Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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Myopathies in Turkeys D. K. Onderka Animal Health Laboratories Branch Alberta Agriculture, Food and Rural Development
Five separate cases of disease outbreaks in turkeys are reported. The flocks involved were either turkey broilers, heavy turkeys or breeder birds. The age ranged for 6 ½ to 20 weeks. In all flocks, the clinical history indicated increased mortality for the preceding 24 to 48 hours, listlessness in general and birds in sternal or lateral recumbency, unable and unwilling to rise. In some cases, this was associated with a recent change in feed. In other cases, it was associated with movement of the birds from one barn to another. Gross examination showed either no lesions, slight pallor of the adductor muscle; in some birds, distinct pale streaking of the adductor muscle and pale foci on the epicardium. In contrast, a 15 ½ week old broiler breeder flock with similar clinical signs had distinct and severe white streaking of the pectoral musculature. Microscopic examination showed degenerative changes in the striated muscles in all birds submitted. This was in most cases restricted to the thigh muscles (except for the broiler breeders) and included, in one case, also the cardiac muscle. The lesions ranged from loss of striations with hyalinization and fragmentation to necrosis, proliferation of Sarcolemmal nuclei and fibroblast invasion, hemorrhage, and in some cases, early fibrous tissue replacement repair. Besides some macrophage invasion inflammation was not a feature. Occasionally, a fine blue granular stippling suggested mineralization. This also occurred in the heart lesion. In the pectoral muscles of the broiler breeders, necrosis with fragmentation was the main feature. In feed related incidences, Salinomycin was supplied to some of the turkeys at levels of 15 to 45 ppm, respectively. In a 19 week old breeder flock, broiler feed containing 68 ppm Monensin was supplied erroneously. The flock that was moved a week earlier and the broiler breeder flock had no feed related problems. In these cases, movement of the birds caused exertional myopathy (turkeys); while in the broiler breeder flock it resulted primarily in deep muscle myopathy. Microscopic examination of muscle lesions clearly revealed the cause for the leg weakness, but failed to aid in the differentiation of the various causes. Careful history might point towards the various possibilities, which should include ionophore toxicity, Vitamin E deficiency, extertional myopathy, and early stages of "deep muscle myopathy". |
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