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Rumi Endocrine 2

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sihirlifil's version from 2018-02-23 14:10

Calcium intro

Question Answer
_________% of total body Ca is found int the skeleton99%
Ca exists in 3 forms in blood:Ionized 50%
Protein-bound 45%
Complexed to anionic salts 5%
Which form of Ca is biologically active?Ionized
How does pH affect ionized Ca?Alkalosis --> DECR Ca
Acidosis --> INCR Ca (like Ca imitates H+)
Physiologic fxns of CaNM excitability
Musc contraction
Blood coag
Hormone secretion
(change in pH affects these fxns!)
Neuromuscular fxn: how is a nerve impulse transmitted?Ca2+ --> dampen Na channels --> nerves less excitable
Hypocalcemia does what to nerve excitability?INCREASES --> tetany
What does Ca2+ do at the neuromusc jxn?Promotes release of acetycholine
Hypocalemia does what at the neuromusc jxn?Causes NM blockade --> Paresis
Hypocalcemia in nerve conduction (graph)
How does hypocalcemia affect muscle types?Skeletal --> paresis
Cardiac --> decreased ejection volume
Smooth --> hypotension
What's the role of Ca2+ in musc contraxn?Skeletal: troponin binding
Smooth: Calmodulin-Ca --> MLCK
Ca2+ role in CNSNeurotransmitter release
HYPO = Coma
Ca2+ role in glucose regulationInsulin release
HYPO = hyperglycemia
Where are calcium stores?Bone, Dietary in GI tract
Calcium losses come from?Bone growth (esp young)
Fetus (esp late gestation)
Lactation
How is Ca2+ regulated?TIGHTLY in ECF
3 1ry controllers of Ca2+ homeostasisPTH
Calcitonin
Vit D
Effects of PTH releaseMobilizes bone mineral
Promotes retention of Ca2+ in kidney & activation of vit D
Promotes loss of P in urine & saliva
Net effect = increased ionized Ca2+
(Ca homeostasis pic)
Vitamin D: produced where? what happens to it?Inactive form 25-OH D produced by liver --> activated to 1,25(OH)2D in kidney by PTH, hypoCa2+, and hypoP
Actions of Vit DHelps PTH mobilize bone mineral
Incr Ca2+ & P absorption from GI tract
Net effect incr ionized Ca2+
What happens when ionized Ca2+ is high?Calcitonin released --> promotes deposition of calcium in bone & loss of calcium in urine
Net effect reduced ionized Ca2+
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Bovine Periparturient Paresis

Question Answer
Bovine periparturient paresis akaMilk Fever
Primarily a dz of?Dairy cattle
When do beef cattle & SR usually get hypoCa2+?Pre-partum!
When does milk fever occur?Within 1-2d of calving. 75% within 24h
Risk factors for milk feverHigh BCS, older age
Channel Island breeds (Jersey, Guernsey)
Poor nutrition/high Ca2+ dry cow diets
High-producing cows
Hypomagnesemia, metabolic alkalosis
Within 72 hours of parturition
CS before calving(beef cows, SR) Weakness, recumbency
CS during calvingDystocia, cervix not dilated, weak contractions
CS after calving(traditional signs)
Common CS of subclinical hypoCa2+Reduced feed intake
Poor rumen & intestinal motility
Poor productivity
Higher risk of 2ry infxn
Common CS of clinical hypoCa2+Twitching/tremors
Progressive musc weakness, smooth/skel musc paralysis
Dystocia
Recumbency
How much calcium is pulled into milk at onset of lactation?10x the ECF content within several hours!
(10L colostrum) * (2.3 g Ca/L) = 23 g Ca... the plasma Ca pool = 2.5 g! yikes
Milk fever caused by? results in?Onset of heavy milk production. Depletes serum Ca2+ so rapidly that hormonal controls cant keep up
Blood calcium drops so low that musc & nerve fxn are compromised --> paresis
Bone resporption of Ca2+ takes how long? Intestinal?Bone: 48h
Intestines: 24h
PTH doesnt work as well in what condition?Alkaline blood pH
Displaced abomasum, high K forages
_________ pH promotes hypocalcemia... why?Alkaline
Conformational structure of PTH receptor changes! & vit D activation is dependent on PTH
Milk Fever Stage 1: CSNerve condxn: Hypersensitive, irritable
NM: weight-shifting, weakness
Cardiac mm: Tachycardia
Milk Fever Stage 2: how quickly does it ensue?QUICK! sometimes within 1 hr
Milk Fever Stage 2: CSSternal recumbency w/ head tucked, S-shaped neck
Flaccid paralysis, muscle fasciculations
Tachydardia 80-90 BPM, decr intensity of heart sounds, weak contractility, decr ejection vol, BP drops (but Symp NS maintains by incr HR & vasoconx)
Poor perfusion: subnorm rectal temp, cold extremities
Mild bloat, GI stasis
Urine retention
Slow PLR
What stage of milk fever?
Stage 2
Milk Fever Stage 3: CSLateral recumbency, progressive loss of consciousness
Severe bloat
Heart sounds very quiet, severe tachycardia
Coma --> death
What stage of milk fever?
Stage 3
_________ soon follows stage 3Respiratory or cardiac arrest --> death
Complications from Milk Fever: Flaccid paralysisBloat
Aspiration pneumonia
Complications from Milk Fever: RecumbencyMusc compression, rupture
Skeletal injuries
Peripheral nerve dmg
Clin Path: HypoCa2+ =<7.5 mg/dL (RR 9.7-12.4)
Ca2+ of 5.5-7.5 mg/dL = Stage1
Ca2+ of 3.5-6.5 mg/dL = Stage2
Ca2+ of <2.0 mg/dL = Stage3
Clin Path: when do you collect blood?BEFORE tx! otherwise can interfere
Clin Path: Ionized Ca? P? Glc?Ionized Ca2+ = LOW
Hypophosphatemia (PTH dumps P in urine)
Hyperglycemia (Ca needed for insulin release)
Tx: Stage 1Oral Ca2+ gels, SQ calcium gluconate
Tx: Stage 2 & 3IV calcium gluconate
Oral calcium gels composed of? How do oral calcium gels help?Calcium chloride (caustic but more bioavailable) or proprionate (also energy source!) (25-100 g of calcium)
Rapidly raise Ca in Intestine for absorption
Calcium gluconate: composed of? Route of admin?Calcium borogluconate 23%
SC or IV
How much IV Ca2+ can you give?1g per 45kg BW (most 500mL preps contain 8-12g)
What happens if you give IV calcium too quickly?STOPS THE HEART! give over 15 min & auscult during admin
Does milk fever relapse? why?25-30% relapse within 24-48h, more common in older cows
Due to deficiencies in magnesium, phosphorous, potassium
Prevent w/ oral Ca gels, SC Ca
If you want to give a dextrose-containing solution...Do NOT give SUBQ!!!
What is CMPK?
Signs of successful therapyImproved smooth musc fxn: eructation, urination, defecation
Improved cardiac musc fxn: stronger heart sounds, decr HR
Improved skel musc fxn: Standing, fasciculations stop
Additional nursing care for milk feverGood footing!
Keep sternal, don't get them up too soon. If need prolonged recumbency, roll from side-side
Provide water!
What are these? why helpful?
Hobbles! prevent splay-legging
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