Chronic ingestion of high concentrations of cholecalciferol in cats

To determine whether ingestion of 63 times the recommended amount of vitamin D3 (cholecalciferol) results in renal calcification or damage in cats.

20 four-month-old kittens, 17 queens, and 20 kittens born to these queens.

4-month-old kittens and queens were given a purified diet with 846 microg of cholecalciferol/kg of diet (high vitamin D3 diet) or 118 microg of cholecalciferol/kg of diet (control diet) for 18 months. Kittens born to queens were weaned onto the same diet given to dams.

There were no apparent adverse effects of the high vitamin D3 diet. Plasma cholecalciferol and 25-hydroxycholecalciferol (25-OHD3) concentrations of queens and 4-month-old kittens given the high vitamin D3 diet significantly increased with time. At 6 months, plasma cholecalciferol concentrations in these kittens and queens were 140.0+/-7.3 nmol/L and 423.6+/-26.6 nmol/L, respectively (10 times initial values). Corresponding 25-OHD3 concentration in queens was 587.5+/-59.4 nmol/L (2.5-fold increase over initial values). At 3 months of age, kittens born to queens given the high vitamin D3 diet had an increase in serum BUN and calcium concentrations and a decrease in RBC and serum total protein, albumin, and hemoglobin concentrations. By 18 months, these kittens had an increase in plasma cholecalciferol (276.0+/-22.2 nmol/L) and 25-OHD3 (1,071.9+/-115.3 nmol/L) concentrations. However, all indices of renal function and the appearance of renal tissue on histologic evaluation were normal.

These results indicate that cats are resistant to cholecalciferol toxicosis when the diet is otherwise complete and balanced.