Equine Physiology Flashcards

Question

RBC time in capillaries

Answer 1

at rest = ~1s in cap w/ exercise = 0.38-0.40s in cap

Answer 2

- Left laryngeal hemiplegia (LLH) - dorsally-displaced soft-palate (DDSP) - epiglottic entrapment - dynamic pharyngeal collapse

Answer 3

when placed on bit with ↑ poll flexion, repeatable DDSP + coughing but no other noise was ever apparent

Answer 4

Lung Borders: - rib 6 ccjxn - rib 11 mid-thorax - rib 16 at tuber coxae level normal sounds = slight air movement re-breathing bag - bag over nostrils →→→ ↑ RR +/- depth → ↑ ability to auscult abnormal lung sounds ## Footnote cannot hear lung sounds through back musculature of horses

Answer 5

Wheezes - indicative of ↓ airway d/t bronchoconstriction or exudate - high-pitched musical sounds similar to pipe organ Crackles - indicative of rapid alveolar opening, alveoli prev. collapsed d/t exudate - indicatived of exudate which moves around w/ resp resulting in rattling/popping/crackling sound - harsh sound similar to cellophane

Answer 6

- poor mucociliary clearance 2nd to viral infxn - pneumonia - COPD (or RAO) - exercise-induced pulmonary hemorrhage (EIPH)

Answer 7

1) resp system thought to not be trainable - VE does not change with ↑ fitness (only mild increase in respiratory muscle) 2) ↓ RR w/ ↑ fitness thought to be more of a function of: - ↑ CV fitness - ↑ IM fitness, ↑ aerobic enzyme capacities - ↑ thermoregulatory capacity 3) same VO2 at given WL 4) ↑VO2max by 15-20%

Answer 8

CHO > fat > protein -CHO from : - grains (starch) eaten as concentrates - minor CHO source = hindgut use of fiber Dietary VFA from hindgut ferm. of fiber protein should not be considered a good source of energy in horses

Answer 9

high energy phosphate bonds (ATP, CP)

Answer 10

- point of "onset of blood lactate accumulation" (OBLA) - point at which IM lactate production + accumulation overwhelms liver's ability to catabolize lactate → ↑ plasma [LA] typically ~ 60-80% of max effort (% HRmax + %VO2max)

Answer 11

Commonly agreed that 5-10 min post-exercise = peak plasma [LA] for most exercise bouts - ↑ active warm-down → ↓ IM + plasma [LA] post-exercise [LA] can be used to assess: - innate ability - severity of exercise bout - fitness - response to training (should ↓ with ↑ fitness)

Answer 12

Peripheral Fatigue: - ↑ [LA] - ↓ substrate availability (↓ blood + muscle GLC or FFA) Central Fatigue: - ↓ blood + brain GLC - ↑ blood + brain NH3 - ↑ blood + brain tryptophan

Answer 13

LA productin allows anaerobic exercise to continue longer than if not produced ↑ [LA] → altered Ca2+ activity @ muscular SR - ↓ myofibrillar contractility - ↑ muscular fatigue ## Footnote glucose infusions can help delay onset of fatigue

Answer 14

- perfusion of CNS = hydration, BP, oxygenation - A-B/electrolyte balance - thermoregulation - energy balance (blood glucose) - neurotoxins from exercise - peripheral v central fatigue

Answer 15

↑ blood [NH3] associated with intracranial neuro signs in horses w/ hepatoencephalopathy - possible central mediator of fatigue - tested infusions = no treatment effect on time to fatigue another proposed mediator = tryptophan - used ilegally in USA show hunters to calm them down for horse shows - tryptophan overrides glucose

Answer 16

- supp. fuel for energy production - affect flux of fuels in energy pathways - delay or minimize affects of end-product accumulation (heat,lactate) - affect NS by affecting coordination, recruitment of muscle fibers or psychological effects

Answer 17

- dietary manipulations - B vitamins - antioxidants - hemantinics - alkalinizers

Answer 18

Type of feed before exercise: - ↑ CHO - ↑ fat - ↑ sugar beet pulp (SBP) - ↑ protein Debate: composition of meal - forage v grain - amount of forage - timing of forage

Answer 19

Forage: - meals consumend 2-3 hrs pre-exercise have minimal effects on substrate availabilty + oxidation during sustained exercise - hay ad libitum for 12-24 hrs pre-exercise may ↑ gut fill → ↑ BW → ↓ performance Grain: - corn, oats, or mix **- feed < 3hrs prior to exercise** - at onset of exercise → ↑ blood [GLC + insulin] + ↓ plasma [NEFA] - during initial exercise → ↓ blood [GLC] (glycemic effect)

Answer 20

↑ muscle glycogen content no demonstrable positive effect on performance ↑ HR + ↑ blood LA accumulation in high intensity exercise ** danger of CHO overload = laminitis**

Answer 21

- inclusion of vegetbale oil fat common in diets for athletic horses - up to 20% total daily DE may be fed as fat - several weeks necessary for fat adaptation -may commercial diets now ↑ fat & ↓ CHO ↑ plasma phospholipids + cholesterol ↓ plasma triglycerides ↑muscle activity of lipoprotein lipase + b-oxidation enzymes - adult horses eventually tolerate 1 cup corn oil 2x daily top-dressed on regular grain ration - fat spoils easily in summertime if ration not fully consumed

Answer 22

Non-starch high-CHO feeds have become common additive for atheletes - ↑ fiber intake in concentrate diet = SBP or soya hulls - ↓ glycemic + insulinemic responses to concetrate meal molasses SBP → no change in responses

Answer 23

protein is an unimportant substrate during exercise dietary protein > 2g/kg b wt in endurance adverse effects on: - water intake - urea metabolism - ammonia metabolism - ↑ urinary N* ## Footnote *adverse effects on resp health d/t ↑ ammonia content of urine in stalls

Answer 24

most equine diets contain sufficient B vitamin conc. except B12 since its gut-synthesized B1 = thiamine - coenzyme in coversion of pyruvate to acetylCoA - given in high enough doses, it would lower blood [LA] -

Answer 25

produced from dietary precursors commerical carnitine supplements produced/marketed for horses - poorly absorbed from equine GI tract **- no measurable ↑ in muscle/plasma [carnitine]**

Answer 26

protect tissues from oxidant damage - oxidants produced at ↑ rate duringe exercise ex) vit. E, C, B-carotene, coenzyme Q10 above-optimal levels not ergogenic

Answer 27

deficiency not common in horses - degenerative myelopathy - equine LMN disease (LMND) deficiency → ↓ time to fatigue in horses negative correlation between plasma [antioxidants] & [CK/AST] after endurance exercises

Answer 28

"blood-builders" widely used in horse industry limited research to support use spleen = huge red cell reserve for horse examples involved in Hb/RBC synthesis: - iron, copper, zin - B6, B12, folic acid iron deficiency does not occur in horses under normal NRC feeding conditions normal horses' red cell parameters do not respond to hematinics

Answer 29

exercise of sufficient intensity results in accumulation of lactic acid → acidosis may adversely affect contractile properties of exercising muscle oral bicarb supp. produces metabolic alkalosis which may help to buffer lactic acidosis & allow continued intense exercise **illegal under nearly all racing rules (test close to race time)** manipulate race outcome by: - improving performance when used - adversely affecting performance when withdrawn **furosemide ↑ plasma bicarb** oral sodium acetate produced metabolic alkalosis similar to that produced by sodium bicard but with later peaks in pH, pCO2, tCO2, HCO3- + BE

Answer 30

distribution based primarily on myosin ATPase staining activity (depends on pH of stain) - Type I = endurance fibers - Type II = sprinting fibers

Answer 31

endurance "red" ↑ myosin ATPase activity after acid-preincubation ↓ in area (not as powerful) ↑ aerobic capacity (endurance) - ↑ TCA cycle activity - ↑ mitochondrial enzyme activites → ↑ oxidative phosphorylation

Answer 32

sprinting "white" ↓ myosin ATPase activity after acid pre-incubation ↑ in area (more powerful) ↓ aerobic capacity

Answer 33

- can't convert between types I + II - can improve oxidative characteristics of Type II fibers w/ endurance training - training can result in measurable ↑ in oxidative enzymes characteristic of endurance/aerobic fitness

Answer 34

myokine protein normally responsible for inhibition of myogenesis = musce cell growth + differentiation animals lacking myostatin have more mucle mass those with mutations in both copies of gene = signifcantly more muscle mass Absence: - double-muscled cattle = belgian blue, piedmontese - whippets - TB "speed gene"

Answer 35

change fiber type distribution ← ↑ oxidative fiber types ↑ muscle enzyme conc. → - ↑ muscle oxi. capacity - ↑ muslce aerobic enzyme conc. - NC in muscle anaerobic enzyme conc. - ↑ fat catabolism for energy source ↑ muscle glycogen conc. ↑ muscle fiber hypertrophy ↑ muscle capillary density ↑ muscle capillary transit time ↑ a-v O2 difference ↑ myoglobin conc. → ↑ O2 transport ↑ NM coordination/motor skill

Answer 36

bone remodels according to stress/loads placed upon it normal bone requires certain daily loads/stresses to maintain normal homeostasis strain = derformation as result of load stress = force applied/cross sectional area exercise stresses/loads: - training/conditioning excercises - velocity of training + performing - event specific strains/loads + stresses

Answer 37

- exercise induces remodeling of bone - changes take weeks-months - less malleable than CV or muscular responses to exercise - failure in bone adaptation can result in injury or failure or bone +/- soft tissue Assessment: - radiography - scintigraphy - U/S velocity - markers of bone metabolism - CT, MRI, PET - etc.

Answer 38

- areas of ↑ bone activity have ↑ uptake of phosphorus/phosphate - uptake of radiolabeled MDP is also ↑ in areas of ↑ bone activity - after administration of MDP, gamma camera detects ↑ gamma emmission from areas of ↑ bone activity

Answer 39

- asymptomatic appropriate changes in bone - asymptomatic inappropriate changes in bone - diffcult to diagnose - symptomatic inappropriate changes in bone

Answer 40

period of time after training/conditioning program has been discontinued undergoing stepwise treadmill exercise test after 5 weeks of rest - previously fit SB horses had no measurable changes in: - VO2max - Q - blood gas tensions - pH - plasma [LA] - less rapid ↓ in aerobic capacity than humans - minimal ↓ in agility flexibility, skill, NM coordination - NC in muscle strenght (anaerobic capacity) - sprinters especially can maintain fitness during brief periods of enforced rest

Answer 41

- all atheltic horses + sprinters can benefit from ↑ CV fitness - long slow trotting work → ↑ CV fitness - only trains horse to go slowly - eventually speed workouts must be introduced for sprinters response specific to sprint training: - NC in muscle anaerobic enzyme conc. - ↑ muscle hypertrophy - ↑ NM coordination - ↑ muscle capillary destiny - ↑ mnuscle capillary transit time - ↑ a-v O2 difference - ↑ myoglobin conc. → ↑ O2 transport

Answer 42

- adopted in humans - effective means of training SB racehorses - commonly do 2-3 sprinting exercises with considerable jogging between bouts - ~ fewer reps than humans 5 wks of combined interval + endurance training → metabolic adaptations comparable to those seen with 12 mo of conventional SB race training most agree: - not a panacea - harder on horses' legs + minds - requires more attention + time + patience

Answer 43

- event horses + endurance horses must compete over varied terrain - trail riding for fitness training inevitably leads to terrain changes - commonly used in England for TB racehorse training

Answer 44

true sprinters training (sprinting) → - ↑ muscular strenght → ↑ power - ↑ CV conditioning

Answer 45

- dressage + para-dressage - driving + para-driving - jumping - eventing - vaulting - endurance

Answer 46

- dressage - jumping - eventing (3 days) = dressage + cross country + jumping tests

Answer 47

each horse in class performs same test test designed to elicit horse + rider pair's ability + preparadness to demonstrate: - willingness/behavior - movement/gait - balance - suppleness welfare issue in europe regarding poll hyperflexion - can lead to dorsal pharyngeal collapse when on bit - repeatable DDSP + coughing may occur

Answer 48

"western seat dressage" all competitors ride a single published pattern ground jury members score the ride high score wins prone to hind limb injuries d/t sliding stops: - stifle - hock - high suspensory might wear special shoes

Answer 49

Hunters: - judged by manners, freedom of movement + gait, temperament Jumpers: - not judged - scored on ability to clear jumps without knockdowns within time allowed

Answer 50

Long Format (Classic) - Day 1 = dressage test - Day 2 = cross country (4 phases) - Day 3 = jumping test Short Format - only phase D - cross country of cross country test - seperate team + individual competitions - need seperate horses for one trainer

Answer 51

rectal temp may increase to ~107F inital HR ~180-200/min initial RR ~180/min indicators of a need for ↑ cooling efforts: - T ↑ while recovering - inversion of HR + RR while recovering aggressive cooling may be required

Answer 52

when jumping over hurdles horses prone to injure shoulder, neck or head rider prone to injury different hurdles made to help prevent injury - frangible pins = has soft spot that break upon contact - MIMs chlips = keeps pole from falling + rolling away

Answer 53

retain "long format" - Phase A = trotting - Phase D = walking to recover from A - Phase E = obstacles

Answer 54

races = 25-100 miles < 24 hrs arabians most successful - ↑ type I fibers - ↑ plasma [FFA] - ↓ RER ## Footnote lose ~5% of BW in 100 miles → takes ~48hrs to put weight back on

Answer 55

- distance event similar to endurance racing - distance = 12-100 miles - shorter segments split 1-3 days Ride is judged, not based on fastest finisher: - fitness : HR recovery - soundess/way of going - horses' trail manners/behavior

Answer 56

~1400-2200 lbs true weight-lifters large muscles masses → - ↑ power for pulling loads - ↓ endurance for long trips - poor innate CV abilities - thermoregulation is more difficult smaller heart + spleen size relative to size compared to other breeds

Answer 57

Racing: - international = by ind. country - canada = provincial - USA = by individual states Non-racing - FEI - Equine canada - USEF (USA)

Answer 58

1) Zero Tolerance = FEI 2) allowable limits 3) performance day use allowed (have thresholds)

Answer 59

- To win = stimulant, ergogenics - To lose = depressants - to restore "normal performance" = NSAIDS, intra-articular corticosteroids - to mask/dilute = diuretics

Answer 60

- stimulants = opioids, cocaine, amphetamines - ergogenics = bicarb + other alkalinizers - blood-doping = EPO - anabolics = anabolic steroids, GH, B adrenergic agonists

Answer 61

- primarily a problem in racing jurisdictions - cocain + opioids - suspected in horses with quick improvement of racing form - non-racing horses which must be fast/animated = barrel racing + gaited horses - tail (ginger) - visual - auditory

Answer 62

difficult to prove given drug enahnces performance but still used/prohibited - stimulants - ergogenics = bicard, alkalinizing agents - anabolic steroids = testosterone, etc. - clenbuterol - bronchodilator, anabolic effects (prohibited in food animals)

Answer 63

- sedatives = a2 adrenergic agonists (xylazine) - tranquilizers = acepromazine, reserpine - CV depressants = b-blockers - withold water for several hours (drawing) then letting them drink ecessively before racing

Answer 64

For: - makes racehorse fail to race fast - non-racing quiet performance How? - tranquilizers - cocaine night before → excessive fatigue next day → quiet performance

Answer 65

- bronchodilators - NSAIDS - corticosteroids

Answer 66

- vaccines, anthelminthics - feed additives = vitamins, minerals

Answer 67

- opioids = prohibited under all rules - NSAIDS = rules vary widely for use during competition

Answer 68

diuretics - enhance urine production - furosemide not as critical in horses when relying on blood/plasma test as opposed to urine tests only

Answer 69

1. No accepted therapeutic value 2. therapeutics + high abuse potential 3. therapeutics + lower abuse potential 4. therapeutics + lowest abuse potential 5. misc. therapeutics with no abuse potential but conc. limits

Answer 70

Zero Tolerance: - for many meds especially analgesics on performance day - all NSAIDS prohibited since '92 Allowed Substances (2012) - most abx - anthelminthics - vitamins - fluids + electrolytes - anti-ulcer meds positives in the 90s mostly d/t show jumpers

Answer 71

- stimulants - depressants - performance enhancers - analgesics - masking agents prohitied NSAID used in 2011 - may not use more than 1 NSAID at any time in comp - plasma restrictions set in place Positives - NSAIDs > allowable limits - tranquilizers = short v long acting

Answer 72

FEI has zero tolerance for detection of drugs during performance EC + USEF allows one NSAID during performance