'Nutritional or Metabolic' Bone Disease Flashcards
What is endochrondal ossification?
Cartilage changing into bone
Bone can act as a store of Ca, what vital processes does it help?
Muscle contraction, esp heart - neuromuscular function
Coagulation cascade
Ca influx - cell signalling
What is the presentation of Bone disease?
Young animal (can be an adult) Deviation of limbs, poor posture, weakness Axial skeleton as well as appendicular Dietary problems Comparison to litter mates Pathological fractures Generalised disease (no history of trauma)
What is characteristic in juvenile rads?
Evident Epiphyseal growth plates, wide gaps in joints, lot of layers of hyaline cartilage
What age are bones skeletally mature in a dog?
9 months
Muscles mature at 16/18 months - long time before the bones are supported!
How are the Ca serum levels protected?
Highly protected - Ca robbed from hydroxylapatite from bone
What problems related to Ca that affects juvenile patients?
Calcium deficient animals
Secondary Nutritional hyperparathyroidism
What happens when there is decreased plasma Ca in the body?
Signals to parathyroid hormone –> releases PTH –> increases Ca absorption from intestines and decreases Ca excretion from kidneys—-> increases plasma Ca which feedbacks to PTH
What happens in Secondary nutritional hyperparathyroidism?
Aetiology, CS, who does it affect most?
- Low dietary Ca drives high PTH levels
- Serum Ca is protected so bones are targeted
(Plasma bound vs ionised Ca - need to work out the ionised value to help this syndrome)
CS: Bones malformed, poorly formed
(PTH also absorbs from intestines and stops as much excretion from kidneys)
Problem for growing animals (young) and exotics
Why is the serum Ca so protected?
PTH works to keep Calcium in the right place - keep heart and brain functioning
What would you notice on the rads for hyperparathyroidism?
Pathological fracture
Low contrast inside bones to cortices - not as radio-opaque - lot of black areas
What happened to the Tiger to cause him to develop Secondary nutritional hyperparathyroidism?
Removed from mother too early - no milk (no ca)
Then fed raw meat - increase in phosphate, low in ca
What is secondary Renal hyperparathyroidism?
There is chronic renal failure in adults (usually dietary ca is not too low in adults)
- Decreased activation of vit D (involved with a lot of organs - diff forms - activated by body/sunlight)
- Lowered phosphate excretion so binds to plasma ca - serum ca is lowered which drive PTH UP!!
Increased PTH drive and effects on bones
ie. soft mandible
What exotic species get metabolic bone disease?
Reptiles and Chelonians
Low dietary availability of Ca, decreased activation or availability or vit d
What is the common presentation for metabolic bone disease?
History: lethargy + weakness (can’t lift tail), pliant mandible, abnormal posture, WL, decreased appetite, laying eggs?
Clinical exam: Activity, movement/lameness - joint swelling, limb swelling, muscular tone + atrophy
