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Calcium to Phosphorus Ratio

When it comes to the feeding raw,  calcium to phosphorus balance is essential to the development and maintenance of a strong and healthy skeletal structure. There are a few guidelines you need to follow, but the most important one is balancing the minerals calcium and phosphorus in your dog’s diet.


Meat, especially organ meat such as brain and liver are very high in phosphorus. Some fish like sardines and salmon are high in phosphorus as well. The main function of phosphorus is in forming bones and teeth.

It plays an important role in the body’s use of fat as well as in synthesizing protein for the growth, maintenance and repair of cells and tissues.

Phosphorus is also crucial for the production of ATP, a molecule the body uses to store energy. Phosphorus works with B vitamins. It also helps with muscle contraction, kidney function, heartbeat regularity and nerve conduction.


Bone is high in calcium and in phosporus. According to Dr Ian Billinghurst (author of Give Your Dog a Bone and other well known books on canine nutrition), calcium’s role goes far beyond bone mineralization. Calcium is essential for neuromuscular, cardiovascular, immune and endocrine function. It’s vital for blood clotting.  Calcium forms the skeletal structure or cytoskeleton within each cell, and every cell in the body depends on calcium to support enzyme functions, bodily signalling and to maintain cell membrane stability.

Dogs need a balance between the amount of phosphorus and calcium they get in their daily diets.

The ratio of calcium to phosphorus should be about 1:1, but preferably with slightly more calcium than phosphorus.

This is especially important in young, growing dogs, who need an adequate supply of raw meaty bones in their diet to provide a good balance of calcium and phosphorus. Feeding all-meat diets (which are are high in phosphorus and low in calcium) to young pups can cause skeletal problems.

According to the Merck Veterinary Manual, insufficient calcium or excess phosphorus can lower calcium absorption and result in irritability, hyperesthesia (oversensitivity to sensory stimuli), and loss of muscle tone. Calcium deficiency can also cause skeletal demineralization, particularly of the pelvis and vertebrae. Excess calcium can also interfere with normal healthy bone mineralization and growth, especially in young (under 1 year old) large and giant breed dogs. Large breeds fed excess calcium are more likely to suffer from developmental bone disease such as osteochondrosis (abnormal bone growth).

Balancing The Calcium:Phosphorus Ratio

It might seem daunting to calculate the calcium:phosphorus ratio in a home prepared raw diet for your dog  … but it’s really not that complicated. Bones are a safe source of dietary calcium and if dogs eat enough of them, the diet will be balanced without a lot of difficult calculations.

Dr Billinghurst explains:

Approximate biological balance is achieved so long as meat alone is not the principal dietary component. That job must be left to the raw meaty bones (RMBs). When a young and growing dog eats RMBs, if the bone to meat ratio of those RMBs is around 1:1, then the balance of calcium to phosphorus is appropriate for bone mineralization and formation.

Dr Billinghurst also says that adult dogs need less calcium and, as long as you’re feeding a raw diet with raw meaty bones, the adult dog’s body will absorb the calcium it needs and leave what it doesn’t in the intestines.

Overall, balancing calcium and phosphorus isn’t all that difficult, as long as dogs receive plenty of bone. In general, any bone content over 10% is plenty.

When sourcing bones for your dog’s diet, it’s a good idea to know the approximate amount of bone in commonly sourced foods. Here is a quick guide Feeding RMB's 

Source Material via Dogs Naturally

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