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Balancing the Calcium/Phosphorous Ratio in a Raw Diet for Dogs

From the desk of Mogens Eliasen - first published: October 21, 2006 (update of a previous article from 2003)

Mogens Eliasen - the author of this article
on 'the Calcium/Phosphorous balance'

Most dog owners that feed their dogs a raw, natural diet will know about the Calcium/Phosphorous balance, which is vital for the dog's health. Many dog owners even resort to supplementation of particularly Calcium, "just to be sure".

Unfortunately for the uneducated, the assumption "when something is good, then more of it must be better" is absolutely not true when applied to chemistry in a live body…..

The problem with chemical analyses…

The "nutritional requirements" you can get from official tables, and the values that are published for "the optimal balance" of Calcium and Phosphorous are dangerous guidelines for feeding…

The reason is that a chemical analysis of the Calcium contents and the Phosphorous contents of the food will not tell you the entire truth about the balance between those two "nutrients". What you can measure with standard chemical analysis and what truly matters for the body's metabolism are not the same… What is analyzed chemically is the total concentration of the chemical elements, regardless what kind of compounds they occur in. What matters for the body is the occurrence of all the various chemical compounds that contain the element in question, in the right balance, and in the right chemical environment. Certainly not the same as the total concentration!

For start, Calcium is a metal - and it is extremely poisonous…. The Calcium you find in chemical compounds is not the metal itself, but the ions, which consist of metal atoms, each stripped of two electrons, so they become positively charged. This attracts them to negatively charged ions, to which they bind more or less heavily, subject to a lot of chemistry…

What is relevant to the body are the available ions. The Calcium ions as well as the negatively charged ions that come along with them. And that availability is seriously subject to some very complicated chemistry that cannot be deducted from knowing the total concentration of Calcium…

Next, for Phosphorous, this is even more complicated. Elementary Phosphorous is definitely not healthy to ingest! Phosphorous will naturally occur in many types of negatively charged ions, like phosphates of all kinds, where Phosphorous is directly attached to Oxygen. But Phosphorous will also bind to Carbon in proteins - in a number of ways that is too large to be counted by humans… Each of all these many variants of Phosphorous compound has its own chemical balances in the body, and those balances are generally not linked to each other at all!

In other words: talking about "total Phosphorous" or "total Calcium" (which is what you generally get from a cheap standard chemical analysis) is completely meaningless, if not outright deceiving. All you can tell from such an analysis is that that you may or may not have enough of all the variants the body needs of the element in question, except when the measure is too low to allow for that. In such case, you can conclude that "something is missing", but you have no qualified clue as to what is missing.

If you use artificial ingredients, you can easily have the chemical analysis show that the concentrations are "right" - but in reality, they might not represent accessible nutrients in useable quantities. Example: Limestone contains significant amounts of Calcium, and will show up in a chemical analysis with its high Calcium content. But limestone is next to impossible to digest, so almost all of its Calcium will be discharged through the feces, exactly as it was ingested….

However, when your Calcium and Phosphorous sources are raw natural food, chances are that you will be supplying both of those two elements in a mixed balance of chemical compounds that are digestible and accessible for the metabolism.

Problems with over-supply from artificial sources…

The statement "Although it might not have much value, supplementing cannot do any harm" is unfortunately false when it comes mineral nutrients.

Calcium provides the easiest example to understand for illustration.

Calcium in bones is heavily bound to the bone structure that also consists of the phosphate ions. This means that, even when the dog gets a large amount of bone, the total concentration of Calcium ions in the stomach remains very low, totally independent of the amount of bone. But, as those available Calcium ions are absorbed through the walls of the gastrointestinal system, more Calcium ions are produced from the bones. In other words: Nature will take care that the Calcium is made available through a steady supply of a very small constant concentration of Calcium ions! This supply will be the same, no matter how many bones the dog eats - it will not depend on the total amount of Calcium at all, except if supplies are too sparse!

But there are other chemical compounds that also matter for the dog's body. Other trace nutrients, such as Cobalt, Copper, Manganese, Titanium, Vanadium, and many more metal ions, as supplied through their natural chemical compounds, are of equal importance, even though they are required in much smaller amounts.

The bad news is that many of them have some chemistry that is somewhat similar to that of Calcium. This means that they, in some way, compete with Calcium in order to get access to the body through their specifically designed absorption gateways. These gateways are quite selective, but not 100% selective. Some other metal can sometimes block the access for the designated metal ions by simply crowding the entrance!

This is exactly what happens when the dog's stomach suddenly gets an excessively high concentration of Calcium ions. The absorption of other metal ions will decrease then, possibly far below the body's needs. This means that an oversupply of Calcium can lead directly to an undersupply of other, equally important metal ions! You see, what counts is not what nutrients are in the food, but which of them get absorbed into the body…

So, what matters here are not the total amounts of Calcium in the food, because the Calcium ions that are heavily bound to other chemicals do not contribute to this problem. But those that are supplied from artificial sources might very do exactly that…. This is particularly true when those supplements are in a form that is "readily absorbable by the body"!!! And, if they are less absorbable, they are valueless.

The only situation where artificial supplementation might have positive value and no negative side-effects would be when they would provide a concentration of free Calcium ions in the stomach that would be exactly equal to what the dog would obtain from raw bones. If you can find a manufacturer of a Calcium supplement who dares to write this on the label of the supplement, I would like to know!

That was Calcium. As I said, the chemistry of Phosphorous is far more complicated - but the main principles are exactly the same, except for the fact that scientists know even less about all the details, simply because there are too many to take into account, and the appropriate research is not financially feasible.

Using raw bones as the source

Being left now with only natural sources of Calcium of Phosphorous, our attention should turn to bone as our source of those two nutrients. Bones contain the right balance a dog needs. If we feed enough of it, the balance problem is solved.

But what about those other imbalances in the diet? Don't we need to compensate for those? For instance, if we have too little Calcium, don't we then need to add more Phosphorous than what we have in bones?

The answer is that it does not matter - if you feed enough bones.

Here is why: Let's say that the right ratio between some relevant forms of Calcium and Phosphorous in 1:1 - 50% of each. Let's further say that the dog needs 100 milligrams (=0.1 grams) of each per day, and that bones contain 10% of each. This leads us to conclude that we should feed a total of 1,000 milligrams (=1 gram) of bone per day to cover the needs, assuming that all the Calcium and all the Phosphorous in bones is digestible.

However, in the food we feed, we might have a deficiency of Calcium. Let's say that the food contains only half the Calcium it should (50 milligrams instead of 100 milligrams), but is okay as far as Phosphorous goes. We are thus out of balance - our 1:1 ratio is only 0.5:1 - which is critical.

But, let's say that we now feed 10 grams of raw bone. This will give us a total supplement of 1,000 milligrams of Calcium and 1,000 milligrams of Phosphorous. Add to this what we feed through the other sources of food. This brings the Calcium intake up to a total of 1,050 milligrams, and the Phosphorous to a total of 1,100 milligrams. Our overall balance is now no longer 0.5:1, but (1050/1100):1 = 0.95:1. We are only 5% "off". But 5% is within the natural variation anyway, so it won't matter… (Also: most standard chemical analyses do not give a more precise result anyway: +/-5% is pretty accurate for such an analysis…)

If you feed 100 grams of bone instead, you will see the ratio go to 0.995:1 - less than 0.5% off the mark…

The good news in this is that dogs thrive very well on getting a lot of raw bones. (Mind you, in nature, a wolf will hardly leave anything of a kill, except for the hooves and the scull.)

And better yet: you don't need to know anything about the actual deficiencies of Calcium or Phosphorous in the food you feed. You don't even need to know which of the two is missing or insufficient, or in which chemical form they occur. All you need to do is to give your dog plenty of raw bones that will make the imbalances in the food totally insignificant.

How much is "plenty"? A good guide would be to use a natural prey animal as standard - about 7-10% of its total weight will be bone, so anything in excess of 10% of the total diet would be "plenty". You should not exceed 25% - because you do need to leave room for other nutrients also…

Dogs love bones - so this will make you a popular pack leader!


Mogens Eliasen


Mogens Eliasen holds a mag. scient. degree (comparable to a US Ph. D.) in Chemistry from Århus University, Denmark, has a extensive education also as military officer and in business management. He has been working with dogs, dog owners, dog trainers, and veterinarians since 1970. A large part of his dog work has been in the area of education and education planning, and as consultant for dog owners and dog training associations. He is a strong advocate of treating the dog with respect for its nature as domesticated wolf, and has published several books and videos on topics related to dogs, dog training, dog behavior, and responsible care of dogs. He publishes a newsletter "The Peeing Post" containing lots of tips and advice on all matters pertaining to dogs.

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Titles available from K9joy®:

Anders Hallgren:
"The ABC's of Dog Language" (140 page book - 1996)
Understand what your dog is telling you - and communicate with it on its own terms. A must have for all dog lovers. Easy to read. Easy to use as reference.

Mogens Eliasen:
"The Dog's Social Behavior" (2.5 hr. video - 1998, updated on DVD 2006, with support materials on a CD)
How the dog's behavior is linked to its instincts and needs. What you can change and what is "for life". How you use this information to dramatically improve your relationship with your dog.

Mogens Eliasen:
"BrainWork for Smart Dogs" (380 page e-book - 2003)
How you get a happy and well-behaved dog, stimulating its brain with 15 minutes of fun per day. Dogs need to work and use their instinct in order to be in mental balance. Everyone can do it with these instructions. More than 40 exercises to choose from!

Mogens Eliasen:
"Don't Pull on the Leash!" (40 page e-book - 2005)
The 5 simple steps in this complete training manual will effectively stop any dog from pulling on the leash, with no pain or abuse and no special equipment - and make the start of a much better relationship with the dog.

Mogens Eliasen:
"Is Your Dog's Drinking Water Safe?" (30 page e-book - 2005, updated 2006)
A layman's overview of how and why drinking water gets contaminated - and what you can do about it.

Mogens Eliasen:
"Feeding Your Dog - the Natural Way" (1 hr. video - 1998)
The fastest introduction to get you started on feeding your dog a natural diet. It explains the dog's physiology in simple terms, so you also understand why you should do this.

Mogens Eliasen:
"Canine Choice - by Nature" (80 page e-book - 1999, updated 2005)
The simple "how-to" about feeding a natural diet for optimal health.

Mogens Eliasen:
"Raw Food for Dogs - the Ultimate Reference for Dog Owners"
(340 page e-book - revised/expanded 2006)
Everything you need for making your own informed decisions about what to feed your dog, and why and how. Includes numerous examples of feeding plans plus two chapters on how to work with your vet, also if he/she does not approve of your feeding...

Mogens Eliasen:
"The Wolf's Natural Diet - a Feeding Guide for Your Dog?"
(125 page e-book - 2004 updated/revised 2006)
What we know and don't know about the wolf and its natural feeding, and about the dog and its domestication, and what we can and cannot conclude from wolf to dog... this is the big "why?" behind any responsible approach to feeding your dog.

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