2. Thermoregulation Flashcards by Breanne More

What are the bodies heating mechanisms?

basal metab rate - determines rate of metab of nuts. and rate of skeletal muscle contraction: generates heat

How well did you know this?

Not at all

Perfectly

What are ways the body absorbs heat from the surrounding? or is generated/aquired

Absorbed:
Conduction - direct heat
Convection - heat transfer from body to surrounding
Radiation - absorption of infra-red energy
Aquired:
Piloerection
Vasoconstriction
Behavior responses (nesting)
Shivering

How well did you know this?

Not at all

Perfectly

What are the body’s cooling mechanisms?

Decrease metab rate
deep tissue heat transferred to skin
Evaporation (sweating/panting)
vasodilation
behavioral responses

How well did you know this?

Not at all

Perfectly

What are the normal temperatures for dogs, cats, cattle and equines?

K9, Fel - 38.5 +/- 0.5 degree (above 39.1 must be reported)
Cattle - 38.5 +/- 0.5
EQ - 38.0 +/- 0.5

How well did you know this?

Not at all

Perfectly

Normal ranges for hyperthermia and hypothermia (death)

43 °C and above – rapidly fatal
28 °C – dying

How well did you know this?

Not at all

Perfectly

Another name for fever

pyrexia, physiological hyperthermia

How well did you know this?

Not at all

Perfectly

What is a fever?

A purposeful increase in body temp. (>39.1) as part of inflam response
appropriate in event of infection
Heat causes denaturation of bact + viral proteins

How well did you know this?

Not at all

Perfectly

How do you treat a fever?

treat underlying problem
NSAIDS
passive cooling - fans, cool towels, fluids

How well did you know this?

Not at all

Perfectly

What is pathological hyperthermia?

when there is 1 an excessive heat generation or/and 2 cannot cool off fast enough

How well did you know this?

Not at all

Perfectly

What are intrinsic risk factors for hyperthermia?

obesity, long haircoal/wool coats/ dark fur, dehydration, underlying cv or resp disease, genetic predispotion to specific drug reactions, strenuous exercise

How well did you know this?

Not at all

Perfectly

what are extrinsic risk factors for hyperthermia

enviro temp approaches body temp (loss of convection)
>80 humidity (decreases evaporation)
over-crowding/poor ventilation/shipping and transport/capture stress
water deprivation

How well did you know this?

Not at all

Perfectly

What is heatstress?

Mild hyperthermia = heat exhaustion
39.1 - 41.5
Often sublinical. if present -
Lethargy, sweating, panting, decreased prod
inc temp inc metab demand by muscle

How well did you know this?

Not at all

Perfectly

how do you treat heat stress?

passive surface cooling - shade, proper ventilation, dec ambient temp, fants, misting, decrease density, water

How well did you know this?

Not at all

Perfectly

What is heat strok

Severe hyperthermia
Core body temp exceeds 41.5, any temp above 43 is critical

How well did you know this?

Not at all

Perfectly

What is the pathology of heat stroke

Intcell proteins denature + mitochondria stop fun - cell damage - cell death
dehydration, resp alkalosis
blood away from core to cool, lack of tissue perfussion

How well did you know this?

Not at all

Perfectly

How do you treat heat stroke?

Cool - decrease to 39.5 within 30-40 min, stop at 39.5
3 methods - passive surface cooling, active surface cooling (cold packs), active core cooling (chilled iv) (<41.5)
CV support - support blood flow to organs (<43c)
proactive/support - gi protectants, plasma transfusion (<43c)
RESTORE TEMP FROM INSIDE OUT

What is prognosis for heat stroke?

depends on how high int temp reaches, high risk of infection and sepsis, if multi-organ system or DIC(disseminated intravascular coagulation) occurs - very poor prognosis

What is Mu-Agonist Induced Hyperthermia

A class of opiods - morphine, hydromorphone, fentanyl
cats may develop hyperthermia if given, tx w/ reversal agent, fatal if not caught
intervene at 41c

What temp does irreversible protein denaturation occurs?

> 43C

What is Malignant hyperthermia

fatal hyperthermia triggered by exposure to inhalant general anesthetis (isoflurane, and sevoflurane)
in all species, rare, common in pigs
Inherited defect in skeletal muscle metal - no effect unless triggered by gas anesthetic
causes excessive Ca+ release by sarcoplasmic reticulum - contract stay contracted - muscle contract generates heat - switches to anaerobic metab - metab acidosis
temp inc 1-2 c every 5 min

What is Hypothermia?

pathological dec in body temp
due to inc heat loss or lack of heat prod

Describe how hypothermia due to inc heat loss happens

usually enviro related
wet
low BCS
neonates - heat regulation normal but less developed
Small anims - inc body surface area

describe how hypothermia due to lack of heat prod works

Secondary hypothermia
occurs with severe illness such as shock
brain trauma
consistent adverse effect of general anesthesia

Who is at the highest risk of hypothermia under general anesthesia?

<10kg, pediatrics, geriatrics, open abdominal surgery, trauma, too long a procedure, cold gasses, lackof warming

What temp is mild, moderate and severe hypothermia?

Mild - 37-34 (lethargy, shivering) moderate - 33-28 (ataxia, dec metab, loss of warming responses) severe - <28 (unconscious, coma, death

How can we prevent hypothermia?

appropriate shelter for birthing and neonatal care, avoid wetness in cold temps, minimize anesthetic times, warm IV fluids

how can we treat hypothermia?

1. maintain heat using passive surface methods 2. support vital func - o2, anti-arrhythmic drugs, warm IV fluids 3. active warming methods - warm IV fluids, start inside out STOP AT 37

What is after-drop phenomenon

Occurs if patient reaches 37 but active heating sources not removes patient too hot in core - cools down again, periphery blood moves to core, sudden core temp dec, can precipitate heart and CNS dysfunct

What is rewarming shock?

occurs if there is ext warming w/o core warming at same times sudden vasodilation in skill - blood to skin to fill blood vessel space - blood away from vital organs - shock

what is frostbite?

Frozen tissue after exposure to extreme cold

What are frost bite risk factors?

cold, wet, windchil neonates old/ill already poor perfusion of extremities

What is the pathology of frostbite?

ice crystals and expansion of frozen water cause permanent tissue damage lack of blood flow - inc risk of tissue necrosis inc risk of bacterial infection due to thawing of protective skin layer lack of movement of immune cells into area

What bact like to colonize necrotic tissue?

clostridia

What are the clinical signs of frostbite

skin is hard, cold, pale, loss of sensation/pain solid sound, knocking, when tapped

how do you treat frostbite?

take out of cold slow passive surface rewarming (never rub, move little, never in hot water) protect damaged area support core organs anti inflams, pain, antibiotics NEVER thaw and refreeze, better to leave frozenw

What is the prognosis for frostbite

only know after tissue thaws - will be red, swolen, painful damage too severe, tissue necrosis, will turn purple/black with red margins, start to slough, very high risk of bact infection (gangrene) may regain fun or amputation