Doc Roy's Healthy Bones is a calcium supplement tablet sold at
Pet Health Supplies | Pet Supplies | Revival Animal Health. I buy a lot of my pet supplies from them.
Your vet might sell Pet-cal. I highly recommend getting something asap. Also from Revival I recommend having some Oral Cal Plus. It is very important to have some on hand just in case your girl gets eclampsia.
Also to help prevent eclampsia it is important that your momma eats about 4 meals a day. I feed mine a dry puppy food that I soak in warm water and I add some canned food with it. Some mommas are very picky about eating after having pups. Sometimes the only way my spoiled girls will eat is if I sit there and hand feed them. Try to make sure your girl eats her last meal right before bedtime. Most cases of eclampsia occur in the morning after the pups have sucked on the momma all night. I usually feed mine around 9 at night. Sometimes I get up in the middle of the night to feed the momma again if she is nursing a lot of puppies.