One year of continuous heparinization in the dog using a totally implantable infusion pump

Continuous anticoagulation was carried out in 25 dogs for longer than 6 mth, and of these, 7 were heparinized for more than 1 yr, as shown by persistent elevations of all 3 coagulation parameters. Eight dogs of the control group which received pump infused bacteriostatic water for 6 to 12 mth showed no elevations in coagulation parameters. Serum alkaline phosphatase values did not change. Mean serum calcium and bone mineral density values determined after 6 and 12 mth of heparin infusion were significantly lower than preoperative control values but did not differ significantly from dogs receiving water during the same time periods. The decreases in mean bone mineral density for dogs receiving heparin - 11 to 15% after 6 mth; 22% after 12 mth - are less than the 27% decrease seen in moderate clinical osteoporosis but suggest that some bone demineralization may have occurred. That an 11% decrease in mean bone mineral density occurred for 3 dogs which received bacteriostatic water for 1 yr suggests that factors in addition to heparin may be involved.