Electrical stunning of lambs: The effect of stunning parameters and drugs affecting blood flow and behaviour on petechial haemorrhage incidence

Head-to-back electrical stunning of lambs results in speckle bruising, a kind of petechial haemorrhage in muscle fascia, especially when the lamb is tightly restrained. Other factors still appear to modify speckle and some of these are investigated here. There was a significant increase in leg speckle with long stunning duration or high stunning current, but there was little or no increase for the loin. When phenylephrine, a vasoconstrictor, was administered before stunning, there was a reduced speckle compared with the administration of isoproterenol, a vasodilator. The greatest speckle resulted from high currents and isoproterenol administration. These results are consistent with the view that increased blood at speckle sites, i.e. a blush, during the spasm that takes place during stunning, increases speckle. In lambs tranquillized with valium or excited with adrenaline there was no significant difference in speckle for the legs. There was a significant increase of speckle in the loins of valiumtreated lambs. Although increased peripheral blood flow may increase speckle, the effects of stress such as release of adrenaline may reduce this effect.