Zur Kalzinose in Österreich IX. Kalzinose beim Pferd?

Enzootic calcinosis in ruminants: A review

Enzootic calcinosis (EC), is a chronic disease, caused by toxic plants, which has mainly affected ruminants for more than 100 years. It is characterized by a soft tissue calcification, hypercalcemia, hyperphosphatemia, hypoparathiroidism, hypercalcitoninism, osteonecrosis, and osteopetrosis. The toxic compound reported in some of these plants are 1,25(OH)₂D₃ glycosides. Characterization of calcinogenic principles were performed with Solanum glaucophyllum, Trisetum flavescens, Cestrum diurnum, and Stenotaphrum secundatum. Other plant species involved in EC are: Nierembergia rivularis, Nierembergia veitchii, Solanum torvum, and Solanum stuckertii. Clinical and pathological findings are well characterized. We present different aspects of the pathogenic mechanism of EC, including genetic modulation, expression of bone proteins, cellular de-differentiation of arterial smooth muscle cells, phenotypic changes, production of a calcifiable matrix, and modulation of the calcium and phosphorus balance. The use of comparative pathology can bring significant advances in the understanding of the pathogenic mechanism. In this review we present a broad approach to the different aspects of intoxication: history of EC on different continents; plant species, distribution and morphology; toxic principle; pathogenesis; epidemiology; clinical signs; diagnosis; and control and prophylaxis.

[Yellow oat grass intoxication in horses: Pitfalls by producing hay from extensive landscapes? A case report]

Vitamin-D intoxication by yellow oat grass is often reported under the syndrome of enzootic calcinosis in ruminants in the upper regions of the Alps. The intake of Trisetum flavescens in ruminants and horses induces calcification of soft tissue, including vessels, tendons and ligaments, lung, heart and kidneys. Clinical symptoms, including a reluctance to move, inappetence, body-weight loss and impaired organ function, are frequently observed. To date, there are only a very few case reports about yellow-oat-grass intoxication in horses. The present case report describes Vitamin-D intoxication by yellow oat grass in a riding stable in Thuringia, Germany. The horses, which were fed hay with a 50% contamination of Trisetum flavescens, displayed symptoms, including inappetence, body-weight loss, colic, polydipsia and polyuria. The hay, contaminated with Trisetum flavescens, was harvested from an extensively cultivated landscape according to the European Fauna-Flora-Habitat (FFH)-directive. The present case report demonstrates the pitfalls in producing hay from extensively used landscapes and indicates some peculiarities of Vitamin-D metabolism in horses.

Calcinosis--calcinogenic plants

The calcinogenic plants are among the most noxious plants to animals in the world. The pathological and biochemical effects of calcinogenic plants in cattle, sheep, goats, pigs, horses, buffalo and laboratory animals have been determined. The chemical nature of the toxic agents and the precise mechanism by with the calcinogenic plants induces calcinosis have been defined. Most of the active principle present as steroidal glycoside is hydrolyzed in intestine, rumen and other tissues or by the bacterial flora releasing the steroidal fragment, in most cases 1,25(OH)(2)D(3). The excess of vitamin D stimulates CaBP synthesis and calcium and phosphate absorption, producing hypercalcemia and/or hyperphosphatemia. The excessively absorbed mineral cannot be physiologically accommodated, and the deposition in soft tissues results in calcinosis. The different means of treatment of calcinosis and control of calcinogenic plants are discussed with regards to their effectiveness. A number of potential uses of calcinogenic plants have been suggested but none has been exploited on a large scale. The understanding of the mechanisms involved with calcinosis contributed enormously to the compression of vitamin D mechanism. Research methods were developed and improved but a lot is to be done in this fascinating subject.

Intimal asteroid bodies in horses: light and electron microscopic observations

The morphology of asteroid bodies in equine arteries is demonstrated by light microscopy as well as by scanning and transmission electron microscopy combined with chemical analysis. Asteroid bodies first occur in horses at four weeks of age in all investigated tissues except the esophagus and always are located in the subendothelial space. The number, shape, ultrastructure and chemical composition of asteroid bodies differ markedly--depending on the age of the horse. Asteroid bodies are round and smooth in foals, but are shaped irregularly and have several projections and marked stratified calcification in adult horses. Asteroid bodies probably originate from smooth muscle cells. No direct etiological connection between asteroid bodies and migrating Strongylus vulgaris could be verified.