# Sow Cooling Systems in Farrowing Houses ## Key Takeaways - Sows experience heat stress at effective temperatures above 70-75°F, necessitating cooling interventions as lactating sows generate significant metabolic heat and have limited thermoregulatory mechanisms beyond panting. - Drip cooling, applying 0.5-1 gallon/sow/hour to the neck and shoulders, is a cost-effective method that enhances evaporative heat loss from the skin, with optimal effectiveness when combined with air movement. - Snout cooling, delivering high-velocity air (400-600 ft/min) directly to the sow's face, is the most effective individual cooling method, leveraging the snout's vascularity and functional sweat glands for convective and evaporative heat exchange. - Evaporative cooling pads are most effective in dry climates (relative humidity <50%), reducing incoming air temperature by 10-20°F through water evaporation, but their efficacy diminishes significantly in humid conditions. - Critical monitoring indicators for heat stress include elevated sow respiration rates (>60-80 breaths/min), reduced feed intake, and monitoring room temperature at sow level (12-18 inches above floor), not thermostat height. - System failures commonly stem from clogged nozzles, misdirected airflow, or improperly located thermostats, highlighting the importance of regular maintenance and correct installation. --- Heat stress is one of the most costly and overlooked problems in swine production, and it hits hardest in the farrowing house where sows already carry a heavy metabolic load from lactation. This guide covers the full range of sow cooling options available to pork producers, from simple drip systems to full snout cooling setups. It explains how each system works, what it costs to run, how to install it correctly, and how to manage it through the hottest weeks of the year. The intended audience includes farrowing house managers, herd owners, and farm employees who want practical, field-tested guidance on keeping sows comfortable and productive during warm weather. ## At a Glance - Sows begin experiencing heat stress at effective temperatures above 70 to 75 degrees Fahrenheit, well below what many producers assume. - Drip cooling is the most cost-effective first step, using about 0.5 to 1 gallon per sow per hour during peak heat. - Snout cooling delivers air at 400 to 600 feet per minute directly to the sow's face and is the most effective individual cooling method. - Evaporative cooling pads work best in dry climates and can reduce incoming air temperature by 10 to 20 degrees. - Cooling sows improves feed intake, milk production, and litter weaning weights by 5 to 15 percent in summer months. - The critical heat window is from about 10 a.m. to 6 p.m., with the worst effects occurring when nighttime temperatures fail to drop below 75 degrees. - Monitoring should include sow respiration rate, feed intake, water consumption, and room temperature at sow level, not thermostat height. - Most cooling system failures trace back to clogged nozzles, misdirected airflow, or thermostats placed in the wrong location. ## Why Sows Overheat in Farrowing Houses Sows are particularly vulnerable to heat stress because they have a high metabolic rate, a thick layer of subcutaneous fat that traps body heat, and a limited ability to sweat. Swine have functional sweat glands only in their snouts, so they rely primarily on panting and behavioral adjustments to shed excess heat. In a farrowing crate, the sow cannot wallow, seek shade, or move to a cooler spot. She is confined to a small space, often on a solid concrete floor that retains heat, and she is producing large amounts of metabolic heat from lactation. A lactating sow produces roughly 20 to 30 percent more body heat than a gestating sow. Milk production requires enormous energy, and that energy conversion generates heat. On top of that, the farrowing room itself tends to be warm because piglets need temperatures around 90 degrees Fahrenheit for the first week of life. This creates a direct conflict between piglet needs and sow comfort. The room must be warm enough for the litter but cool enough to keep the sow eating and producing milk. The upper critical temperature for a lactating sow is approximately 70 to 75 degrees Fahrenheit. Above that range, the sow begins to pant and reduce feed intake to lower her heat production. For every degree above the upper critical temperature, feed intake can drop by 1 to 2 percent. A sow that should eat 14 to 16 pounds per day during peak lactation might eat only 8 to 10 pounds during a heat wave. That lost intake translates directly into reduced milk output, lighter weaning weights, and a longer return to estrus after weaning. Heat stress also affects the piglets indirectly. A heat-stressed sow is more restless, lies down and gets up more often, and is less attentive to her litter. This increases the risk of crushing. Sows that are panting heavily may also stand in awkward positions that trap piglets. In severe cases, heat stress can trigger agalactia, a failure of milk production that requires immediate veterinary attention. The financial impact of heat stress is substantial. A 10 percent reduction in weaning weight across a 1,000 sow farm can mean thousands of dollars in lost revenue per year. Add in longer wean-to-estrus intervals, reduced conception rates, and higher sow mortality during summer months, and the cost of inadequate cooling becomes clear. ## How Heat Moves Through a Farrowing House Understanding heat transfer helps explain why some cooling methods work better than others. Heat moves in four ways. Radiation is heat transfer between surfaces without direct contact. A hot ceiling or a warm wall radiates heat toward the sow. Conduction is heat transfer through direct contact, such as a sow lying on a warm concrete floor. Convection is heat transfer through moving air, which is why a breeze feels cool. Evaporation is heat loss through moisture changing from liquid to vapor, which is how sweating and panting cool the body. Sows lose heat through all four pathways, but the relative importance changes with temperature. At moderate temperatures, radiation and convection handle most heat loss. As the room temperature approaches skin temperature, around 95 degrees Fahrenheit, radiation and convection become less effective. Evaporation becomes the [dominant](/blog/careers/dominant-definition-biology) cooling mechanism. This is why drip cooling and snout cooling, which both enhance evaporative heat loss, are so effective in warm weather. The building itself plays a major role in heat stress. Poorly insulated roofs radiate heat downward during the day. Dark-colored roofing absorbs more solar energy than light-colored roofing. Inadequate ventilation allows heat to build up at the ceiling level, creating a layer of hot air that slowly radiates down to the animals. Exhaust fans that are undersized or dirty move less air than rated. Inlet baffles that are misadjusted create dead zones where air barely moves. The floor also matters. Solid concrete floors absorb heat during the day and release it slowly at night. In naturally ventilated buildings, this can be an advantage in cooler weather because the floor stores heat from the day and keeps the room warm overnight. In hot weather, the same floor keeps the room warm after the sun goes down. Fully slatted floors allow more air movement around the sow and reduce conductive heat gain from the floor surface. ## The Four Main Cooling Approaches Sow cooling systems fall into four broad categories. Each has strengths and weaknesses, and most well-managed farrowing houses use a combination of two or more approaches. The first approach is increased air movement through ventilation. This includes tunnel ventilation, stir fans, and snout coolers. Moving air removes heat by convection and enhances evaporative cooling from the sow's skin and respiratory tract. Ventilation is the foundation of any cooling strategy because it also removes moisture, ammonia, and carbon dioxide from the room. The second approach is evaporative cooling of the air itself. This includes evaporative cooling pads and high-pressure fogging systems. These systems cool the incoming air before it reaches the animals. They work best in dry climates where the air can absorb more moisture. In humid conditions, evaporative cooling provides less benefit because the air is already close to saturation. The third approach is direct evaporative cooling of the sow. This includes drip cooling systems that wet the sow's back and neck, and misting systems that spray fine droplets into the air around the sow. These systems cool the sow directly through evaporation of water from her skin. They are effective even in relatively humid conditions because the water evaporates from the sow's body, not from the air. The fourth approach is conductive cooling, which includes cooled floor pads or water-cooled mats. These systems remove heat through direct contact between the sow and a cool surface. They are less common in commercial production because of cost and maintenance concerns, but they can be useful in specialized situations. ## Ventilation as the Foundation No cooling system works well in a building with poor ventilation. Before investing in drip coolers or snout coolers, make sure the basic ventilation system is functioning correctly. The ventilation system has two primary jobs in summer. First, it must remove heat generated by the sows and the building itself. Second, it must provide enough air movement over the sows to enhance convective and evaporative heat loss. In a tunnel-ventilated building, air speed at sow level should reach 200 to 300 feet per minute during peak summer conditions. In naturally ventilated buildings, stir fans can provide localized air movement where the tunnel system cannot reach. Check the ventilation system before hot weather arrives. Clean fan blades and shutters, replace worn belts, and verify that fan capacity matches the building design. Test the static pressure to confirm that the building is not over-ventilated or under-ventilated. Inspect inlet baffles to ensure they are opening fully and directing air across the ceiling so it mixes with room air before dropping to animal level. A common mistake is setting ventilation rates based on thermostat readings at human height. Sensors should be placed at sow level, about 12 to 18 inches above the floor. The temperature at sow level can be 5 to 10 degrees warmer than at head height because of heat rising from the animals and the floor. Tunnel ventilation is the most effective ventilation strategy for hot weather. It moves large volumes of air in one direction through the building, creating a wind-chill effect that helps sows shed heat. The system works by placing exhaust fans at one end of the building and inlets at the other end. Air enters through the inlet end, travels down the length of the building, and exits through the fans. For tunnel ventilation to work properly, the building must be relatively airtight except for the designated inlets. Gaps around doors, curtain openings, or fan housings short-circuit the airflow and create dead zones. The inlet area must match the fan capacity. A rule of thumb is 1 square foot of inlet area for every 600 to 800 cubic feet per minute of fan capacity, though this varies with building design. Stir fans, also called circulation fans or mixing fans, are useful in naturally ventilated buildings or as a supplement to tunnel ventilation. They create air movement at animal level without moving large volumes of air through the building. Place stir fans so they create a consistent breeze across the sows' backs and heads. Fans mounted high in the ceiling do little for the sows because the air movement dissipates before reaching floor level. ## Drip Cooling Sows Drip cooling is the most common and most cost-effective method for cooling sows in farrowing crates. The system works by dripping water onto the sow's neck and shoulders, where it evaporates and removes heat from the skin surface. The evaporative cooling effect can reduce the sow's effective temperature by 10 to 15 degrees Fahrenheit. A basic drip cooling system consists of a water supply line, a solenoid valve, a timer or thermostat controller, and drip nozzles positioned above each crate. The nozzles deliver water at a rate of about 0.5 to 1 gallon per hour per sow. The water should drip, not spray. A fine spray wets the sow too quickly and the water runs off before it can evaporate. A slow drip allows the water to spread over the skin and evaporate gradually. Position the drip nozzle directly above the sow's neck and shoulders, about 12 to 18 inches above her back. The water should land on the skin, not just on the hair. Sows have thick hair on their backs that can insulate the skin from the water. Some producers use a small brush or a drip pad to help spread the water across the skin surface. The controller should activate the drip system when the room temperature at sow level exceeds about 75 degrees Fahrenheit. Use a timer to cycle the system on and off, typically 1 to 2 minutes on and 5 to 10 minutes off. The goal is to keep the sow's back wet without soaking the floor or the piglets. During extreme heat, the system may run continuously. Monitor the drip system daily during hot weather. Check each nozzle for clogs. Hard water causes mineral buildup that blocks the small orifices. Clean nozzles with a brush or replace them as needed. Check the water lines for leaks and the solenoid valves for proper operation. One concern with drip cooling is wetting the piglets. Position the drip nozzle so water falls only on the sow's back and neck. If the sow moves forward in the crate, the water may miss her and fall on the floor or the piglet zone. Some producers install a drip tray or a small shield to direct the water. Others position the nozzle slightly behind the sow's shoulders so that when she stands, the water falls behind her, and when she lies down, it falls on her back. Drip cooling works in both naturally ventilated and mechanically ventilated buildings. It is especially effective when combined with air movement from fans. The moving air speeds up evaporation from the wet skin, increasing the cooling effect. Without air movement, the water evaporates slowly and the cooling benefit is reduced. ## Snout Cooling Systems Snout cooling is a more aggressive cooling method that delivers high-velocity air directly to the sow's face. The system uses small fans or air outlets mounted in front of each crate that blow air at 400 to 600 feet per minute toward the sow's snout. This air movement enhances evaporative cooling from the sow's respiratory tract and skin, and it also provides convective cooling. The sow's snout is one of the most effective heat exchange surfaces on her body. The snout has a dense network of blood vessels close to the surface, and it is the only place on the sow's body with functional sweat glands. Moving air across the snout removes heat efficiently and stimulates the sow's natural cooling mechanisms. Snout cooling systems come in two basic designs. The first uses a small fan mounted on the front of the crate, blowing air across the sow's face. The second uses a duct system with individual outlets at each crate, connected to a central fan. The duct system is more efficient for large rooms because it uses fewer, larger fans that are easier to maintain. A typical snout cooling outlet delivers about 100 to 200 cubic feet per minute of air per crate. The air speed at the sow's snout should be high enough to feel like a strong breeze but not so high that it creates a draft on the piglets. Position the outlet so the air stream hits the sow's face when she is lying down, which is when she is most vulnerable to heat stress. Snout cooling is most effective when the incoming air is cooler than the room air. In hot weather, the air coming from outside may be 90 degrees or warmer. Moving hot air across the sow's face still provides some benefit because it enhances evaporative cooling from the respiratory tract. But the benefit is much greater if the air is first cooled by evaporative pads or if the system draws air from a cooler part of the building. Some snout cooling systems use a combination of air movement and water misting. A fine mist is injected into the air stream, and the droplets evaporate as they travel toward the sow. This provides both convective and evaporative cooling. These systems are more complex and require careful management to avoid wetting the piglets or creating slippery floors. Snout cooling is more expensive to install than drip cooling, but it is also more effective in severe heat. Many producers use both systems together, with drip cooling providing the primary cooling effect and snout cooling providing additional air movement and respiratory cooling. ## Evaporative Cooling Pads Evaporative cooling pads, also called evaporative cool cells or pad-and-fan systems, cool the incoming air before it enters the building. The system consists of a porous pad material, a water distribution system, and a collection sump. Air is drawn through the wet pads, and as the water evaporates, it absorbs heat from the air, lowering the air temperature. Evaporative cooling pads can reduce incoming air temperature by 10 to 20 degrees Fahrenheit, depending on the humidity level. In a dry climate with relative humidity below 50 percent, the cooling effect is substantial. In a humid climate with relative humidity above 70 percent, the cooling effect is minimal because the air is already close to saturation. The pad system requires a continuous water supply and a recirculation pump. Water is distributed across the top of the pads and flows down through the pad material. The pump recirculates water from the sump at the bottom back to the top. A float valve maintains the water level in the sump and replaces water lost to evaporation. Pad maintenance is critical for performance. The pads collect dust, algae, and mineral deposits over time. Dirty pads restrict airflow and reduce cooling efficiency. Clean the pads at least once per year, and replace them when they show signs of deterioration. The water distribution system should be checked regularly for clogged holes and uneven flow. Evaporative cooling pads work best in tunnel-ventilated buildings where all incoming air passes through the pads. The pads are installed at the inlet end of the building, and the exhaust fans pull air through them. The cooled air travels down the building, warming as it moves past the animals. The sows near the inlet end get the coolest air, while those near the exhaust end get warmer air. One limitation of evaporative cooling pads is that they increase humidity inside the building. The added moisture can make the air feel muggy and can slow evaporative cooling from the sows' skin. In most cases, the temperature reduction outweighs the humidity increase, but producers in humid climates should monitor the situation carefully. ## High-Pressure Fogging Systems High-pressure fogging systems use fine mist nozzles to atomize water into tiny droplets that evaporate quickly in the air. The evaporation cools the air, similar to evaporative cooling pads, but without the bulky pad material. Fogging systems can be installed in the ceiling or along the walls of the farrowing house. The key to an effective fogging system is droplet size. The nozzles must produce droplets small enough to evaporate before they fall to the floor. Droplets that are too large wet the floor and the animals, creating a mess and potentially chilling the piglets. High-pressure systems operating at 800 to 1,000 psi produce the finest droplets. Fogging systems work best in dry climates. In humid conditions, the droplets evaporate slowly, and the system may actually increase the humidity without providing much cooling. Some producers use fogging as a supplement to other cooling methods, running it only during the hottest part of the day. The main disadvantage of fogging systems is the potential for wetting the piglets. The fine droplets can drift into the piglet zone and chill the litter. To minimize this risk, position the fogging nozzles high in the ceiling and run the system only when the room is warm enough that the droplets evaporate quickly. Some systems use a controller that adjusts the fogging cycle based on humidity levels. ## Conductive Cooling Systems Conductive cooling systems remove heat from the sow through direct contact with a cool surface. The most common design uses water-cooled mats or pads placed under the sow in the farrowing crate. Cool water circulates through the mat, drawing heat away from the sow's body. These systems are effective because they cool the sow through conduction, which works independently of air temperature and humidity. A sow lying on a cool mat can lose significant amounts of heat even when the room is hot and humid. The cooling effect is greatest on the parts of the body in direct contact with the mat. Conductive cooling systems are more expensive to install and maintain than drip or snout cooling. The mats must be durable enough to withstand the sow's weight and the constant movement in the crate. The water circulation system requires a chiller or a source of cool water, which adds to the energy cost. The main advantage of conductive cooling is that it does not wet the sow or the piglets. There is no added humidity in the room, and no risk of chilling the litter. This makes it an attractive option for producers who have struggled with the moisture issues associated with drip or fogging systems. Conductive cooling is not widely used in commercial production, but it has a place in specialized situations. It may be useful for high-value sows, for research facilities, or for producers in humid climates where evaporative cooling is less effective. ## Designing a Cooling Strategy for Your Farrowing House The best cooling strategy depends on your climate, your building design, and your budget. Start by evaluating your current situation and identifying the biggest opportunities for improvement. First, measure the actual conditions in your farrowing house during hot weather. Place temperature and humidity sensors at sow level in several locations throughout the room. Record readings at different times of day to understand the daily pattern. Note which areas of the room are warmest and which sows show the most signs of heat stress. Second, evaluate your ventilation system. Is it moving enough air? Are there dead zones where air barely moves? Are the fans and inlets in good condition? If the ventilation system is inadequate, no amount of additional cooling will solve the problem. Fix the ventilation first, then add supplemental cooling. Third, decide on your primary cooling method. For most producers, drip cooling is the best first investment because it is inexpensive, effective, and easy to install. If you already have drip cooling and sows are still showing signs of heat stress, consider adding snout cooling or improving air movement with fans. Fourth, plan for the hottest days of the year. The system should be sized to handle peak conditions, not average conditions. A system that works well in June may be inadequate in August. Build in a margin of safety so you have capacity to spare during extreme heat events. Fifth, develop a standard operating procedure for hot weather. Define when to turn on the cooling system, how to adjust it as temperatures rise, and what to do if a component fails. Train your staff on the procedure and post it in the farrowing house. ## Installation Steps for a Drip Cooling System A drip cooling system is a straightforward DIY project for most farms. The following steps describe a typical installation. Step one: Determine the water supply. The system needs a clean water source with adequate pressure and flow. A 1,000 psi pressure regulator may be needed to reduce the pressure from the main water line to a level suitable for the drip nozzles. Install a filter to remove sediment and debris that could clog the nozzles. Step two: Plan the layout. Decide where to run the main water line and where to place the drip nozzles. The line should run above the crates, out of reach of the sows. Use PVC pipe or flexible tubing that can withstand the water pressure and the heat in the building. Step three: Install the solenoid valve and controller. The solenoid valve controls the flow of water to the system. Connect it to a timer or a thermostat controller that activates the system when the temperature exceeds the set point. The controller should be mounted where it is easy to access and where the temperature sensor can be placed at sow level. Step four: Run the water line above the crates. Support the line securely so it does not sag or swing. Install a drip nozzle above each crate, positioned over the sow's neck and shoulders. Use a tee fitting to connect each nozzle to the main line. Step five: Test the system. Turn on the water and check each nozzle for proper flow. The water should drip at a steady rate, not spray or stream. Adjust the flow rate if needed. Check for leaks at all connections. Step six: Set the controller. Set the temperature set point at about 75 degrees Fahrenheit at sow level. Set the timer for 1 to 2 minutes on and 5 to 10 minutes off. Adjust the cycle based on the weather and the condition of the sows. Step seven: Monitor and adjust. Check the system daily during hot weather. Look for clogged nozzles, leaks, and sows that are not getting wet. Adjust the timer cycle as temperatures rise and fall. ## Common Mistakes in Sow Cooling Several recurring mistakes reduce the effectiveness of sow cooling systems. The most common is placing the temperature sensor at the wrong location. A thermostat mounted at head height or on a wall reads a different temperature than the air at sow level. The sensor should be at sow level, in a location that represents the average conditions in the room, and shielded from direct sunlight or drafts. Another common mistake is using drip nozzles that produce too much water. A steady stream of water runs off the sow before it can evaporate, wasting water and wetting the floor. The system should produce a slow drip that allows the water to spread over the skin and evaporate gradually. If the sow's back is dripping water onto the floor, the flow rate is too high. Neglecting nozzle maintenance is another frequent problem. Mineral deposits and algae clog the small orifices in drip nozzles, reducing flow or stopping it entirely. Some producers do not notice a clogged nozzle until the sow shows visible signs of heat stress. Clean or replace nozzles regularly, and check them daily during hot weather. Positioning the drip nozzle incorrectly is also common. If the nozzle is too far forward, the water falls on the sow's head and face, which she may not like. If it is too far back, the water misses the sow entirely when she lies down. The nozzle should be positioned so the water lands on the neck and shoulders, which are the areas with the best blood supply and the most effective heat exchange. Using the cooling system only during the hottest part of the day is another mistake. Heat stress builds over hours, and a sow that is already overheated takes time to recover. Start the cooling system early in the morning, before the room temperature reaches the set point. Run it consistently through the afternoon and evening, and consider running it at night if the room does not cool down. Ignoring the piglets is a serious mistake. Some cooling methods, especially fogging and misting, can wet the piglets and cause chilling. Piglets have limited ability to regulate their body temperature, and a chilled piglet is more susceptible to disease and crushing. Always consider the effect of the cooling system on the litter, not just on the sow. Finally, some producers rely entirely on one cooling method and ignore the others. A cooling system is most effective when it combines air movement, evaporative cooling, and good building design. A drip system without adequate ventilation provides limited benefit. A snout cooling system without drip cooling may not be enough during extreme heat. ## Monitoring and Recordkeeping Effective heat stress management requires regular monitoring and careful recordkeeping. The goal is to catch problems early, before they affect sow performance and piglet survival. Monitor the following indicators daily during hot weather: Respiration rate is the most direct indicator of heat stress. A sow at rest should breathe 20 to 40 times per minute. When the respiration rate exceeds 60 to 80 breaths per minute, the sow is heat stressed and needs additional cooling. Count breaths for 30 seconds and multiply by two. Check sows at the same time each day, preferably in the afternoon when heat stress is most severe. Feed intake is a lagging indicator of heat stress. A sow that reduces feed intake today may have been heat stressed yesterday. Track feed intake per sow per day, and compare it to the expected intake for the stage of lactation. A sustained drop in intake is a warning sign. Water consumption also changes with heat stress. Sows drink more water when they are hot, and they may drink less if the water is warm. Check water flow rates and water temperature regularly. Water should be below 80 degrees Fahrenheit for optimal consumption. Room temperature and humidity should be recorded at least twice daily, at the hottest and coolest times of the day. Record the readings at sow level, not at human height. Also record the temperature in the piglet zone, which should be maintained at 90 degrees for the first week of life. Sow behavior is a useful indicator. Heat-stressed sows are restless, pant heavily, stand in unusual positions, and may lie in their water troughs or manure. They may also be aggressive toward their piglets or show reduced maternal behavior. Weaning weights are the ultimate measure of cooling effectiveness. Track average weaning weight by month, and compare summer months to the rest of the year. A drop in weaning weight during summer indicates that heat stress is affecting milk production. Also track wean-to-estrus interval and conception rate, which are affected by the sow's nutritional status during lactation. Keep a cooling system log that records when the system was running, any adjustments made, and any maintenance performed. This log helps identify patterns and predict when problems are likely to occur. It also provides documentation for management decisions about cooling system upgrades. ## When to Call a Veterinarian or Extension Agent Most heat stress problems can be managed with good cooling practices and attentive monitoring. However, certain situations warrant professional assistance. Call a veterinarian immediately if you see signs of agalactia, which is a failure of milk production. Affected sows have swollen, hard udders, and the piglets are restless, hungry, and losing weight. Agalactia is a medical emergency that requires prompt treatment to save the litter. Call a veterinarian if multiple sows show severe respiratory distress. Panting is normal in hot weather, but labored breathing, open-mouth breathing, or blue discoloration of the ears or snout are signs of a more serious problem. These symptoms may indicate heat stroke, which can be fatal if not treated promptly. Call a veterinarian if you see signs of disease in the piglets. Heat stress weakens the immune system, and piglets from heat-stressed sows may be more susceptible to scours, meningitis, or other infections. An outbreak of disease in the farrowing house requires professional diagnosis and treatment. Call an extension agent or a ventilation specialist if you cannot identify the cause of persistent heat stress problems. A building assessment can identify issues with ventilation, insulation, or cooling system design that are not obvious to the untrained eye. Many land-grant universities offer free or low-cost building assessments through their extension services. Call an extension agent if you are considering a major investment in cooling equipment. An agent can help you evaluate your options, calculate the expected return on investment, and connect you with manufacturers and suppliers. They can also provide information about cost-share programs or grants that may be available for energy-efficient upgrades. Call a veterinarian or extension agent if you are unsure about the correct diagnosis. Heat stress can mimic other conditions, and a wrong diagnosis can lead to ineffective treatment and unnecessary losses. A professional assessment is always a good investment when the health of your herd is at stake. ## Frequently Asked Questions **At what temperature should I start cooling my sows?** Start supplemental cooling when the temperature at sow level reaches about 75 degrees Fahrenheit. This is the upper critical temperature for a lactating sow. Above this point, the sow begins to reduce feed intake and show other signs of heat stress. Do not wait until the room feels uncomfortable to you. Sows are more sensitive to heat than humans, and they cannot remove their clothing or move to a cooler spot. **How much water does a drip cooling system use?** A drip cooling system uses about 0.5 to 1 gallon per sow per hour during peak cooling periods. For a 100 sow farrowing house running the system 8 hours per day, that is 400 to 800 gallons per day. The actual usage depends on the flow rate of the nozzles and the duration of operation. Monitor water usage and compare it to expected values to catch leaks or clogged nozzles. **Can I use drip cooling on young sows or gilts?** Yes, drip cooling works on all sows regardless of age or parity. Gilts are often more sensitive to heat stress because they have less body mass to buffer temperature changes. They may also be less accustomed to the cooling system and may need a few days to get used to the water dripping on their backs. Start the system early in the summer so the sows can acclimate gradually. **Will drip cooling chill the piglets?** Drip cooling should not chill the piglets if the system is installed and managed correctly. Position the drip nozzle over the sow's neck and shoulders so the water does not fall into the piglet zone. The piglets have their own heat source in the form of heat lamps or heat pads. As long as the piglet zone stays at 90 degrees Fahrenheit, the piglets will not be chilled by the cooling system. **How effective is snout cooling compared to drip cooling?** Snout cooling and drip cooling work through different mechanisms. Snout cooling provides convective cooling and enhances evaporative cooling from the respiratory tract. Drip cooling provides evaporative cooling from the skin surface. Both are effective, and many producers use them together. Snout cooling is generally more expensive to install but may provide better results in severe heat. Drip cooling is the best first investment for most producers. **Can I use evaporative cooling pads in a humid climate?** Evaporative cooling pads are less effective in humid climates because the air is already close to saturation. The cooling effect is proportional to the difference between the wet-bulb and dry-bulb temperatures. In a humid climate, this difference is small, so the temperature reduction is minimal. If you live in a humid area, focus on ventilation, drip cooling, and snout cooling instead of evaporative pads. **How often should I clean my drip nozzles?** Clean or inspect drip nozzles at least once per week during the cooling season. Hard water causes mineral buildup that can clog the small orifices. Remove the nozzles and soak them in a vinegar solution or a commercial descaler to dissolve the deposits. Replace nozzles that are badly clogged or damaged. During peak heat, check the nozzles daily to catch clogs early. **What is the best way to measure heat stress in sows?** The most practical measure is respiration rate. Count the number of breaths in 30 seconds and multiply by two. A sow at rest should breathe 20 to 40 times per minute. Above 60 breaths per minute indicates heat stress. Also monitor feed intake, which drops when sows are hot. Skin temperature, measured with an infrared thermometer, can provide additional information but is less practical for routine monitoring. ## Related Farming Guides This section will be populated with links to related farming guides on farrowing management, swine ventilation, piglet care, and seasonal herd health planning. Please check back for updated content. ## Related Clinical & Scientific Guides * [Pig Enrichment Programs and Behavior Monitoring](/knowledge/animal-farming/swine/pig-enrichment-programs-and-behavior-monitoring) * [Swine Handling Facility Design for Safe Pig Movement](/knowledge/animal-farming/swine/swine-handling-facility-design-safe-pig-movement) * [Swine Feeding Management for Grow-Finish Pigs](/knowledge/animal-farming/swine/swine-feeding-management-for-grow-finish-pigs) ## References - National Pork Board: https://www.pork.org/ - USDA APHIS Swine Health: https://www.aphis.usda.gov/livestock-poultry-disease/swine - FAO Pig Production: https://www.fao.org/pig-production-and-products/en/ - FAO Animal Production and Health: https://www.fao.org/animal-production/en/ - WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/ > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.