{"id":7499,"date":"2025-05-28T17:46:18","date_gmt":"2025-05-28T17:46:18","guid":{"rendered":"https:\/\/www.ambiotecsolutions.com\/?p=7499"},"modified":"2025-05-28T18:39:39","modified_gmt":"2025-05-28T18:39:39","slug":"estres-termico-en-porcino-estres-por-calor-en-cerdos-y-sus-soluciones","status":"publish","type":"post","link":"https:\/\/www.ambiotecsolutions.com\/en\/estres-termico-en-porcino-estres-por-calor-en-cerdos-y-sus-soluciones\/","title":{"rendered":"Heat stress in swine: heat stress in pigs and its solutions."},"content":{"rendered":"
\n

Heat Stress<\/h1>\n

Heat stress<\/strong> in swine is a physiological disruption that occurs when the ambient
temperature and relative humidity exceed the optimal range or &quot;thermoneutral zone&quot; for
these animals, which is between 16\u00b0C and 22\u00b0C for adults. When the ambient
temperature exceeds this range, the pig faces difficulties in regulating its body
temperature due to its anatomical and physiological limitations: few functional sweat
glands and a thick layer of subcutaneous fat that makes it difficult to dissipate heat.
Under normal conditions, thermoregulation mechanisms include heat transfer to the
skin (vasodilation), increased respiratory rate (panting) to promote water evaporation
through the airways, reduced physical activity and food consumption, and seeking cool
or moist areas.<\/p>\n

However, as the ambient temperature and\/or humidity increase, these mechanisms
become insufficient to maintain internal thermal balance. The excess heat accumulated
cannot be effectively eliminated, and an imbalance occurs between body heat<\/strong>
production (heat generated by metabolism and activity) and heat loss to the<\/strong>
environment<\/strong>, leading to an increase in core body temperature. If this state persists, the
animal enters a state of stress, characterized by symptoms such as intense panting,
lethargy, skin redness, decreased appetite, behavioral changes, and even more severe
disorders such as incoordination, collapse, or, in extreme cases, death.
Heat stress in swine not only affects their welfare but also generates negative
consequences at the productive level (lower weight gain, lower fertility and viability of
litters, poorer carcass quality), immune and health level (increased susceptibility to
diseases). Therefore, environmental management and adaptation of facilities are
essential to prevent and reduce the impact of this condition on pig farms.<\/p>\n<\/div>\n

Thermoregulation Mechanisms<\/h2>\n
\n

1. Increased Respiratory Rate (Panting)<\/h3>\n

Panting is the main physiological resource used by pigs to dissipate heat. By
increasing the respiratory rate, pigs cause greater water evaporation from the mucous
surfaces of the upper airways, mainly at the level of the pharynx and trachea. This
mechanism allows a part of the pigs&#39; body heat to be released into the environment
thanks to the evaporation process, which is an endothermic phenomenon (absorbs
thermal energy). During heat episodes, the respiratory rate can multiply several times
compared to the usual values, reaching in extreme cases more than 100 breaths per
minute.<\/p>\n

However, panting has important limitations since the ability to evaporate water depends
heavily on environmental humidity: when it is high, the efficiency of the process
decreases drastically. Prolonged panting can cause respiratory alkalosis (by eliminating
too much CO\u2082) and quickly dehydrate the animal, worsening the situation. In addition,
it is a mechanism that involves a large additional energy expenditure.<\/p>\n

2. Reduction of Physical Activity and Food Consumption<\/h3>\n<\/div>\n
Another characteristic response to heat is the decrease in both physical activity and
food intake. By moving less, pigs limit the heat generation derived from muscle
contraction and other metabolic processes associated with exercise. Similarly, by
reducing the amount of food ingested, the &quot;heat of fermentation&quot; produced during digestion decreases, especially relevant with diets rich in fiber or crude protein, since digestion and metabolism generate additional heat as a byproduct.<\/p>\n

This strategy, although effective in minimizing endogenous heat production, carries
risks such as lower energy and essential nutrient consumption, affecting growth, pork
milk production, or reproductive rate depending on the production phase. If the
reduction in consumption is prolonged, productive recovery can be slow even when
temperatures decrease.<\/p>\n

3. Seeking Cool or Moist Areas<\/h3>\n

It is common to observe them seeking areas of the pen in the shade, near cool walls,
downwind from air currents, or wallowing in mud or puddles of water if available. Direct
contact with colder surfaces facilitates heat loss from their own body by conduction
(from the body to the ground or to water\/mud).
In the case of mud or water, in addition to conduction, evaporation is added: the water
that remains on the skin and evaporates extracts body heat, helping to lower the
animal&#39;s core temperature. This natural behavior has been fundamental for the survival of pigs in the wild, but in intensive systems where these options are not offered, the effectiveness of this mechanism is greatly reduced.<\/p>\n

4. Peripheral Vasodilation<\/h3>\n

At the physiological level, another key response is the vasodilation of cutaneous blood
vessels. During heat situations, the autonomic nervous system activates mechanisms
by which the blood vessels of the skin dilate, facilitating a greater blood flow to the
body surface. As a result, the heat transported by the blood from the internal organs is
transferred more efficiently to the skin, and from there to the environment by
convection and radiation<\/strong>.
This explains the visible redness in the skin and ears of pigs subjected to intense heat:
it is fluid blood in the superficial capillary beds. However, if the ambient temperature
gets too close to the body temperature, the heat transfer becomes inefficient, and this
mechanism is no longer sufficient by itself to prevent overheating.<\/p>\n

Key Limitations of Mechanisms in Swine<\/h2>\n

The porcine species stands out, unlike other species, for its limited sweating capacity.
The sweat glands in these animals are very poorly functional, and their skin is thick,
which practically cancels the classic sweating mechanism that animals such as bovines
or equines do possess. In addition, breeds selected for production often have
considerable subcutaneous fat layers, which further limits heat transfer to the body
surface.
For these reasons, panting and seeking moist\/cool contact become the priority, albeit
inefficient, resources for heat dissipation, especially in unfavorable environmental
conditions such as high temperatures or high humidity.
Thus, collapse occurs when the ambient temperature (and\/or relative humidity)
exceeds the pig`s ability to dissipate excess heat through the aforementioned
mechanisms (panting, vasodilation, etc.). The thermoneutral zone for pigs varies
according to age and weight, but in adults it is usually between 16 \u00b0C and 22 \u00b0C<\/strong>. When
the ambient temperature exceeds 26\u201328 \u00b0C<\/strong>, the first effects of heat stress may appear,
and from 32\u201334 \u00b0C<\/strong> (especially with high humidity), the situation becomes critical and
the risk of collapse increases. The risk of collapse is even greater in heavy animals,
pregnant or lactating sows, and animals with little ability to move to cool areas.<\/p>\n

\"Mecanismos<\/p>\n

\n

Initial and Progressive Signs of Heat Stress<\/h2>\n

1. Early Changes (before collapse):<\/h3>\n

Increased respiratory rate (evident panting), decreased feed and water consumption,
restlessness, prostration or seeking cool, moist or more ventilated areas, isolation from
other animals and reduced activity, moist skin as a result of panting, possible excessive
salivation and\/or reddening of the skin and ears due to peripheral vasodilation.<\/p>\n

2. Signs of Worsening Due to Heat Stress:<\/h3>\n

Rapid and shallow breathing (sometimes &gt;100 breaths\/minute), lethargy or
exaggerated weakness, muscle tremors or incoordination of movements, tendency to
lie laterally and stretch the limbs (to increase the heat dissipation surface) and\/or
increased body temperature (often >40 \u00b0C)<\/p>\n

3. Collapse and Systemic Failure:<\/h3>\n

The effects of high and persistent heat stress over time result in prostrate animals,
unable to get up, convulsions or disorientation, cyanosis of the mucous membranes
(sign of hypoxia), weak or irregular pulse, difficulty breathing and\/or sudden death due
to multiorgan failure, severe hyperthermia or heart failure.
Collapse due to heat stress is a veterinary emergency. If no action is taken quickly to
reduce the animal&#39;s body temperature and improve the environment, mortality can be high. Furthermore, even if they survive, organ damage (especially renal and cardiac)
and productivity losses are usually very serious.<\/p>\n

\n

Heat Stress Conditions According to Production Stage<\/h2>\n

On the other hand, the impact of heat stress is different depending on their production
stage, due to their physiology, metabolism and particular requirements in each phase:<\/p>\n

1. Suckling Piglets<\/h3>\n

Very young piglets are more vulnerable to cold than to heat, but during prolonged heat
waves they can quickly suffer dehydration due to their high proportion of body water
and limited thermoregulation capacity.
They tend to lose weight, lethargy occurs, and there is an increase in mortality,
especially if the sow reduces milk production due to being affected by heat. In addition,
if the sow reduces breastfeeding time or suffers low milk production, the piglets may
present hypoglycemia and poorer growth.<\/p>\n

2. Pregnant Sows<\/h3>\n

They are extremely sensitive to heat, especially in the last third of gestation. Heat
stress reduces food intake, which can lead to lower fetal development (low birth weight
piglets), increased embryonic mortality and abortions and premature delivery or
reproductive difficulties. In the long term, there may be fewer piglets weaned and
poorer reproductive performance in subsequent cycles.<\/p>\n

3. Lactating Sows<\/h3>\n

High temperatures markedly reduce voluntary feed consumption, which triggers lower
milk production, loss of body weight, increased risk of post-weaning reproductive
failure, and affects the growth and survival of piglets. On the other hand, the ” sow prostrate from heat”; syndrome can be observed, where the sow literally does not eat or
breastfeed correctly due to thermal exhaustion.<\/p>\n

<\/p>\n

4. Transition and Fattening Animals<\/h3>\n

Fattening pigs are fast-growing animals, with high metabolisms and, therefore, high
endogenous heat production. The effects of heat can lead to a significant decrease in
feed consumption (in some cases up to 30% less), poorer feed conversion and lower
growth rate, increased morbidity (more digestive, respiratory problems, etc.), greater
risk of mortality in heavy animals or with high density and loss of carcass quality
(greater fat thickness, less lean). In advanced fattening phases, the risk of “heat stroke”; or sudden death is greater due to their body volume and lower capacity to dissipate
heat.<\/p>\n

5. Reproductive Males<\/h3>\n

Heat deteriorates seminal quality (low sperm motility and viability, teratozoospermia),
which reduces fertility. The effects can appear weeks after the heat wave due to the
sperm production cycle.<\/div>\n

<\/p>\n

\u00a0<\/h2>\n

Impact of Heat Stress<\/h2>\n
\n

1. Economic Repercussions on Pig Farms<\/h3>\n