Hyperthermia and Hypothermia

Vocabulary practice flashcards covering the definitions, physiological mechanisms, clinical signs, and first aid treatments of hyperthermia and hypothermia in domestic animals.

Core Temperature

The internal body temperature of an animal.

Hyperthermia

A condition characterized by an abnormally high core body temperature resulting from an inability to regulate internal temperature or an inability to expel excess heat.

Hypothermia

A condition characterized by a sub-normal core body temperature, commonly triggered by overexposure to cold, systemic disease, anaesthesia/sedation, or severe shock.

Normal Body Temperature Range (Dog)

$38.3 - 38.7\,^\circ\text{C}$ ($100.9 - 101.7\,^\circ\text{F}$).

Normal Body Temperature Range (Cat)

$38.0 - 38.5\,^\circ\text{C}$ ($100.4 - 101.6\,^\circ\text{F}$).

Normal Body Temperature Range (Rabbit)

$37.0 - 39.4\,^\circ\text{C}$ ($99 - 103\,^\circ\text{F}$).

Pyrexia

An elevation in body temperature caused by increased internal heat production by or within the body, which is clinically distinct from hyperthermia.

Hypothalamic Failure Threshold (Hyperthermia)

A body temperature exceeding $42\,^\circ\text{C}$ ($108\,^\circ\text{F}$), at which the hypothalamus can no longer function and irreversible cellular damage occurs.

Peripheral Vasodilation (Hyperthermia Response)

The physiological dilation of peripheral blood vessels to redirect blood flow toward the extremities and skin surface to facilitate heat dissipation.

Cyanosis

A bluish-purple discoloration of the mucous membranes indicating severe hypoxemia, seen in advanced hyperthermia and respiratory collapse.

Hyperthermia Cooling Endpoints

Active cooling must be ceased when the animal's temperature is within $1\,^\circ\text{F}$ of normal; cold water immersion stops once core temperature falls below $39.4\,^\circ\text{C}$, and the animal is dried off once reaching $39\,^\circ\text{C}$ to avoid hypothermia and shock.

Peripheral Vasoconstriction (Hypothermia Response)

The physiological constriction of peripheral blood vessels to redirect and conserve warm blood for vital internal organs, which subsequently slows respiration and heart rate.

Bradycardia

An abnormally reduced or slowed heart rate, observed as a clinical sign of hypothermia.

Bradypnoea

An abnormally reduced or slowed respiratory rate, observed as a clinical sign of hypothermia.

Passive Rewarming

A hypothermia rewarming strategy that relies on drying a wet animal with towels and raising the ambient temperature of the environment.

Active Surface Rewarming

A hypothermia treatment method that applies external conductive heat sources directly to the animal's body surface, such as heat pads or hot water bottles.

Active Central Rewarming

A veterinary hypothermia treatment technique that warms the core internal organs directly using warmed intravenous fluids via a warm drip.

Rapid Rewarming Shock

A dangerous complication occurring when direct heat is applied too quickly to a hypothermic animal, causing peripheral vessels to dilate rapidly and shunting critical blood supply away from vital core organs.