Calcinosis involving multiple paws in a cat with chronic renal failure and in a cat with hyperthyroidism

Calcinosis of multiple paws is described in two cats. A metastatic pathogenesis was supported by the laboratory findings of hyperphosphataemia and a calcium x phosphorus solubility product > 7 g/L. Hyperparathyroidism could not be confirmed because a valid feline parathyroid hormone assay was not available at the time. One cat was diagnosed with chronic renal failure and presented initially with an irregular nodular calcification on the chin. Dietary and medical management was unsuccessful and ultimately the animal was euthanased. Hyperthyroidism was diagnosed in another cat by laboratory findings and scintigraphic imaging. In addition, the cat had a hyperphosphataemia in the absence of azotaemia. Intravenous administration of radioactive iodine as (131)I was accompanied by reduction and normalization in serum total thyroxine and phosphorus concentrations and resulted in resolution of calcification in the paws.