Mycotic abortion

Abstract

History and Clinical Signs : Abortions ordinarily are sporadic and the total incidence within a herd seldom reaches 10% of the pregnant cows. January through March is generally the period of highest incidence in the northern hemisphere. There are no common prodromal or postabortion signs in the cow. Gross Lesions : Severe placentitis is a constant lesion with necrosis, thickening and cupping of the cotyledons, leathery thickening of the intercotyledonary tissue and adventitious placentation occurring commonly. In about 25% of the cases ringworm-like lesions of the fetal skin occur. The fetal tissues usually do not have signs of preexpulsion autolysis. Frequently the lungs are partially expanded. The carcass may be somewhat dehydrated and emaciated. Microscopic Lesions : Necrotizing inflammation of the chorionic villi often with vasculitis and thrombosis is a constant lesion. Varying amounts of mycelia and necrotic intervillus tissue are associated with this lesion. Occasionally suppurative bronchopneumonia with associated mycelia occurs. Mycotic skin lesions of epidermitis and folliculitis associated with mycelia occur in approximately 25% of mycotic abortion cases. Cultural Procedures : The etiologic fungus usually can be isolated from the fetal abomasal contents, the placenta, occasionally from the fetal lungs, and when skin lesions are present, from the skin. In some cases, mycotic lesions are present but the organism cannot be isolated. The ubiquity of fungi must be kept in mind when interpreting the results of culture procedures. Serologic Procedures : No serologic procedures are commonly used. Special Procedures : The use of special stains, such as Gridley's, Gomori's methenamine silver nitrate and PAS, aid greatly in determining the presence of mycelia in tissues. Microscopic examination for mycelia of KOH digested placenta or skin scrapings aids in providing an early tentative diagnosis. Preferred Diagnostic Procedures : 1. 1. Demonstrate gross or microscopic lesions of placentitis with associated mycelia. 2. 2. Demonstrate skin lesions with associated mycelia. 3. 3. Demonstrate bronchopneumonia with associated mycelia. 4. 4. Culture of fungi from fetal abomasal content, skin lesions or lungs.