Increased Body Temperature and Heat Stroke in Dogs
Hyperthermia is an elevation in body temperature that is above the generally accepted normal range. Although normal values for dogs vary slightly, it usually is accepted that body temperatures above 103° F (39° C) are abnormal.
Heat stroke, meanwhile, is a form of non-fever hyperthermia that occurs when heat-dissipating mechanisms of the body cannot accommodate excessive external heat. Typically associated with temperature of of 106° F (41° C) or higher without signs of inflammation, a heat stroke can lead to multiple organ dysfunction.
This condition can lead to multiple organ dysfunction. Temperatures are suggestive of non-fever hyperthermia. Another type, malignant hyperthermia, is an uncommon familial non-fever hyperthermia that can occur secondary to some anesthetic agents.
Hyperthermia can be categorized as either fever or non-fever hyperthermias. Fever hyperthermia results from inflammation in the body (such as the type that occurs secondary to a bacterial infection). Non-fever hyperthermia results from all other causes of increased body temperature.
Other causes of non-fever hyperthermia include excessive exercise, excessive levels of thyroid hormones in the body, and lesions in the hypothalamus, the part of the brain that regulates body temperature.
Non-fever hyperthermia occurs most commonly in dogs (as opposed to cats). It can affect any breed, but is more frequent in long-haired dogs and short-nosed, flat-faced dogs, also known as brachycephalic breeds. It can occur at any age but tends to affect young dogs more than old dogs.
Symptoms and Types
Hyperthermia can be categorized as either fever or non-fever hyperthermias; heat stroke is a common form of the latter. Symptoms of both types include:
- Excessive drooling (ptyalism)
- Increased body temperature - above 103° F (39° C)
- Reddened gums and moist tissues of the body
- Production of only small amounts of urine or no urine
- Sudden (acute) kidney failure
- Rapid heart rate
- Irregular heart beats
- Stoppage of the heart and breathing (cardiopulmonary arrest)
- Fluid build-up in the lungs; sudden breathing distress (tachypnea)
- Blood-clotting disorder(s)
- Vomiting blood (hematemesis)
- Passage of blood in the bowel movement or stool
- Black, tarry stools
- Small, pinpoint areas of bleeding
- Generalized (systemic) inflammatory response syndrome
- Disease characterized by the breakdown of red-muscle tissue
- Death of liver cells
- Changes in mental status
- Muscle tremors
- Wobbly, incoordinated or drunken gait or movement (ataxia)
- Unconsciousness in which the dog cannot be stimulated to be awakened
- Excessive environmental heat and humidity (may be due to weather conditions, such as a hot day, or to being enclosed in an unventilated room, car, or grooming dryer cage)
- Upper airway disease that inhibits breathing; the upper airway (also known as the upper respiratory tract) includes the nose, nasal passages, throat (pharynx), and windpipe (trachea)
- Underlying disease that increases likelihood of developing hyperthermia, such as paralysis of the voice box or larynx; heart and/or blood vessel disease; nervous system and/or muscular disease; previous history of heat-related disease
- Poisoning; some poisonous compounds, such as strychnine and slug and snail bait, can lead to seizures, which can cause an abnormal increase in body temperature
- Anesthesia complications
- Excessive exercise
- Previous history of heat-related disease
- Age extremes (very young, very old)
- Heat intolerance due to poor acclimatization to the environment (such as a heavy coated dog in a hot geographical location)
- Poor heart/lung conditioning
- Underlying heart/lung disease
- Increased levels of thyroid hormone (hyperthyroidism)
- Short-nosed, flat-faced (brachycephalic) breeds
- Thick hair coat
- Dehydration, insufficient water intake, restricted access to water
The act of urinating on objects or areas as a method of marking territory
A cavity in the mouth where the respiratory systems and gastrointestinal systems come together
The voice box; this is one part of the respiratory system
Something that is related to the whole body and not just one particular part or organ
Something that becomes worse or life threatening as it spreads
The term for a quick heartbeat
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
upper respiratory tract
The section of the respiratory system that contains the mouth, nose, pharynx, larynx, trachea, and epiglottis.
The windpipe; it carries air from the bronchi to the mouth
Part of the thalamus that helps to regulate the release of certain hormones
High body temperature
A medical condition in which an animal is unable to control the movements of their muscles; may result in collapse or stumbling.
Any substance known to eliminate feeling; usually applied during a painful medical procedure.
Term used to imply that a situation or condition is more severe than usual; also used to refer to a disease having run a short course or come on suddenly.
An animal with a wide head, short in stature.
A record of the activity of the myocardium
The act of throwing up blood
The area between the abdomen and thighs; the inguinal area
The term used to describe the movement of an animal
The act of helping an animal to adjust to something or some place foreign to them.