Hi Boerboel Daddy –
You do not want to put mom onto a low calcium food. Growth of the fetuses during gestation and providing the pups with milk during lactation requires massive amounts of calcium. During the final 35 days of gestation, requirements for calcium and phosphorus increase by around 60%. During lactation, depending on litter size, bitches may require between 2-5 times as much calcium as is required for adult maintenance. When you wean the pups you can place them on an appropriate large breed puppy formula. So I’d say it would be fine to stick with Acana for now.
