Thermoregulation

Question 1

The thermoregulatory centre is located where in the brain

Answer 1

The hypothalamus

Question 2

Heating mechanisms

Answer 2

Basal metabolic rate
Absorption from surrounding
Heat retention mechanisms

Question 3

3 ways heat is absorbed from the environment

Answer 3

Conduction: direct contact

Convection: heat transfer from body to surrounding air

Radiation: absorption from infra-red energy

Question 4

Heating retention mechanisms

Answer 4

Piloerection

Vasoconstriction

Behaviour responses (herding)

Shivering

Question 5

Cooling mechanisms

Answer 5

Decrease metabolic rate

Heat in deep tissues is transferred to skin via blood flow

Evaporation

Vasodilation

Behaviour response (shade, decreased activity)

Question 6

Normal body temp of cats and dogs

Answer 6

38.5 +/- 0.5 degrees Celsius

Question 7

Normal body temp of cattle

Answer 7

38.5 +/- 0.5 degrees Celsius

Question 8

Normal body temp of horses

Answer 8

38 +/- 0.5 degrees Celsius

Question 9

True or false

Pain and extreme stress can cause a mild increase in temperature

Answer 9

True

Question 10

Dangerous temperatures for all species

Answer 10

Hot: 43 degrees Celsius and above (rapidly dying)

Cold: 23 degrees Celsius (dying)

Question 11

Fever (Pyrexia)

AKA physiological hyperthermia

Answer 11

Purposeful increase in body temp in response to something abnormal occurring in the body

Question 12

Why is a fever a normal part of the body’s immune response

Answer 12

Higher temps inhibit virus and bacteria from replicating by denaturing viral and bacterial proteins

Question 13

Why is treatment of true fever not always recommended

Answer 13

To allow the body’s natural immune response to do its job

Question 14

True or false
Treating a fever is only indicated if the temperature is high enough or sustained long enough to pose a risk to the patients proteins

Answer 14

True

Question 15

Proteins in the cells start to become damaged at

Answer 15

42 degrees Celsius

And irreversible damage occurs at 43 degrees Celsius

Question 16

Treatment options for fever

Answer 16

Treat underlying problem

Non-steroidal anti-inflammatories

Passive cooling

Question 17

Pathological hyperthermia occurs when

Answer 17

There is excessive heat generation or the body cannot cool off fast enough

AKA

The increase in temperature is not supposed to be happening and it’s causing damage

Question 18

Intrinsic risk factors for hyperthermia

Answer 18

Obesity
Hair coat
Dehydration
Underlying issues 
Brachycephalic dogs (respiratory issues)
Genetic predisposition to drug reactions 
Exercise

Question 19

Extrinsic risk factors for hyperthermia

Answer 19

Environmental temp approaches body temp
>80% humidity (decreases evaporation)
Over crowding/poor ventilation/transport/ capture stress
Water deprivation

Question 20

Heat stress

Mild hyperthermia=heat exhaustion

Answer 20

Often subclinical
Signs include: lethargy, sweating, panting, decreased performance, decreased production, changes in hydration

39.1-41.5 degrees Celsius

Question 21

Treatment of heat stress

Answer 21

Passive cooling (shade, ventilation, decrease ambient temps, fans, misting, water)

Prognosis is good if it does not progress

Question 22

Heat stroke

Severe hyperthermia

Answer 22

Core body temp exceeds 41.5 degrees Celsius for a long period of time

Anything above 43 degrees Celsius is critical

Question 23

disseminated intravascular coagulation

Answer 23

DIC= DEATH IS COMING

Question 24

Goal when treating heat stroke

Answer 24

To decrease to 39.5 degrees within 30-45 minutes and stop there

Question 25

Passive surface cooling

Answer 25

``` Cool room Shade Fans/ventilation Soak with tepid water Drink fluids ```

Question 26

Active surface cooling (if <43 degrees)

Answer 26

Apply cold packs to neck, foot pads, inguinal regions and axilla (where major blood vessels are) Goal is to cool blood as it moves through the largest vessels

Question 27

Active core cooling -for critical heat stroke

Answer 27

Chilled IV fluids Cool water enemas

Question 28

Why should you not immerse a heat stroke patient into an ice bath?

Answer 28

It will cause vasoconstriction and shivering: things that will create more heat

Question 29

Mu-agonist induced hyperthermia in cats

Answer 29

A class of opioids that can cause hyperthermia in cats

Question 30

Signs of mu-agonist hyperthermia

Answer 30

Temp does not drop as expected during anesthesia Gradual increase in temp

Question 31

Treatment of mu-agonist hyperthermia

Answer 31

Intervene at 41 degrees Treat by reversing the opioid

Question 32

What is the most common reason patients will die from mu-agonist hyperthermia?

Answer 32

Because it is not caught early enough

Question 33

Malignant hyperthermia

Answer 33

Fatal hyperthermia caused by exposure to inhalant anesthetics Most common in pigs Inherited defect in skeletal muscles metabolism triggered by exposure: causes excessive release of calcium causes prolonged muscle contraction

Question 34

Hypothermia due to increased heat loss

Answer 34

Heat production is normal ``` Related to environmental conditions Cold temps Vet Low BCS neonates born in snow Small animals ```

Question 35

Hypothermia due to lack of heat production

Answer 35

Can occur with severe illness or shock Brain trauma Adverse effect of anesthesia

Question 36

Mild hypothermia

Answer 36

34-37 degrees Celsius Signs: Lethargy, depression, shivering, loss of suckle reflex in young

Question 37

Moderate hypothermia

Answer 37

28 to 33 degrees Celsius (loose physiological warming responses at 33 degrees) Signs: altered LOC, decreased metabolism, loss of thermoregulation, decreased HR and cardiac output, decreased muscle function,

Question 38

Severe hypothermia

Answer 38

<28 degrees Celsius Signs: loss of consciousness, coma, death, organ dysfunction, DIC, CNS shut down

Question 39

Prevention for hypothermia

Answer 39

Proper shelter Avoid wetness in cold temps Minimize anesthesia times, warm IV fluids, monitor temps

Question 40

Treatment for hypothermia

Answer 40

Passive surface methods Support vital functions Active warming methods if needed Stop warming at 37 degrees

Question 41

Why do we want to stop warming a hypothermia patient at 37 degrees Celsius

Answer 41

So they don’t get hot and start to thermoregulate to cool themselves down (sweating, panting etc)

Question 42

Passive surface warming methods

Answer 42

Get dry Get out of cold area Blankets Foil wrap

Question 43

Active surface warming methods

Answer 43

Mild heat to surface, which transfers to core Warm packs on axilla, inguinal, neck, etc

Question 44

Active core warming methods

Answer 44

Breathe in warm air Warm IV fluids Warm enema Monitor temp every 15 minutes

Question 45

After drop phenomenon

Answer 45

Occurs when the patient reaches 37 degrees but heat sources are not removed Patient becomes too warm at the core, to try and cool down again blood from the periphery (which is cool) will move to the core and cause a sudden drop in temp which can affect heart and CNS

Question 46

Re-warming shock

Answer 46

Occurs when there is external warming without core warming Causes vasodilation in the skin, blood moves towards the skin and away from organs so the patient goes into shock

Question 47

Frostbite

Answer 47

Frozen tissue after exposure to extremes cold

Question 48

Rick factors of frostbite

Answer 48

Cold, wet, windchill Neonates <48 hours of age Really old or sick If they have poor perfusion to the extremities

Question 49

Pathology of frostbite

Answer 49

Ice crystals and expansion of frozen water cause permanent tissue damage Lack of blood flow increases risk of necrosis Increased risk of bacterial infection upon thawing

Question 50

Necrosis

Answer 50

Dying or dead cells or tissue

Question 51

Signs of frostbite

Answer 51

Skin is hard, cold, pale, loss of sensation Sounds solid when tapped Red(not as severe) or black (extreme)

Question 52

Treatment of frostbite

Answer 52

``` Take out of cold Slow passive surface rewarming Protect damaged areas from patient (might chew on them) Support organs Anti inflammatories ```

Question 53

What should you never do with frostbite

Answer 53

Never rub Never immerse in hot water Never thaw and then refreeze