Practical Matters: Do not institute calcium supplementation during canine pregnancy
Parathyroid hormone is secreted in response to decreased serum calcium concentrations. The hormone increases calcium concentrations by promoting osteoclastic activity and increasing calcium uptake from the gastrointestinal tract. Oral calcium supplementation causes persistent serum calcium elevation with subsequent downregulation of parathyroid hormone. When the bitch whelps and begins lactating, it is difficult for oral supplementation alone to provide enough calcium since it is poorly absorbed through the gastrointestinal tract. Because the parathyroid hormone has been downregulated in dogs receiving oral calcium, bone calcium stores cannot be accessed and hypocalcemia results.
Instead of calcium supplementation, pregnant bitches should be fed a well-balanced puppy or performance food during the latter half of gestation. Calcium supplementation during lactation will not cause iatrogenic hypocalcemia, so supplementation may be instituted at whelping.Margaret V. Root Kustritz, DVM, PhD, DACT
Department of Veterinary Clinical Sciences
College of Veterinary Medicine
University of Minnesota
St. Paul, MN 55108