Crash Course on Calcium
When you feed a homemade diet, adding the right amount of calcium is vital.
Cook's Corner column by Mary Straus, published in Dog World Magazine February 2010.
No homemade diet is complete without calcium, yet many recipes omit this important ingredient. Although a lack of calcium won’t cause immediate problems, a deficiency can lead to bone deformities, pain and even fractures over time.
Calcium-phosphorus balance is something that's often discussed in both human and canine nutrition. There should always be more calcium than phosphorus. Recommended rations for dogs range from 1-to-1 to 2-to-1 calcium to phosphorus. If calcium and phosphorus are not properly balanced in the diet, the body pulls calcium from the dog's bones to make up for that deficiency, leaving them weakened.
When to add calcium – and when not to
You must add this essential mineral to all homemade cooked diets and to raw diets that do not include raw meaty bones. If you feed a combination of fresh and commercial foods, and more than about one quarter of your dog’s diet is fresh foods, it’s best to add calcium to balance out the phosphorus in the added foods. The more fresh foods you add, the more important it becomes to provide calcium.
As important as it is to add calcium to homemade diets, it is equally important not to add calcium to complete-and-balanced commercial diets, especially for large-breed puppies and pregnant females. Although excess calcium is not dangerous for adult dogs (they simply excrete what they don’t need), calcium binds many minerals, so adding too much decreases the nutritional value of what you feed.
Puppies younger than six months have less ability to control their absorption of calcium, so an excess amount can lead to skeletal problems, such as hypertrophic osteodystrophy (HOD, a bone disease that causes severe pain and lameness, often in multiple limbs), osteochondrosis (OCD, which affects cartilage, causing severe joint pain) and hip dysplasia, particularly in large-breed puppies.
Bitches that are given extra calcium during pregnancy can develop a life-threatening condition called eclampsia when they begin nursing puppies. This condition is caused by the body’s inability to adjust quickly to the sudden need for more calcium after receiving too much before. It is fine to give extra calcium after the puppies are born, just don’t increase calcium before whelping.
Not enough calcium
People often think feeding high-calcium foods such as yogurt will supply enough calcium to balance a homemade diet. But the amount of calcium in these foods is only enough to balance the phosphorus they contain; it's not enough to balance the phosphorus in the rest of the diet or meet a dog’s calcium needs.
The same is true of multivitamin and mineral supplements. Although these supplements often contain calcium, they are designed for dogs that are already getting adequate calcium in their diets.
One food that provides more than enough calcium is raw meaty bones that dogs can fully consume, such as chicken necks and backs, whole or ground. If your dog's diet includes at least 20 percent raw meaty bones, there's no need to add calcium to the diet.
Sources of calcium
You can use any form of plain calcium, such as calcium carbonate or calcium citrate. Calcium from seaweed is a good choice because it provides other beneficial minerals, primarily magnesium, but also small amounts of zinc, potassium, iodine and selenium. The same is true of bone meal. Calcium from oyster shells, dolomite and bone meal can be contaminated with lead, so look for brands that state they have been tested and found to be safe. Bone meal; calcium carbonate; calcium citrate; and calcium fro seaweed, oyster shells and dolomite are marketed for people, and can be found in health food stores, drug stores and even many grocery stores. You can also use products made for dogs, such as Animal Essential Natural Seaweed Calcium (formerly Calcium from the Sea).
Ground eggshell is one source of calcium that's easy to obtain. Rinse the eggshells and dry them in an oven set to a low temperature or on the counter overnight, then grind them in a clean coffee grinder. To ensure the calcium can be fully absorbed, grind eggshells to powder rather than just crushing them into pieces.
One-half teaspoon ground eggshell provides approximately 1,000 milligrams calcium. Ground eggshells will last indefinitely as long as they are kept dry. Some people prefer to refrigerate them, but it's not necessary.
Certain dog food mixes, such as Preference from The Honest Kitchen and Homemade Dinner Mixes from See Spot Live Longer, are designed to have fresh foods added to them. These types of mixes usually contain calcium, so it’s not necessary to add any more as long as the product states that it meets Association of American Feed Control Officials (AAFCO) guidelines when fed as directed. If unsure, contact the manufacturer and ask.
How much calcium
A good rule of thumb is to add approximately 800 to 1,000 milligrams of calcium, or ½ teaspoon ground eggshell, per pound of fresh food. If you feed a combination diet of fresh and commercial foods, add enough calcium to match only the amount of fresh food; do not factor in the commercial food.
Because growing puppies need more phosphorus than adult dogs, bone meal is the best source of calcium for them. Bone meal contains phosphorus in addition to calcium, so if you use bone meal, increase the amount to 1,000 to 1,200 milligrams of calcium per pound of food. Each brand of bone meal will provide a different amount of calcium per teaspoon. Check the produce label before using.
For example, if you give your dog 8 ounces (½ pound) of fresh food, add 400 to 500 mg of plain calcium, or ¼ teaspoon ground eggshell, or 500 to 600 milligrams of calcium from bone meal. If you use bone meal that provides 1,200 milligrams calcium per teaspoon, add ½ teaspoon of bone meal to your dog’s diet.
Don’t forget to split the calcium between meals. If you feed 8 ounces of food daily, split between two meals, add 200 to 250 milligrams plain calcium, or 1/8 teaspoon ground eggshell, or 250 to 300 milligrams of calcium from bone meal, to each meal.
Check your recipes
During the 2007 pet food recall, I read a lot of recipes that did not mention adding calcium. Many books on homemade diets also leave out this important information (or discuss it in a separate section), and don’t specify how much calcium to add.
It isn't harmful to feed occasional meals that don’t include added calcium. Adult dogs can get by without added calcium for a few weeks or even months, but eventually a deficiency of this mineral will cause serious consequences. If you choose to feed a homemade diet, be sure to add an appropriate amount of calcium to keep your dog healthy.
If you have any questions or comments, you can contact me, but I have less time to answer questions than I used to, and it may be several days to a week before I can respond. My name is Mary Straus and you can email me at either or