Vitamin D

What is a major factor that contributes to the formation of vitamin D?

Exposure to sunlight/UV

What is the only form of vitamin D that is biologically active?

1,25 dihydroxycholecalciferol

What is the main deficiency symptom of vitamin D?

Disturbance in absorption/metabolism of calcium and phosphorous. Insufficient bone calcification. Malformation, etc.

What are some unique symptoms of vitamin D toxicity besides reduced feed intake, growth rate, etc.? Study these.

-Reduced liver weight -excess calcium in blood (hypercalcemia) -Calcification of heart, aorta, lung, kidneys -dehydration, vomiting, fatigue. -reduced weights of radius and ulna (bones)

In adult animals with a vitamin D deficiency, osteomalacia occurs. What is this?

Adult version of rickets. Decreased mineral content and softening of bone.

What does vitamin D do in the kidneys?

Calcium conservation/balance (making sure it stays, or in some instances, excretes). -Also increases phosphorous reabsorption.

What are some natural sources of vitamin D?

Cod liver oil Egg yolk Beef liver Sun cured alfalfa UV-irradiated mushrooms

What are important factors that effect the production of vitamin D by an animal?

Housing conditions, hair coat

Where is vitamin D stored?

In the liver for max 3 months

What is the toxicity of vitamin D?

It is the most toxic of any vitamin. toxicity usually results in a formulation error. Feeding lots of vitamin D to young pig resulted in death in 4 days.

Do dogs absorb sunlight?

No.

What does vitamin D do for the bones?

Mobilization of Calcium. (appears in nuclei of osteoblasts/osteocytes)

Would a light haired, older alpaca convert sunlight to vitamin D more efficiently or a black haired young alpaca?

Older light haired. Older animals do it better, and light hair makes easier to convert. Vitamin D deficiency is a problem in alpacas bc of thick fur.

What is the plant form of vitamin D? What is the animal form? Are these provitamins or vitamers?

Plant: ergocalciferol D2 Animal: cholecalciferol D3 They are provitamins.

A unique subclinical sign of vitamin D deficiency includes lack of bone calcification and proliferation of ephyseal cartilage. What is ephyseal cartilage?

Poor formation of the long bone, on tne ends.

Vitamin D2 and D3 are equal in all species except which one? What do they require?

Poulty. Require D3, cholecalcierol. Missing a mechanism for the conversion.

Historically, what was vitamin D used as? Why?

Rat poison. because it hardens the lungs and heart tissue. calcifies the tissue, heart stops beating and lungs can't expand. suffocation

Another subclinical sign of vitamin D deficiency is --- and --- fractures.

Rib and vertebra fractures. mainly just thin bones.

What is the process of conversion of sunlight to useful vitamin D?

Skin synthesizes 7-dehydrocholesterol from sun. Forms cholecalciferol (D3). Goes to liver, liver produces 25-hydroxyvitamin D3. Goes to kidney, produces 1,25 dihydroxyvitamin D3. Maintains calcium balance in body. Active form of vitamin D.

What are the most important tissues in the metabolism of vitamin D?

Skin, liver, kidneys. some intestines

From vitamin D deficiency, Rickets can occur in young animals. What is this?

Soft bones. bones don't develop properly in young animals. log term impact

How is vitamin D usually supplemented? Why?

Subcutaneously because it has the opportunity to diffuse and must be absorbed slowly.

What risk does vitamin D deficiency increase in dogs?

Congestive heart failure

Vitamin D deficiency can also result in elevate serum alkaline phosphatase. What is this and why is this?

Enzyme that dephosphorylats. Because rapid bone turnover.

Do foods contain any vitamin D?

Yes, most foods contain small amounts. Some are fortified (milk, cereal)

What does 1,25 (OH)2 D3 do in the intestines?

induces synthesis of calcium binding protein. required for active calcium uptake. Also stimulates transport of phosphorous and magnesium