Changes

==Roles in the Body==

==Roles in the Body==

In terms of its structural role, the primary role of calcium is, when combined with [[Phosphorus - Nutrition|phosphorus]], in the formation of hard structures such as bones and teeth. Low dietary levels are therefore associated with '''severe skeletal problems'''. Calcium (especially in its ionised form) is also involved in numerous key intracellular and extracellular processes such as blood clotting, the transmission of nerve impulses, muscle contraction, maintenance of vasomotor tone, and cellular signalling. The level of calcium in the blood plasma is crucial to these functions and is under tight [[Calcium#Calcium Homeostasis|homeostatic control]]. Dietary calcium absorption is controlled by parathyroid hormone (PTH), which regulates the renal production of 1,25-dihydroxyvitamin D. This vitamin stimulates the absorption of calcium from the intestine, so by carefully controlling its production, calcium absorption can be regulated up at low intake and down at high intake. Nevertheless, Dobenecker<ref>Dobenecker, B. (2002). “Influence of calcium and phosphorus intake on the apparent digestibility of these minerals in growing dogs”. J Nutr. 132 (suppl):1665S-1667S.</ref> reported that beagle puppies younger than 4 to 5 months were unable to adjust the digestibility of calcium in relation to either excess or insufficient intakes. This makes it particularly important to adjust the supply of calcium in line with the dog’s requirements.

In terms of its structural role, the primary role of calcium is, when combined with [[Phosphorus - Nutrition|phosphorus]], in the formation of hard structures such as bones and teeth. Low dietary levels are therefore associated with '''severe skeletal problems'''. Calcium (especially in its ionised form) is also involved in numerous key intracellular and extracellular processes such as blood clotting, the transmission of nerve impulses, muscle contraction, maintenance of vasomotor tone, and cellular signalling. The level of calcium in the blood plasma is crucial to these functions and is under tight [[Calcium#Calcium Homeostasis|homeostatic control]]. Dietary calcium absorption is controlled by parathyroid hormone (PTH), which regulates the renal production of 1,25-dihydroxyvitamin D. This vitamin stimulates the absorption of calcium from the intestine, so by carefully controlling its production, calcium absorption can be regulated up at low intake and down at high intake. Nevertheless, Dobenecker<ref>Dobenecker, B. (2002). “Influence of calcium and phosphorus intake on the apparent digestibility of these minerals in growing dogs”. J Nutr. 132 (suppl):1665S-1667S.</ref> reported that beagle puppies younger than 4 to 5 months were unable to adjust the digestibility of calcium in relation to either excess or insufficient intakes. This makes it particularly important to adjust the supply of calcium in line with the dog’s requirements.

 

==Consequences of Calcium Deficiency==

==Consequences of Calcium Deficiency==

[[File:134957 Lat lumbar spine.jpg|200px|right|thumb|A 2 month old Great Dane puppy with a history of eating an unbalanced diet. The bone density is overall decreased with a poor corticomedullary distinction.]]

[[File:134957 Lat lumbar spine.jpg|200px|right|thumb|A 2 month old Great Dane puppy with a history of eating an unbalanced diet. The bone density is overall decreased with a poor corticomedullary distinction.]]

===Dog:===

===Dog:===

The classic syndrome of calcium deficiency in dogs is known as '''nutritional secondary hyperparathyroidism (NSHP)''', which is caused by a persistent decrease in circulating calcium in the blood (hypocalcaemia). This, in turn, stimulates the release of parathyroid hormone (PTH), which increases the reabsorption of bone to provide the calcium required to maintain a normal ionised calcium (iCa) blood concentration. The inevitable consequence is a major decrease in bone mineral content, which can lead to skeletal problems such as <span style="color:red">pathologic fractures (Dan to provide a radiograph)</span><ref>Hazewinkel, HAW, van den Brom, WE, Vanꞌt Klooster, AT, Voorhout, G, Van Wees, A (1991). “Calcium metabolism in great Dane dogs fed diets with various calcium and phosphorus levels”. J. Nutr. 121 (suppl):S99-S106.</ref>. This is particularly serious for young puppies, where active growth of the skeleton is occurring. The condition typically results from feeding diets deficient in calcium such as those composed mainly of meats, since all meats (including offal) have a very low calcium content. The ratio of calcium to phosphorus is also important and it is the low ratio in these foods (i.e. Ca:P much less than 1:1) that contributes to the adverse effects because the '''high phosphorus level inhibits calcium absorption'''.

The classic syndrome of calcium deficiency in dogs is known as '''nutritional secondary hyperparathyroidism (NSHP)''', which is caused by a persistent decrease in circulating calcium in the blood (hypocalcaemia). This, in turn, stimulates the release of parathyroid hormone (PTH), which increases the reabsorption of bone to provide the calcium required to maintain a normal ionised calcium (iCa) blood concentration. The inevitable consequence is a major decrease in bone mineral content, which can lead to skeletal problems such as pathologic fractures <ref>Hazewinkel, HAW, van den Brom, WE, Vanꞌt Klooster, AT, Voorhout, G, Van Wees, A (1991). “Calcium metabolism in great Dane dogs fed diets with various calcium and phosphorus levels”. J. Nutr. 121 (suppl):S99-S106.</ref>. This is particularly serious for young puppies, where active growth of the skeleton is occurring. The condition typically results from feeding diets deficient in calcium such as those composed mainly of meats, since all meats (including offal) have a very low calcium content. The ratio of calcium to phosphorus is also important and it is the low ratio in these foods (i.e. Ca:P much less than 1:1) that contributes to the adverse effects because the '''high phosphorus level inhibits calcium absorption'''.

 

====Recognised Syndromes related to Calcium Deficiency====

====Recognised Syndromes related to Calcium Deficiency====

#'''Skeletal malformation''': Hazewinkel et al.<ref>Hazewinkel, HAW, van den Brom, WE, Vanꞌt Klooster, AT, Voorhout, G, Van Wees, A (1991). “Calcium metabolism in great Dane dogs fed diets with various calcium and phosphorus levels”. J. Nutr. 121 (suppl):S99-S106.</ref> described severe skeletal problems in Great Dane puppies fed diets with 0.55% calcium on a <span style="color:red">dry matter basis (DM) (hotline to definitions/glossary of terms)</span>. However Nap et al.<ref>Nap, R, Hazewinkel, HAW, van den Brom, WE (1993). “45Ca kinetics in growing miniature poodles challenged by four different dietary levels of calcium”. J. Nutr. 123:1826-1833.</ref> found no abnormalities in miniature poodle puppies (13-25 weeks) fed 0.33% calcium on DM. Nevertheless, in the same experiment<ref>Nap, R, Hazewinkel, HAW, van den Brom, WE (1993). “45Ca kinetics in growing miniature poodles challenged by four different dietary levels of calcium”. J. Nutr. 123:1826-1833.</ref>, NSHP was observed when a very low level of 0.05% calcium was fed. It is clear that giant, rapidly growing breeds are more sensitive to restrictions in dietary calcium.     

#'''Skeletal malformation''': Hazewinkel et al.<ref>Hazewinkel, HAW, van den Brom, WE, Vanꞌt Klooster, AT, Voorhout, G, Van Wees, A (1991). “Calcium metabolism in great Dane dogs fed diets with various calcium and phosphorus levels”. J. Nutr. 121 (suppl):S99-S106.</ref> described severe skeletal problems in Great Dane puppies fed diets with 0.55% calcium on a <span style="color:red">dry matter basis (DM) (hotline to definitions/glossary of terms)</span>. However Nap et al.<ref>Nap, R, Hazewinkel, HAW, van den Brom, WE (1993). “45Ca kinetics in growing miniature poodles challenged by four different dietary levels of calcium”. J. Nutr. 123:1826-1833.</ref> found no abnormalities in miniature poodle puppies (13-25 weeks) fed 0.33% calcium on DM. Nevertheless, in the same experiment<ref>Nap, R, Hazewinkel, HAW, van den Brom, WE (1993). “45Ca kinetics in growing miniature poodles challenged by four different dietary levels of calcium”. J. Nutr. 123:1826-1833.</ref>, NSHP was observed when a very low level of 0.05% calcium was fed. It is clear that giant, rapidly growing breeds are more sensitive to restrictions in dietary calcium.     

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition GGP]]

[[Category:To Do - Nutrition GGP]]

[[Category:To Do - Nutrition Questions]]

[[Category:To Do - Nutrition Questions]]