Primary hypoparathyroidism in two horses

Two Thoroughbred horses were presented with various clinical signs which in cluded sweating, agitation, muscle twitching and synchronous diaphragmatic flutter. These signs were associated with profound hypocalcaemia. A diagnos is of primary hypoparathyroidism was made on the basis of low serum ionised calcium concentration, hyperphosphataemia and markedly reduced serum immun oreactive parathyroid hormone concentrations in the presence of normal rena l function. Treatment with a combination of intravenous calcium and subsequ ently oral calcium, magnesium and a vitamin D analogue (dihydrotachysterol) for up to 65 days resulted in complete remission of clinical signs. Horse 1 was euthanased 12 months after the initial recognition of signs. Results of necropsy were unremarkable apart from an absence of detectable parathyro id tissue. Horse 2 returned to athletic activities while receiving only mai ntenance doses of oral calcium carbonate.