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==What is Phosphorus?==

==What is Phosphorus?==

After [[Calcium - Nutrition|calcium]], phosphorus is the '''second most prevalent mineral in mammals''', including dogs and cats. Like calcium, it is found in the highest proportion in bone (about 86%) but is also found in other tissues such as muscle (about 8.6%). Like calcium it does not exist in its free state but in the form of phosphates.

After [[Calcium - Nutrition|calcium]], phosphorus is the '''second most prevalent mineral in mammals''', including dogs and cats. Like calcium, it is found in the highest proportion in [[Bones - Anatomy & Physiology|bone]] (about 86%) but is also found in other tissues such as muscle (about 8.6%). Like calcium it does not exist in its free state but in the form of phosphates.

==Why is it Important?==

==Why is it Important?==

'''Phosphorus has many key functions, principally as a component of compounds essential to normal metabolism'''. These include: phospholipids and phosphoproteins that are important in membrane formation; the nucleic acids DNA and RNA; other nucleotides such as ATP that are vital components of energy metabolism; enzyme cofactors. Phosphorus also has a role in regulating acid-base balance.

'''Phosphorus has many key functions, principally as a component of compounds essential to normal metabolism'''. These include: phospholipids and phosphoproteins that are important in membrane formation; the nucleic acids [[DNA]] and RNA; other nucleotides such as ATP that are vital components of energy metabolism; enzyme cofactors. Phosphorus also has a role in regulating acid-base balance.

==Roles in the Body==

==Roles in the Body==

In terms of its structural role, the main function of phosphorus is, when combined with calcium, in the '''formation of hard structures such as bones and teeth'''. Phosphorus is also involved in many key processes such as membrane integrity and provision of so-called energy-rich compounds vital to energy metabolism. It is also a component of enzyme cofactors. These are relatively small organic molecules, associated with larger enzyme molecules, which are necessary for the enzymes to function effectively. The cofactors often combine with and then release molecules or fragments of molecules as part of the overall enzymatic process. Dietary phosphorus absorption is controlled principally by parathyroid hormone (PTH), which regulates the renal production of 1,25-dihydroxyvitamin D. The vitamin stimulates the absorption of phosphorus from the small intestine similar to the effect on [[Calcium - Nutrition|calcium]].     

In terms of its structural role, the main function of phosphorus is, when combined with calcium, in the '''formation of hard structures such as bones and [[Teeth - Anatomy & Physiology|teeth]]'''. Phosphorus is also involved in many key processes such as membrane integrity and provision of so-called energy-rich compounds vital to energy metabolism. It is also a component of enzyme cofactors. These are relatively small organic molecules, associated with larger enzyme molecules, which are necessary for the enzymes to function effectively. The cofactors often combine with and then release molecules or fragments of molecules as part of the overall enzymatic process. Dietary phosphorus absorption is controlled principally by [[parathyroid hormone]] (PTH), which regulates the renal production of 1,25-dihydroxyvitamin D. The vitamin stimulates the absorption of phosphorus from the small intestine similar to the effect on [[Calcium - Nutrition|calcium]].     

==Consequences of Phosphorus Deficiency==

==Consequences of Phosphorus Deficiency==

===Cat:===   

===Cat:===   

As with the dog there are very few studies of dietary phosphorus deficiency in cats but the '''effects on skeletal development will be expected to be similar to those seen in dogs'''. In adult cats clinical signs of deficiency including haemolytic anaemia, permanent flexion of the hind legs, apathy and metabolic acidosis were observed in those animals receiving a diet containing 0.21% phosphorus and 0.83% calcium (DM basis). The diet therefore had a very high Ca:P ratio of about 4:1<ref>Kienzle, E, Thielen, C, Pessinger, C (1998). “Investigations on phosphorus requirements of adult cats”. J Nutr. 128 (suppl):2598S-2600S.</ref>. The importance of the Ca:P ratio is shown by the observation from the same study that no clinical signs occurred when the dietary concentrations of calcium and phosphorus were both 0.21% DM.   

As with the dog there are very few studies of dietary phosphorus deficiency in cats but the '''effects on skeletal development will be expected to be similar to those seen in dogs'''. In adult cats clinical signs of deficiency including [[Regenerative and Non-Regenerative Anaemias|haemolytic anaemia]], permanent flexion of the hind legs, apathy and metabolic acidosis were observed in those animals receiving a diet containing 0.21% phosphorus and 0.83% calcium (DM basis). The diet therefore had a very high Ca:P ratio of about 4:1<ref>Kienzle, E, Thielen, C, Pessinger, C (1998). “Investigations on phosphorus requirements of adult cats”. J Nutr. 128 (suppl):2598S-2600S.</ref>. The importance of the Ca:P ratio is shown by the observation from the same study that no clinical signs occurred when the dietary concentrations of calcium and phosphorus were both 0.21% DM.   

==Toxicity==

==Toxicity==

===Dog and Cat:===   

===Dog and Cat:===   

There is very little information on the effects of excessive intakes of phosphorus per se in dogs and cats. Where adverse effects have been reported they are almost invariably linked to a low Ca:P ratio or a deficiency of calcium rather than an excess of phosphorus itself. If a diet has a satisfactory Ca:P ratio it is likely that a fairly wide range of phosphorus intakes will be tolerated, especially for adult animals with normal kidney function. Animals with compromised kidney function, dietary phosphate and protein restriction may be required [link to WikiVet Kidney Failure].

There is very little information on the effects of excessive intakes of phosphorus per se in dogs and cats. Where adverse effects have been reported they are almost invariably linked to a low Ca:P ratio or a deficiency of calcium rather than an excess of phosphorus itself. If a diet has a satisfactory Ca:P ratio it is likely that a fairly wide range of phosphorus intakes will be tolerated, especially for adult animals with normal kidney function. Animals with [[:Category:Renal Failure|compromised kidney function]], dietary phosphate and protein restriction may be required.

==Dietary Sources==

==Dietary Sources==

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition GGP]]

[[Category:To Do - Nutrition preMars]]