How to Balance Calcium In Your Dog’s Diet

How to Balance Calcium In Your Dog’s Diet

How much calcium do you think is in a 75 lb dog’s body?

One pound! That makes it a pretty important mineral. And it’s very easy to get the calcium balance wrong in your dog’s diet. If you’re making your own dog food you’ll want to know how to avoid this mistake and get the right amount of calcium in your dog’s diet.  

It’s complicated. So let’s break it down so you can balance the calcium, and other minerals too. 

The Importance of Calcium For Dogs

About 99% of your dog’s calcium is in his bones. Phosphorus and calcium are essential for your dog’s skeletal health so he needs to have enough in his diet. Calcium is also found in the blood and lymphatic system where it supports hormone, cardiovascular and immune functions as well as cell structure and enzyme activity, 

Calcium allows cells to respond to hormones and neurotransmitters. Neurotransmitters at the ends of nerves release calcium ions into the muscles and cause the muscle to contract. In fact, rigor mortis is due to calcium … the muscle cell membranes become more permeable after death and allow calcium in. Normally, ATP (adenosine triphosphate) works with calcium to relax the muscles. But ATP isn’t produced after death, so the excess calcium creates the muscle contractions in rigor mortis.

Rigor mortis shows the importance of keeping calcium levels within a small range. Too much or too little and your dog could develop seizures, lose muscle control … and ultimately die.

Low Calcium Levels In Dogs (Hypocalcemia)

Without enough calcium in your dog’s food, the parathyroid hormone pulls calcium out of his bones to maintain circulating levels of calcium. If this happens for weeks or months, you’ll see skeletal issues, such as rickets and bone loss. This will show in your dog as limping, stiffness, muscle twitching, and bone pain.

Puppies are at greater risk from insufficient calcium than adult dogs. Puppies need more calcium to grow bone. If there’s not enough calcium in the puppy’s diet, it can cause osteochondritis dissecans (OCD), hypertrophic osteodystrophy (HOD), hip and elbow dysplasia and panosteitis. This also happens if the ratio of calcium to phosphorus is unbalanced..

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Nutritional Secondary Hyperparathyroidism

Dogs get a condition called nutritional secondary hyperparathyroidism. It’s caused by having insufficient calcium in the diet. This happens when there are large amounts of phosphorus and too little vitamin D. Then too much parathyroid hormone gets produced and too much calcium gets pulled from the bones. Bone weakens (this is osteopenia) and you’ll see neurological signs related to low blood calcium. This can show up as muscle twitching or seizures. Nutritional secondary hyperparathyroidism can be resolved with  correct levels of calcium and phosphorus.

Too Much Calcium (Hypercalcemia)

Too much calcium in the blood causes hypercalcemia. It happens when the hormone calcitonin removes calcium from the blood into the bones. Most adult dogs have no problem dealing with large amounts of calcium in the diet. They should have little trouble maintaining blood calcium levels, other than possibly a bit of constipation. But puppies can’t balance calcium like adult dogs. When there’s too much calcium it can cause joint and skeletal issues. This is especially true if calcium isn’t balanced with phosphorus, other minerals and vitamin D.

If you’re feeding a balanced diet for all life stages, then there should be enough calcium in the food … and it should also be balanced with phosphorus. But to be sure, always check that the food says “Complete and Balanced” on the label. Then you’ll know the foods meets the minimum nutritional requirements set by the  Association of Feed Control Officials (AAFCO). You shouldn’t add calcium supplements to complete and balanced foods, especially for puppies, they’re already balanced. But if you’re home cooking or raw feeding your dog, you’ll need to add calcium to his meals. Let’s look at some calcium sources and how much to feed your dog.

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How Much Calcium Do Dogs and Puppies Need?

Calcium and phosphorus must both be correct. They’re regulated in the body by the parathyroid hormone and vitamin D. Calcium needs to combine with phosphorus before being stored in bones. Too little calcium or too little phosphorus can cause skeletal issues in dogs. Calcium and phosphorus together give bones their structure and strength.

When your dog’s diet has too much phosphorus, calcium is pulled from the bones to balance phosphorus blood levels. Too much phosphorus in the diet weakens bones and causes calcium deposits in soft tissue. When adding calcium to home-made diets, you need to pay attention to calcium and phosphorus. These are three things to consider ...

  1. Amount of calcium in the food
  2. Amount of phosphorus in the food
  3. Calcium to phosphorus ratio

AAFCO Calcium Requirements

AAFCO sets minimum and maximum requirements for calcium and phosphorus in dog foods. So we can use AAFCO requirements to balance calcium and phosphorus in homemade diets. Puppies need larger amounts of calcium, so there are different requirements for adult dogs and puppies:

Min Calcium

Max Calcium

Min Phosphorus

Max Phosphorus

Min Ca:P

Max Ca:P

1.25 g / 1,000 kcal

6.25 g / 1,000kcal

1 g / 1,000kcal

4 g / 1,000kcal

1:1

2:1

AAFCO/NRC Calcium and Phosphorus For Adult Dogs

Min Calcium

Max Calcium

Min Phosphorus

Max Phosphorus

Min Ca:P

Max Ca:P

3 g / 1,000 kcal

6.25 g / 1,000kcal

2.5 g / 1,000kcal

4 g / 1,000kcal

1:1

2:1

AAFCO/NRC Calcium and Phosphorus For Growth & Reproduction

Meat is high in phosphorus and low in calcium. But bones are rich in calcium and phosphorus with a Ca:Ph ratio of about 2:1. This means an all-meat diet is deficient in calcium so you need to add calcium in some form.

Raw feeders add bone to their meals to balance the Ca:P ratio. The dilemma is that many raw fed dogs can’t eat bone. If you’ve got a senior dog, a dog with poor teeth, a small dog or a puppy, they can find it difficult to chew bone. That puts them at risk for calcium deficiency. Bones can also splinter or break teeth. For these dogs, you’ll need to add a different source of calcium to their food.

Bones must be fed raw so cooked diets need added calcium. Here are some calcium sources you can add to raw and cooked meals.

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Where To Find Calcium Sources

Not all calcium sources are the same and they’re not all suitable for puppies. Here are the most common calcium supplements and foods you can add:

  1. Eggshells
  2. Coral calcium
  3. Seaweed calcium
  4. Coral calcium
  5. Bone meal
  6. Bone

Each source has different amounts of minerals. Here’s the dry matter breakdown:

Calcium Source

Calcium

Phosphorus

Ca:P

Magnesium

Egg Shells

33.7%

0%

0

Coral Calcium

34%

0.1%

425:1

2.4%

Seaweed Calcium

34.2%

0.8%

41.7:1

3.42%

Bone Meal

19.3%

9.3%

2.1:1

2.46%

Bone

15.6%

2.9%

2:1

0.11%

Nutrients (Dry Matter)

Real bone is the gold standard for adding calcium to your dog’s diet. It has a  2:1 ratio of Ca:P so it provides a good amount of phosphorus as well as magnesium and vitamin D. By comparison, seaweed and coral calcium contain very little phosphorus. Eggshells are extremely different from bone with no perceptible amount of phosphorus or magnesium. So eggshells are an unnatural alternative to bone.

Let’s look at these calcium sources to see how much you need to add to your dog’s food.

How To Add Calcium To Homemade Foods

Kibble and most commercial pet foods get formulated on a dry matter basis (meaning the amount of a nutrient that’s left after the moisture is removed from the food). This works for kibble because most kibble is the same … but not for raw and home cooked diets. Because of their fat calories, these need to be formulated on a caloric basis, not a dry matter basis like kibble. In other words, the amount of calcium in 1,000 calories of food. This is because fat contains twice as many calories as protein or carbohydrates. 

Here’s a breakdown of each calcium source and how it balances diets with various fat levels. We don’t advocate feeding a diet with more than 20% fat … because fat is low in vitamins and minerals, so your dog could miss some nutrients. So you should only feed higher fat diets with veterinary guidance. This is especially important for puppies and pregnant dogs. They wouldn’t be able to get enough nutrition from their food without eating more calories than needed. Keep in mind that much of your dog’s meal is water weight, so a food that’s 20% fat will only contain about 10% protein. So it’s best to feed 10% fat and definitely no more than 15% fat.

Egg Shells As A Source Of Calcium

When home made diets use egg shells as a source of calcium, be aware that they’re deficient in other minerals. You’d feed about 1 tsp or 5 grams per pound of food. Here’s how calcium balances minerals in adult dog foods. As shown, egg shells must only be used with very lean meats. If you feed more than 10% fat (including any oils you add to the food), your dog won’t get enough phosphorus.

Adult Dogs

1 teaspoon Eggshell Powder (5 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

2.35

1.19

2:1

15% Fat (85% Lean)

1.91

0.89

2.2:1

20% Fat (80% Lean)

1.61

0.69

2.4:1

AAFCO Adult Minimum Requirements

1.25

1.00

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal

Puppies & Pregnant/Nursing Dogs

Puppies need nearly double the amount of calcium as adult dogs. When you double the amount of egg shells, there’s enough calcium in the diet. But egg shells only contain calcium, so the food  still won’t meet minimum AAFCO requirements for phosphorus. So eggshell powder isn’t sufficient for growth and reproduction.

2 teaspoon Eggshell Powder (10 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

4.62

1.19

2:1

AAFCO Puppy Minimum Requirements

3.00

2.50

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal. Minerals in red do not meet requirements.

Coral Calcium

Coral calcium is also extremely high in calcium but relatively low in phosphorus. So it’s another poor choice for adult dogs eating a moderate to high fat diet. If you’re adding coral calcium, you need to make sure your dog’s meals are very lean or he’ll have a mineral imbalance and phosphorus deficiency. You’ll need to feed 3/4 tsp per pound of food that’s no more than 10% fat. There will be a phosphorus deficiency in food that contains more than 10% fat.

Adult Dogs

3/4 teaspoon Coral Calcium Powder (3.6 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

1.79

1.17

1.5:1

15% Fat (85% Lean)

1.46

0.88

1.7:1

20% Fat (80% Lean)

1.24

0.7

1.8:1

AAFCO Adult Minimum Requirements

1.25

1.00

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal. Minerals in red do not meet requirements.

Puppies & Pregnant/Nursing Dogs

Puppies would need more coral calcium to meet AAFCO minimum requirements. But even when you double the amount of coral calcium it doesn’t increase phosphorus levels enough to balance the minerals. So don’t feed coral calcium to puppies or pregnant or nursing dams.

1 1/2 teaspoon Coral Calcium Powder (7.2 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

3.44

1.16

2.9:1

AAFCO Growth & Reproduction Minimum Requirements

3.00

2.50

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal. Minerals in red do not meet requirements.

Seaweed Calcium

Seaweed calcium is also high in calcium and low in phosphorus. So it’s  challenging to use with anything but very lean meats. Like coral calcium, just adding more seaweed calcium won’t balance the minerals because there’s still too little phosphorus. Feed 1 tsp per pound of food that’s no more than 10% fat.

Adult Dogs

1 teaspoon Seaweed Calcium Powder (3 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

1.50

1.22

1.2:1

15% Fat (85% Lean)

1.22

0.91

1.3:1

20% Fat (80% Lean)

1.03

0.71

1.5:1

AAFCO Adult Minimum Requirements

1.25

1.00

1:1

AAFCO Puppy Minimum Requirements

3.00

2.50

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal. Minerals in red do not meet requirements.

Puppies & Pregnant/Nursing Dogs

You’d need to add 3 tsp of seaweed calcium to meet the minimum calcium requirements for growth and reproduction. But this doesn’t provide enough phosphorus … and the Ca:P ratio doesn’t meet AAFCO requirements. Seaweed calcium isn’t recommended for growth and reproduction.

3 teaspoon Seaweed Calcium Powder (9 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

4.34

1.29

3.4:1

AAFCO Puppy Minimum Requirements

3.00

2.50

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal. Minerals in red do not meet requirements.

Bone Meal

Bone meal is bone that’s dried with or without heat. Minerals are resistant to heat, so it’s usually safe to heat and powder bones. But if you can find it, it’s better to use higher quality sources of bone meal that hasn’t been heat treated.

When you use bone meal over other sources of calcium, there’s much less risk of mineral imbalance. Just like real bones, it will usually give you the proper ratio of calcium and phosphorus. Feed adult dogs about 2 tsp per pound of food.

Adult Dogs

2 teaspoons Bone Meal Powder (8 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean)

2.12

2.15

1:1

15% Fat (85% Lean)

1.72

1.67

1:1

20% Fat (80% Lean)

1.46

1.34

1.1:1

AAFCO Adult Minimum Requirements

1.25

1.00

1:1

AAFCO Puppy Minimum Requirements

3.00

2.50

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal.

Puppies & Pregnant/Nursing Dogs

Fresh bones are best for puppies and pregnant dogs. But bone meal is the next best source of calcium. It contains both calcium and phosphorus in the right ratio. So larger amounts will deliver enough calcium without creating the imbalance between calcium and phosphorus you’d get with the other calcium sources. Feed about 4 tsp per pound of food for meals that are 10% fat. If feeding 15% fat, then there won’t be quite enough phosphorus, so increase it to 5 tsp. If there is 20% fat or more (more than 20% fat isn’t recommended for puppies), then increase bone meal to 6 tsp.

4 teaspoons Bone Meal Powder (16 g) Added To 1 Pound Food:

Calcium

Phosphorus

Ca:P

10% Fat (90% Lean) – Add 16 g Bone Meal or 4 tsp

4.09

3.09

1.3:1

15% Fat (85% Lean) – Add 20 g Bone Meal or 5 tsp

4.12

2.81

1.5:1

20% Fat (80% Lean) – Add 24 g Bone Meal or 6 tsp

4.13

2.62

1.6:1

AAFCO Puppy Minimum Requirements

3.00

2.50

1:1

AAFCO Maximum Requirements

6.25

4.00

2:1

Amount per 1,000 kcal.

Beware Of Toxins And Heavy Metals

You need to be aware of potentially harmful substances in any calcium source you choose. Let’s look at the potential problems with each:

Egg Shells

There’s a chemical coating on most store bought eggs that’s toxic to your dog. Egg shells aren’t recommended as a source of calcium so this is easy to avoid. But if you choose to use them, buy them from a local farmer who washed the eggs with water only.

Coral and Seaweed Calcium

These types of calcium come from the ocean and are often high in heavy metals like mercury, PCBs and dioxins. It’s important that your source of sea calcium has tested low in these toxic substances.

Bone Meal

Bone meal can be a source of lead and glyphosate. The best bone meal to use should come from young animals. It should be tested low in lead, pesticides, herbicides and other heavy metals.

Here’s The Best Source Of Calcium For Dogs

Never doubt Mother Nature. Real bones have the right balance of calcium and phosphorus and balance all meals, even for puppies. Bone meal is a good option when it’s high quality and tested for heavy metals. Better Bones from Four Leaf Rover is what we recommend. These bones are sourced from pastured young cattle from Australia, and air dried. Then each batch is third party tested for metal and pesticide contamination. Alternatively, calcium hydroxyapatite is another option. It should be third party tested for safety. 

Egg shells, seaweed and coral calcium are all rich in calcium but very low in phosphorus. You shouldn’t feed them to puppies or pregnant/nursing dams. If using these as a calcium supplement for adult dogs, they will only balance foods that are 10% fat or less (remember, oils will raise the fat content if added to your dog’s meals). When your food contains more fat, you need to feed too much calcium or too much phosphorus so you need to stick to lean foods.

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Dicalcium phosphate, calcium citrate, calcium carbonate or calcium proteinate are other sources of calcium. These are the chemical versions added to dog foods … but you’re feeding raw or home cooking to give your dog a higher quality diet. These are what you’ll find in kibble and commercial foods, so they’re best avoided. And we don’t advise using chemical minerals made in a lab … food-based nutrition is always the best option over synthetic nutrition.


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