic characteristics of crus haemorrhage in Pekin ducks, a total of 68 Pekin ducks with crus haemorrhage (test group) and 10 unaffected ducks (control group) were collected in this study. Five ducks randomly selected from each group were examined by computed tomographic venography with 2.0 mm thickness, 120 kVp, and 90 mA. Pathological changes were observed macroscopically, and under a microscope and electron microscope. The computed tomographic venography results showed no differences in the main hind limb veins between Pekin ducks with crus haemorrhage and the control. Macroscopic results demonstrated that the haemorrhage only occurred in crural muscles, most frequently in musculus gastrocnemius and musculus tibialis cranialis. In severe cases, muscular rupture and multiple intermuscular blood clots could be observed. Histological analysis showed rupture of myofibers and massive red blood cells between muscle bundles. Besides, infiltration of connective tissues and inflammatory lesions could be seen. However, no differences were observed in other organs between these two groups. The main ultrastructural characteristics were myofibrillar rupture and split, accompanied by mitochondrial membrane disintegration and vacuolization. All these results indicate that the haemorrhage in crus is a focal myopathy with the characteristics of bleeding, rupture, and inflammatory lesions. Research highlights CTV was a feasible method to evaluate the hind limb veins in Pekin ducks. The focal myopathy presented here only affected crural muscles. The focal myopathy was characterized by bleeding, rupture and inflammatory lesions.