SECONDARY HYPERPARATHYROIDISM IN TWO PONIES

The purpose of this case series was to describe the historical, clinical, radiographic details, outcome and histhopathological findings of 2 cases of NSH in pony. CASE 1 A 3 years old, male pony was referred in 2003 for severe dyspnoea and deformity of the bones of the skull. At clinical examination, the pony had general fatigue, severe dyspnea and inspiratory breath sounds. X‐ray examination showed signs of severe thinning of the cranial bones with loss of definition of the plot medullary and cortical thinning cancellous bone. The results of parathyroid hormone by radioimmunological showed an increase in the values of PTH .Treatment has been provided using tiludronate (TILDREN 1mg/kg‐ ®‐Ceva Vetem SpA, Milan). The patient's clinical condition showed significant improvements, the clinical symptoms (inability to maintain the station, lameness and respiratory sounds) had resolved. The pony was dismissed. CASE 2 In October of 2012 was referred a 5 years old Shetland male pony, and the owners permanent recumbency since 3 days.General clinical examination showed persistent recumbency , slight enlargement of facial bones and pain at flexion of hindlimbs. Based on the clinical symptoms, X‐rays and laboratory tests, the diagnosis was of NSH related to fibrous osteodystrophy. The clinical condition of the horse showed no improvement and the subject was not able to take quadrupedal station. The owner disagrees with Tiludronate therapy and pony was euthanized, and some bone samples were harvested in order to deepen the diagnostic picture. Microradioghaphs of frontal serial sections show modifications of bone tissue arrangement and mineralization.. The trabecular network appears rarefied owing to a thinning of the trabeculae or their total erosion. Both spongy and compact bone frequently exhibit large osteocytic lacunae. On the other hand new bone, less mineralized, is exthensively present. The deposition fronts show a wide osteoid with voluminous osteoblast, but sometimes exhibit numerous preosteoblasts with a fibroblasts morphology. In many area, fibrous connective tissue covers the trabecular surfaces and replaces part of the marrow reticular stroma. The appearance of micro X‐ray, never described in the horse, and the histological evidence and confirm the diagnosis of fibrous osteodystrophy. Bisphosphonate therapy is a therapeutic option, and it is valid for the possible remission of clinical symptoms but not certain deformities of the disease. The association of such therapy with a balanced diet can be part of the treatment protocol in the course of NSH of dietary origin. David et all., the bisposphonate Tiludronate is a potent inhibitor of the osteoclast vacuola hatpase, Journal of Bone and Mineral Research, 11, 1498‐1507, 1996 Estepa, J. C., Aguilera‐Tejero, E., Mayer‐Valor, R., Almeden, Y., Felsenfeld, A.J. & Rodriguez, M. Measured of parathyroid hormone in horses. Equine Veterinary Journal 30, 476‐481, 1998