Information from NRC and Canine and Feline Nutrition and Small Animal Clinical Nutrition


Primarily found in the skeleton. Remaining distributed extracellular fluids

Provides structural integrity of the skeleton and maintains proper blood calcium levels through ongoing resorption and deposition. Calcium is always coming and going from the bone for growth and maintenance and as the body’s need for plasma calcium fluctuate. Circulating plasma is strictly controlled through homeostatic mechanisms and is independent of food intake of calcium. Circulating calcium is crucial for nerve impulse transmission, muscle contraction, blood coagulation, activation of certain enzyme systems, maintenance of normal cell-membrane permeability and transport, and cardiac function

Circulating plasma calcium is controlled by homeostatic mechanisms. A constant level is crucial. Mechanisms specifically refer to PTH, calcitonin, and active Vitamin D- calcitriol.

Signs of Deficiency
Nutritional Secondary Parathyroidism
Spontaneous Fractures

Signs of Excess
Impaired Skeletal Development

Can interfere with absorption of other minerals: Phosphorus, Zinc

Bone, Supplementation, and dairy (though not always the best choice)

Veggies are not a reliable source of calcium because of absorption issues.

Supplements, such as calcium carbonate or ground bone, can be mixed in with meat- rather than other nutrients which require feeding them fresh.

Recommended ratio cal:p is 1:1 – 2:1


Primarily found in the skeleton- following behind calcium, while the remainder is distributed in soft tissues.

Also lends structural support to the skeleton and is also released into the bloodstream similar to calcium. Involved in almost all of the body’s metabolic processes. A constituent of cellular DNA and RNA, some B-vitamin coenzymes, and the cell membranes phospholipids. This is crucial for regulating the transport of solutes into and out of the cells (so many many many processes in the body in general). Is also needed for the phosphorylation reaction that are a part of many oxidative pathways for the metabolism of the energy-containing nutrients.

Phosphorus is needed for cell respiration.

Signs of Deficiency
Depraved appetite, pica, decreased growth, decreased fertility, dull coat, spontaneous fractures, rickets.

Signs of Excess
Hypercalcemia, bone resorption, soft tissue calcification

Can interfere with calcium and magnesium absorption.

Meat, poultry, fish, bone

Phosphorus from plant sources can be absorbed at a fraction (1/3) of animal sourced phosphorus.


Most found in the body exists in the form of phosphates and carbonates in the bone. The rest is found within cells and some in extracellular fluid.

Provides structure to skeleton. It also functions in many metabolic reactions. Magnesium-ATP complex is often the form of ATP that is used as a substrate in many of these processes. As a cation in the extracellular fluid, this mineral is essential for the metabolism of both carbs and protein. Protein synthesis requires the presence of ionized magnesium. Balanced in the extracellular fluids with calcium, sodium and potassium, this mineral allows muscle contraction and proper transmission of nerve impulses. Involved in over 300 enzymes. Can be lost in the cooking process due to leaching into cooking liquid.

Signs of Deficiency
Soft tissue calcification
Enlargement of large bone metaphysis
Neuromuscular Irritability

Signs of Excess

Meat, supplementation, some digestible carbohydrates


Found in all body cells, mainly hemoglobin and myoglobin. Stored Primarily in the liver, spleen, and marrow. Also functions as a cofactor for several other enzymes.

Present in all body cells, iron present in Hemoglobin aids in transport of oxygen from the lungs to the tissues while myoglobin binds oxygen for the immediate use by muscle cells

Iron is a cofactor for several other enzymes and a component of the cytochrome enzymes.

Signs of Deficiency
Increased clotting time, hemorrhage. This would be very rare and would normally occure because of chronic blood loss

Signs of Excess
There are few studies of toxic intake of iron for both dogs and cats and when symptoms manifest for toxicity, it was due to experiments with fasting dogs and/or supplementation. There is no SUL for iron in dogs or cats because the experiments are not applicable to dogs eating standard diets. There is not enough data for cats. Iron should never be supplemented carelessly and is easy to meet iron needs without a supplement.

High dietary intake of iron can affect hepatic copper stores. (In studies where the ratio of iron to copper exceeded 20:1).  Very high levels of iron should also be avoided because of interference with minerals such as zinc and copper. The body has limited ability to excrete iron and therefore homeostasis is maintained by adjusting iron absorption.

Overall, iron absorption is affected by
1. Iron status of the body
2. Availability of dietary iron (as affected by other ingredients and nutrients)
3. Amount of heme and nonheme iron.

Sources & Nutrient Interactions

Organ meats (liver, kidney), egg yolk and fish are high in iron.

Heme iron from animal sources is much better absorbed than non-heme sources (plants). During formulation, one should take care to recognize the source where iron is coming from.

An acidic intestinal environment generally improves iron absorption.

When the body has low stores of iron and increased metabolic needs will increase absorption efficiency.

Phytate, phsphate, and exceess oxalates can negatively affect absorption. Excess zinc and calcium can also negatively affect absorption.



Mainly found in the blood bound to plasma protein ceruloplasmin. Found in liver and excess excreted in bile.

Copper is needed for normal absorption and transport of dietary iron. Oxidation of iron is required for binding to transferrin. Copper is needed for the conversion of amino acid tyrosine to the pigment melanin, for the synthesis of collagen and elastin, and for the production of ATP. Copper is a vital constituent of many enzymes. Copper also plays a role in elimination of free radicals, bone development, and pigment development. Copper is also needed for the formation of myelin sheath.

Signs of Deficiency
Hypochromatic microcytic anemia
Impaired skeletal growth young animals
Depigmentation of colored hair coat.

Signs of Excess
Inherited disorder of copper metabolism causes liver disease in some breeds of dogs:

cocker spaniels, dalmatians, german shepherds, keeshonds, kerry blue terriers, labs, old english sheepdogs, poodles, samoyeds

Organ meats- with the exception of pork liver. Beef, sheep, and turkey are highly available sources.


Widely distributed across all tissues.

Zinc is a component of many metalloenzymes. It is a cofactor in the synthesis of DNA and RNA and protein. Essential for cellular immunity and reproductive functions. Zinc is important for vitamin A metabolism.

Signs of Deficiency

Dermatoses, hair depigmentation, growth retardation, reproductive failure. Clinical signs show: anorexia, testicular atrophy, immune dysfunction, conjunctivitis, skin lesions

Signs of Excess
Even though zinc is relatively non-toxic, excess zinc can interfere with other minerals like iron and copper. Zinc toxicosis in dogs or cats have only been due to dietary indiscretion. (The dog ate pennies for example). 

Sources & Interactions

Excess calcium, iron, copper, and fiber and the presence of phytate can affect zinc absorption.

Liver, beef, dark poultry meat, eggs


Main cation in intracellular fluid. ⅓ of cells potassium is bound to protein. The rest is in ionized form.

Ionized potassium with cells provide osmotic force that maintains proper fluid volume.

Also responsible for numerous enzymatic reactions.

The small amount the extracellular fluid aids in transmissions of nerve impulses and muscle contraction. Therefore, is important for the normal functioning of the heart muscle.

It helps regulate the acid-base balance of the body.

Converts glucose to glycogen in the liver and needed for normal growth.

Meats, poultry, fish


Ionized sodium is the major cation found in extracellular fluid. Provides osmotic force that maintains aqueous environment in the extracellular fluid. Functions to maintain normal irritability of nerve cells and contractility of muscle fibers.

Sodium controls the electrolyte balance between intra & extracellular fluid compartments. Sodium chloride is a chief source of sodium.

Dogs and cats seem to be physiologically capable of adapting to wide ranges of sodium intake. Sodium should be watched in pets with certain health conditions.

Located outside the cells in the surrounding fluid. It is also inside the cells and in bones. Fluid and acid base balance of the body.


Chloride ions make up for about ⅔ of total anions present in extracellular fluid. Regulate osmotic pressure, water balance, and acid-base balance. Important for the production of gastric enzymes.

Dietary needs parallel sodium intake.


Manganese functions as a component in cell enzymes. Manganese can be found in the mitochondria of cells. Manganese helps regulate nutrient metabolism. Manganese is also especially important for growing animals in regards to bone development and reproduction.

Manganese is found in plant sources- such as quinoa. Dietary needs differ from dogs to cats.

In other species, manganese deficiency has caused decreased growth, impaired reproduction, and disturbances in lipid metabolism.

Manganese is needed for cartilage and is critical for joint health.


Iodine is needed for the synthesis of hormones thyroxine and triiodothyronine by the thyroid gland.

Too much or too little can have serious effects. Meat has varying levels of iodine that do not show up in food databases and therefore many programs- such as PDD, Cronometer, Nutrient Data.

You should do additional searches depending on what you use in your recipes.

Naturally occurring iodine deficiency does not occur commonly in dogs or cats, though principal sign of deficiency is goiter. Failure to grow, skin lesions, and CNS dysfunction can occur in growing animals fed a deficient diet.

Fish, eggs, supplements


Even though many nutrients including minerals do not have safe upper limits, all minerals are toxic at high doses.

 When supplementing minerals, take great care to know how much you are supplementing and how much is needed in the diet. 

Take care to investigate the form of the mineral. 

You should not, for example, feed 2 weeks worth of a mineral need via supplement in one day. (Ex feed a high dose of zinc supplement in one day)