Metabolic and Nutritional Diseases Flashcards
Primary copper deficiency is due to:
Inadequate dietary copper concentration
Secondary copper deficiency can be due to:
Iron, sulfates, zinc - make copper poorly absorbed
Molybdenum in excess - binds to copper and lowers copper bioavailability
Risk factors to copper deficiency
- All milk diets (low copper levels)
- Young animals
- High growth rate
- Animals on forage diets instead of concentrate diets
- Fescue plants impair copper absorption
- Lack of Supplementation
- Breed - Simmentals are overrepresented
Why do cows need copper?
- Involved in a variety of enzyme systems (superoxide dismutase, cytochrome oxidase, lysol oxidase, ascorbic acid oxidase, ceruloplasmin)
- Required for iron metabolism
- Prevention of cellular oxidative damage
Copper Deficiency Syndromes - presents in a variety of clinical signs, what is the MC? Why does it happen?
Hypochromotrichia - lightening of hair coat - morphologic and functional changes in the melanocytes (reduction of tyrosinase activity)
Diarrhea is a sign of copper deficiency - why do we see it?
Mucosal and villous atrophy
Crypt elongation + goblet cell hyperplasia –> unable to absorb things appropriately
Cytochrome oxidase does not work
Mitochondrial change - cells will not function appropriately chronically
Why do we see spontaneous fractures in copper deficiency?
Irregular thickness of physis joint deformation, and bone fragility due to decreased lysyl oxydase function and decreased Cu-ATPase.
What kind of CNS abnormalities are seen with copper deficiency and why do they occur?
Sway back + enzootic ataxia and weakness in back legs
Cows born with oligodendrocyte dysfunction - NOT acquired
Decrease cytochrome oxidase and decreased superoxide disumutase in utero
What kind of anemia is present on blood work in an animal with copper deficiency?
Secondary iron deficiency anemia - macrocytic, hyperchroic anemia
Why do we see anemia in copper deficienct cows?
Decrease in ceruloplasmin and iron oxidation
Decrease in ALA dehydrase and heme syntehsis
Decrease in erthrocyte survivability
Protein cytoskeleton alterations
Increased cell viscosity via lipid loading
Clinical manifestations of reduced repro performance in copper defiency include:
Increased time to puberty
Decreased conception rates
Anestrus
Fetal resoprtion
Decreased semen quality
Copper deficiency can compromise the immune system. How does this represent itself in a herd?
When cows start becoming infected with pathogens that are unlikely to cause disease normally.
What is the timeline of copper deficiency in regards to where it gets depleted first, and when clinical signs start to show up
First copper ges depleted from tissues, then plasma, then from the enzyme systems (biochemical function effected).
When copper gets depleted from tissues and plasma, we often do not see any C/S yet. However, once there is not enough copper for all the normal enzyme systems and it effects biochemical function, we start seeing disease.
With copper - you have to really depelete body stores before animal shows C/S.
Where is copper stored in? What significance does this play in our diagnosis of copper deficiency?
Stored in the liver - if we are looking for early deficiency - liver is our best sample to detect copper deficiencies.
Once copper gets depleted from the liver, plasma levles will drop off and clinical signs start showing - so testing blood levels will diagnose copper deficiency at this point.
When testing cows for copper deficiency, can you test cows from just one pasture, if you have 15 differnt pastures?
No - each pasture is a different herd that NEEDS to be tested becuase each pasture has different micronutrients in the soil.
Treatment and prevention of copper deficiency
Copper supplementation:
dietary - test for copper, molybdenum, sulfer; adequate feed levels not always enough (remmeber inhibitors)
Injection
Copper oxide needles for sustained copper release
Copper boluses
Reason for selenium deficiency?
Inadequate intake
Syndromes that result from selenium deficiency
- Nutritional myodegeneration
- Decreased reproductive performance
- Retained fetal membranes
- Increased disease susceptibility
- Increased gram negative mastitis
- General ill thrift
During what season (drought or wet) will make selenium less available in plants?
drought/drying will make selenium less available
Selenium is requried in which enzyme system?
What vitamine does in funciton in concert with?
Glutathione peroxidase (GSX-Px) - reduces peroxides and super oxides within the cytosol
Functions in concert with vitamine E
Why do we tx selenium deficiencies with vitamin E right away, instead of just selenium?
Vitamin E spares glutathione peroxidase - meaning it becomes an antioxidant right away.
In contrast, selenium needs to be incorporated in the glutathion peroxidase enzyme in order to become an antioxidant, which takes 7-10 days.
Selenium deficiency can cause nutritional myodegeneration - what is this disease called?
White muscle disease
White muscle disease affects ____ and ____ muscles in neonates; and ____ muscles in yearling/juveniles.
cardiac; diaphgramatic
Skeletal
What is the diagnostic sample of choice in dx selenium deficiency?
Whole blood
When collecting whole blood samples to dx selenium deficiency, what tube do we use?
Royal blue top tube - plastic with plastic stopper
Some micronutrients can interact with the rubber stoppers, so you want plastic.
Serum chem on white muscle disease will show massive increases in ___ and ____.
High CK and AST
T/F: Liver biopsies are more useful in selenium deficiencies than copper deficiencies.
False - liver biopsies are more userful in copper deficiencies
Treatment and Prevnetion of selenium deficiency
- Injectable selenium (must be incorporated into glutathione peroxidase to be metabolically active - takes 10-14 days)
- Injectable vitamine E (more immediate results)
- Commercial selenium products
- Dietary supplementation
T/F: An injectable selenium product that is advertised to have vitamine E as well is enough to tx selenium deficiency.
False - not enough vitamine E to be a useful antioxidant - need to give a PURE vitamin E injectable product.
Vitamin A is required for:
Normal bone growth
Epithelialization
Regeneration of rhodopsin (required for night vision)
T/F: Night blindness is a common C/S in vitamin A deficiency.
True
Reasons of vitamin A defiency
Lack of intake
Sun cured forages (poor quality roughage, prolonged sotrage of roughage, no/little roughage)
Clinical signs of vitamin A deficiency:
- Encephalopathy - coritcal based neurologic signs
- Night blindness
- Incoordination, weakness
- Repro failure
- Squamous metaplasia
- Hyperkeratinization of the skin, rumen, reticulum, and preputial membrane
Dx vitamin A deficiency:
Increase in CSF pressure- not commonly checked
Decrease in plasma and liver vitamin A
Decrease in liver carotene
Tx of vitamin A deficiency
Vitamin A supplementation (injectable!)
High quality hay
Common name of parutrient paresis/hypocalcemia
Milk fever
Why does milk fever happen?
Failure of homeostatic mechanisms to control blood calcium levels.
Results from the onset of lactation in older high-producing dairy cows.
When blood calcium drops, what happens to PTH and what does PTH do?
PTH increases - which stimulates mobilization of calcium and phosphorous from the bone, and simtulates calcium resorption and phosphate excretion by the kidney.
Increased secretion of PTH also causes synthesis of 1,25 Vit D in the kidney which stimulates calcium binding protein, which increases intestinal absorption of calcium.
T/F: High calcium diets in dry cow ration can cause milk fever after parturition with the onset of lactation.
True
T/F: Calcitonin limits bone resorption and favors calcium deposition, and drives urine excretion of calcium.
True
Low Ca prepartm diet _____ PTH secretion.
Low magnesium diet ___ the normal response to PTH.
Increases
Blunts
Metabolic alkalosis _____ renal sensitivity to PTH.
Metabolic acidosis _____ in bone, favoring the function of PTH.
decreases
buffers
PTH works best at a slightly _____ pH.
acidic - around 7.3
A dry cow requires 10-12 g of calcium/day. A lactating cow requires approximately ___g/____kg of milk.
50g/40kg
Most milk fever cows present within the ____ week post calving.
First
__% of cattle relapse with milk fever. How can we prevent relapse?
20%; give calcium via IV and sunQ
Predisposing factors to milk fever
- Older cows
- Fewer active bone cells
- PTH receptors decrease with age
- High milk producers
- Prepartum diets (high phosphorus and calcium)
- Anion cation balance
- Na/K alkalinizing - bad
- (Cl/sulfur acidifying - promote bone resorption - good)
- Jersey breed
- Decrease in intestinal 1,25 vit D receptors
During midlactation, a cow depends almost entirely on _____ calcium abosprtion to replenish blood calcium content.
Intestinal
Hypomagensemia can precipitate midlactation hypocalcemia. What seasons is this most common?
Spring and fall in pasture based dairies
Estrogen ___ bone resorption.
Inhibits
Describe the three stages of milk fever
- Stage 1
- Cow is standing
- Mild signs often missed
- Nervousness, agitation, excitement, tetany
- Muscle tremors, anorexia, stiff gait
- Stage 2
- Sternal recumbency
- “classic signs” - head to side, elevated HR, cold extremities
- Stage 3
- Lateral recumbency
- Comatose, faccid, heart hard to auscult, severe bloat, death
General clinical presentaiton of milk fever
- Anorexia
- Rumenal atony
- Generalized weakness
- Circulatory collpase - decreased CO by 60%
- Tachycardic, weak heart sounds
- Dry muzzle (sweat glands not working)
- Mental depression
- Hypothermia - cannot regulate body temp b/c not circulating
- May be hypothermic if sitting in the sun
- Dilated sluggish pupils
- Scant feces (GI not moving)
Hypocalcemia in ewes is most often seen when? Why?
Late gestation - stress induced, often concurrent with preg tox
Hypocalcemia can occur both in the ____ and _____ period in goats.
Prepartum and postpartum
Dx milk fever in small ruminants:
Recumbency with typical history is very suggestive.
Can check serum calcium - diagnostic test of choice - however we do not often run blood calcium levels
Magnesium should be elevated
Phosphorus typically low
T/F: Ionize calcium levels are a much better dictator of the cows status than total calcium.
True