Bastianello S S, Fourie N, Prozesky L, Nel P W, Kellermann T S
Section of Pathology, Onderstepoort Veterinary Institute.
Onderstepoort J Vet Res. 1995 Mar;62(1):5-18.
This report contains an account of the gross and histopathological lesions of 20 cattle and four sheep in 15 field outbreaks of poultry litter toxicity, one steer fed ad lib. and six sheep dosed with toxic poultry litter, and ten sheep fed experimental rations containing c 2,5 ppm and 5 ppm maduramicin. The principle macroscopic lesions in most cattle that died in field outbreaks were indicative of congestive heart failure. The lesions in sheep were similar, but generally milder. Cardiac dilatation was observed in both sheep and cattle. Microscopically, the cardiac lesions were more pronounced in cattle and comprised varying degrees of atrophy, hypertrophy, degeneration, necrosis of myocardial fibres, and interstitial fibrosis. Skeletal muscle lesions were usually more severe in sheep, particularly in the muscles of the hindquarters which appeared pale, oedematous and mottled. One of the sheep in the poultry litter dosing trial developed signs of congestive heart failure and the hearts of two others were dilated. Extensive hypertrophy and atrophy of myocardial fibres were evident in the steer fed ad lib. with this material. As in field cases, the myocardial lesions of the sheep were less severe than those of the steer. Mild cardiac dilatation was present in four of the seven sheep in the maduramicin feeding trial. Diffuse hypertrophy of myocardial nuclei was present in all seven cases, myocardial fibre atrophy in six, multifocal fibrosis and necrosis in six and two cases, respectively, and focal endocardial thickening in two. The skeletal muscles revealed granular degeneration and foci of necrosis and regeneration. The cardiac and skeletal lesions in the field outbreaks, poultry litter feeding trials and maduramicin feeding trials, were highly comparable. This suggests that this form of poultry litter intoxication is a chronic form of ionophore toxicity the pathology of which is characterized by a dilated cardiomyopathy with congestive heart failure and mild (cattle) to severe (sheep) skeletal muscle lesions.
本报告记录了15起家禽垫料中毒的田间疫情中20头牛和4只羊的大体及组织病理学病变情况，1头自由采食有毒家禽垫料的阉牛、6只经口给予有毒家禽垫料的羊，以及10只饲喂含2.5 ppm和5 ppm马杜霉素实验日粮的羊的病变情况。在田间疫情中死亡的大多数牛的主要大体病变表明存在充血性心力衰竭。羊的病变与之相似，但通常较轻。在羊和牛中均观察到心脏扩张。显微镜下，牛的心脏病变更为明显，包括不同程度的心肌纤维萎缩、肥大、变性、坏死以及间质纤维化。羊的骨骼肌病变通常更严重，尤其是后肢肌肉，表现为苍白、水肿和斑驳状。在家禽垫料经口给药试验中，有1只羊出现充血性心力衰竭症状，另外2只羊的心脏扩张。自由采食这种垫料的阉牛心肌纤维出现广泛的肥大和萎缩。与田间病例一样，羊的心肌病变比阉牛的轻。在马杜霉素饲喂试验的7只羊中，有4只出现轻度心脏扩张。所有7例均存在心肌细胞核弥漫性肥大，6例出现心肌纤维萎缩，6例和2例分别出现多灶性纤维化和坏死，2例出现局灶性心内膜增厚。骨骼肌显示颗粒变性以及坏死和再生灶。田间疫情、家禽垫料饲喂试验和马杜霉素饲喂试验中的心脏和骨骼肌病变具有高度可比性。这表明这种形式的家禽垫料中毒是一种慢性离子载体中毒形式，其病理学特征为扩张型心肌病伴充血性心力衰竭以及轻度（牛）至重度（羊）的骨骼肌病变。
