Vitamin D Metabolism in Exotics Flashcards
Outline the process by which active Vitamin D is produced by an animal.
7-dehydrocholesterol is converted by UVB to pre-cholecalciferol then spontaneously turns into cholecalciferol intracellularly (secreted to extracellular space and then binds to vitamin d binding protein for transport to the liver) or cholecalciferol/ergocalciferol(plant form) can be taken up in the diet. Cholecalciferol is then hydroxlated in the liver to 25-hydrocholecalciferol and further hydroxlated in the kidney (megalin transports it to renal tubules) to form 1,25-dihydrocholecalciferol or active vitamin D3.
How might the husbandry needs of a lizard living predominantly underground to a parrot living in the rainforset canopy differ with regards to vitamin D?
Parrot would need more UV and underground lizard more dietary sources of vit D.
How does the parathyroid gland influence calcium homeostasis.
Low calcium leads to release of PTH.
Effects of PTH: increased synthesis of active D3 by the kidney, increased Ca2+ resorption and P042- excretion from the kidney, bone reabsorption (osteoclasts) which is synergistic with vitamin D here. Vitamin D increased dietary calcium intake.
Which cells are resposible for calcitonin secretion?
C cells in the PT and ultimobranchial bodies in birds.
What would a blood profile show in an animal with MBD?
High PTH and normal Ca2+. MBD is a result of Ca homeostasis at the expense of bone calcium levels
What are some species specific considerations when it comes to husbandry/diets?
Rabbits excrete lots of Ca2+ in their urine so are prone to calcium bladder stones
Dog/Cat food contains lots of dietary vitamin D so don’t feed to exotics
Egg laying animals must increase blood calcium a lot prior to laying.
How might free living animals develop MBD?
Antropogenic changes leading to change to habitats and diets.
What are some considerations for bird diets?
Seeds are deficient in many vits and mins and high in fat which birds dont need as they aren’t active. Feed pellets instead.
Fruit and Veg is OK in small quantities as long as they dont fill up the animal too much.
