Phosphorus and Calcuim in Your Dog’s Diet

August 22, 2010

By Spencer Roach
Research and Development
Steve’s Real Food Inc.
Eugene, OR 97401

Raw diets, when prepared properly, are certainly the healthiest ways to feed dogs. But too often many people get confused about the proper ways to add calcium and phosphorus and change a great diet into a poor diet. Dogs need the proper amounts of calcium and phosphorus in order to grow well and remain healthy. This article will outline how much calcium and phosphorus dogs need, why, and will list the calcium and phosphorus sources of common ingredients used by many raw feeders.

Calcium and phosphorus are both essential minerals in canine diets. Calcium is a critical component of bone and cartilage, and it also plays a minor role in hormone transmission. Phosphorus is also a major component of bone. Calcium and phosphorus are found in bone as calcium hyoxyapatite, with a molecular formula of Ca10(PO4)6(OH)2. While the calcium/phosphorus ratio in hydroxyapatite is 1.7:1, energy-carrying molecules such as ATP (adenosine tri-phosphate) and others increase non-skeletal demand for phosphorus. As such, the optimal dietary calcium/phosphorus ratio is between 1.2:1 and 1.3:1. The chart below lists calcium/phosphorus minima and maxima for various life stages on a dry matter basis1.

Growth Adult Maintenance Maximum
Calcium 1.0% 0.6% 2.5%
Phosphorus 0.8% 0.5% 1.6%

Calcium/phosphorus metabolism is mediated by 1,25(OH)2-vitamin D in the small intestine, and by parathyroid hormone in the bloodstream. There is a complex feedback loop that balances intestinal absorption, bone resorption, and renal excretion of both minerals. Too much calcium can result in increased bone density, which has been implicated as a factor in hip dysplasia in young and old dogs alike. Too little calcium can cause bone demineralization (and consequently an increased risk of skeletal fracture) and stunted growth. Phosphorus excess can lead to renal damage, while phosphorous deficiency is rarely (if ever) seen in carnivores.

Most of the calcium and phosphorus in Steve’s Real Food chicken and turkey varieties comes from raw, ground up chicken backs or turkey necks. We also use a variety of calcium and phosphorus supplements in order to reach optimum levels of nutrition. Many raw diet advocates overestimate the levels of phosphorous in meat. Meat and pure calcium supplements alone do not provide adequate levels of phosphorus. We found through extensive nutrient analysis that we had to add phosphorus in conjunction with calcium. We use several pure calcium sources and calcium/ phosphorus sources to fine-tune our food’s nutrition. Below are the calcium and phosphorus contents of some common raw meaty bones and other mineral sources. Also included are moisture, protein, and fat, so the mathematically inclined can estimate the dry matter calcium/phosphorus content as well as the energy density. Carbohydrate content is negligible for all ingredients.

Calcium (%) Phosphorus (%) Moisture (%) Protein (%) Fat (%)
Beef, whole 0.07 0.2 65.5 19.6 12.2
Chicken Brest 0.01 0.17 69.5 20.9 9.3
Chicken Backs 0.48 0.4 60.7 12.6 24.4
Chicken Wings 0.87 0.78 64.8 17.2 12
Turkey Necks 0.69 0.73 62.5 12.4 19.9
Beef Bonemeal 30.6 11.3
Egg Shell Powder 38.1
Dicalcium 29.4 23

1) Association of American Feed Control Officials (AAFCO), Official Publication, 2001.

5 Responses to Phosphorus and Calcuim in Your Dog’s Diet

  • This is important data for those feeding raw to dogs with chronic renal failure. Thank you so much for listing the calcium and phosphorus for commonly fed raw components, even if only percentages.

  • Hi, Thank you so much for posting this info! We have a dog with some major bone/joint issues, including a collapsed femur head with hip dislocation. We are trying to figure out how to balance his calcium and phosphorus, since one vet prescribed Ca Tablets and now we are finding out that they might cause some issues as well! Do you know of any vegetarian sources of phosphorus that we could add to his diet? Thank you!

  • We feed double ground rabbit or turkey mixed with beef blend which is ground organ meat. Some honest kitchen HALE. One of our dogs eats NW Naturals chic/salmon. Salmon oil, green juju, Synovi g4, mushroom powder and answers goat milk. We have 3 frenchies and an English.

  • My dog recently had her bloodwork done and came back very low in phosphorous. She is on a raw diet with supplements to be sure she is getting what she needs. My vet is not concerned but I am. It seems she’s not absorbing the phosphorous she’s digesting. Can you help me? Please?

  • Hello!

    In our diets we do use a natural source of calcium and phosphorus so that it can be used in the dogs body. On our website under the diet you are interested in, it will show how much phosphorus is in our food so you are able to see if it fits your needs.

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