The Impact of Heat Stroke on Fighting Cocks

The Impact of Heat Stroke on Fighting Cocks
By Asst. Prof. Dr. Somphoth Weerakul (DVM)

Academic Principles and Comparative Study
Let us first understand the underlying academic principles through a comparative lens. When external temperatures are extremely high and the body cannot regulate its internal temperature within a normal range, an abnormally high body temperature occurs.

In humans, various mechanisms maintain a body temperature between 36–37.5°C. However, if the body cannot combat extreme external heat, the core temperature may rise above 40°C, reaching a dangerous level. In human cases, mortality rates range from 10–50%, and 7–20% of survivors suffer permanent neurological damage. This condition is commonly known as Heat Stroke.

Heat is generated not only by the environment but also through internal metabolism. Only a portion of food metabolism is converted into usable energy; the remaining 70–80% is released as heat. During exercise, the demand for energy increases, causing the body to produce even more heat. Therefore, individuals in hot environments are at risk, and the risk intensifies with heavy physical exertion. This problem is frequently found in military personnel or athletes training outdoors. Additionally, exercise triggers the release of hormones such as epinephrine, which further stimulates heat production.

Physiological Responses to Increased Body Heat
Understanding how the body responds is as vital as acknowledging the heat itself. This allows us to consider contributing factors beyond just ambient temperature, such as the failure of cooling mechanisms. The body dissipates heat through four primary mechanisms:

Radiation: In cool air, the body radiates heat outward. This is the primary cooling mechanism, accounting for up to 60% of total heat loss. However, if the external air is hotter than the body, radiation reverses, and the body absorbs heat from the environment instead.
Evaporation: During exercise, sweating (evaporation) becomes the primary cooling mechanism. This is only effective if the atmospheric humidity is lower than the moisture on the skin. High relative humidity prevents sweat from evaporating and reduces oxygen levels in the air, leading to hypoxia and further complications.
Conduction: Heat transfer through physical contact with a cooler object. While helpful, this provides minimal cooling.
Convection: The use of air (wind) or water to carry heat away from the body.
Heat Stroke in Fighting Cocks: Causes and Risks
In fighting cocks, while high ambient temperature is a major risk, the act of fighting or training is the primary catalyst. This is known as Exertional Heat Stroke and is often linked to dehydration.

Naturally, a chicken’s body temperature is quite high, ranging from 40.6–41.7°C, which gives them some heat tolerance. However, this tolerance is not infinite; they still have a "comfort zone" similar to humans. In fighting cocks, heat stroke is closely tied to physical exertion and other health conditions, such as poor blood circulation or "thick blood" (hyperviscosity) caused by dehydration during a match.

Because chickens lack sweat glands, they cannot cool down through evaporation from the skin. They rely on radiation, but if the environment is hotter than their bodies, radiation fails. To compensate, they flap their wings (convection), seek shade, or lie on cool ground (conduction). When these fail, they rely primarily on panting (respiratory evaporation), which triggers a chain of physiological failures:

Metabolic Shifts: Initially, rapid panting expels excessive carbon dioxide while increasing oxygen intake, leading to metabolic alkalosis (the blood becomes too alkaline). However, in exercising birds, the body produces high levels of lactic acid through glycolysis, eventually shifting the state to metabolic acidosis (the blood becomes too acidic). Either extreme leads to systemic failure.
Organ Impact: These shifts cause pulmonary edema (fluid in the lungs) and ischemia (lack of blood flow) to various organs. Critical electrolyte imbalances follow, leading to sudden organ failure.
Capture Myopathy and Systemic Failure
In poultry, heat stroke rarely occurs in isolation. It is often accompanied by a condition known as Capture Myopathy, though in this context, it is caused by the trauma of fighting. High levels of lactic acid accumulate, damaging the kidneys, liver, heart, and brain.

Clinical signs include:

Neurological: Torticollis (twisted neck), ataxia (uncoordinated walking), or staggering.
Musculoskeletal: Weakness, limping, or the inability to stand.
Renal/Hepatic: White droppings (kidney issues) or bright neon green droppings (liver issues).
Vascular: Intense skin redness in the early stages, followed by extreme paleness as blood fails to reach the extremities or skin.
Digestive: Indigestion, constipation, or diarrhea, often leading to death.
Conclusion
Exertional heat stroke and muscle degeneration (myopathy) are typically interrelated, usually occurring after a history of intense fighting in hot weather. While they are distinct conditions, they are often diagnosed together based on the bird's history of exertion and environmental risk factors.