# Lactating Sow Feed Intake and Water Management ## Key Takeaways - Lactating sow feed intake is a critical determinant of milk yield, litter weaning weight, and subsequent reproductive efficiency, directly influenced by physiological demands, environmental factors (especially heat stress), and management practices. - Water intake is intrinsically linked to feed consumption and milk production; ensuring clean, cool water at adequate flow rates (minimum 2 L/min) is paramount to prevent dehydration, constipation, and reduced feed intake. - Systematic daily observation protocols, including feed disappearance, water consumption patterns, sow behavior, and body condition scoring (e.g., backfat depth), are essential for early detection of intake declines and proactive intervention. - Environmental management, particularly maintaining ambient temperatures within the thermoneutral zone (16-22°C for sows), is crucial, as heat stress significantly depresses appetite and milk production, impacting sow and litter performance. - Farrowing records, including litter size, birth weights, and health events, alongside parity and body condition data, provide the necessary context for setting realistic feed intake targets and identifying sows at risk of excessive body reserve mobilization. - Failure patterns such as early lactation refusal (constipation, pain) or mid-lactation drops (mastitis, lameness, heat stress) necessitate prompt veterinary investigation, potentially including diagnostic tests like serum chemistry to rule out subclinical diseases or metabolic imbalances. --- Lactating sow feed intake directly determines milk yield, litter weaning weight, and the sow's subsequent reproductive efficiency. Water intake is tightly coupled to feed consumption and must be managed simultaneously. Systematic daily observation of feed and water intake, thermal environment, litter size, body condition, and farrowing records provides the basis for proactive intervention when intake declines. This article presents a management framework for monitoring and adjusting these interdependent factors to maintain sow and litter health and productivity. ## At a Glance | Element | Key Observation | Management Focus | | --- | --- | --- | | Feed intake | Daily feed disappearance per sow | Adjust formulation, feeding method, and timing | | Water intake | Flow rate, consumption pattern, water temperature | Ensure clean, cool water at adequate flow | | Temperature | Barn ambient temperature, sow respiration rate and posture | Provide ventilation, cooling, and adjust stocking | | Litter size | Number of pigs nursed, litter growth rate | Match feed allocation and energy density to demand | | Body condition | Backfat depth, visible fat cover, weight change | Increase feed amount or energy density | | Farrowing records | Litter history, parity, health events, gestation feed | Plan pre-farrow and lactation feeding targets | ## System Context ### Physiological Demands of Lactation The lactating sow must support her own maintenance, the rapid growth of a large litter, and the recovery of body reserves depleted during farrowing. Energy requirements increase substantially, particularly in the first two weeks of lactation. Feed intake must rise correspondingly to prevent excessive maternal tissue loss. Research on energy utilization in pregnant and lactating sows provides a framework for modeling these requirements ([Energy utilization in pregnant and lactating sows: modeling of energy requirements](https://api.elsevier.com/content/abstract/scopus_id/0025377771)). Functional amino acids and fatty acids also play a direct role in supporting milk production and litter growth ([Functional amino acids and fatty acids for enhancing production performance of sows and piglets](https://api.elsevier.com/content/abstract/scopus_id/33847094225)). The pattern of feed intake and associated metabolic and endocrine changes differentially affect postweaning fertility in primiparous sows ([Pattern of Feed Intake and Associated Metabolic and Endocrine Changes Differentially Affect Postweaning Fertility in Primiparous Lactating Sows](https://api.elsevier.com/content/abstract/scopus_id/0030641230)). These findings underscore the need for meticulous feeding management from farrowing through weaning. ### Environmental Influences on Feed Intake Thermal environment is a critical determinant of voluntary feed intake. High ambient temperatures consistently depress feed consumption in lactating sows, with multiparous animals being particularly susceptible ([Influence of High Ambient Temperatures on Performance of Multiparous Lactating Sows](https://api.elsevier.com/content/abstract/scopus_id/0033174495)). Heat stress reduces appetite and can cause a cascade of metabolic effects that compromise milk output, litter weight gain, and subsequent reproductive cycles. Barn temperature, humidity, and ventilation must be managed to keep the sow within her thermoneutral zone, which is approximately 16 to 22 degrees Celsius for lactating animals depending on stage and parity. Daily observation of sow respiration rate, posture, and water intake provides early indicators of heat stress. When feed intake declines despite appropriate environmental management, veterinary and nutritional consultation is warranted to investigate other contributing factors such as disease or feed quality. ## Planning Decisions ### Feed Formulation and Presentation Feeding programs should be designed to meet the sow's changing requirements across lactation. Diets should be nutrient-dense, with appropriate levels of energy, crude protein, lysine, and minerals to support milk synthesis without imposing an excessive metabolic burden on the sow. The feeding method,liquid, dry meal, or pelleted,affects intake and must be chosen based on facility constraints, labor availability, and observed sow preferences. Liquid feeding can increase voluntary intake in some herds, but it requires rigorous management to prevent feed spoilage and variable nutrient delivery. Consistency in diet composition and feeding schedule supports stable intake patterns and reduces stress. General principles of sow nutrition are available from FAO Animal Production and Health resources ([FAO Animal Production and Health](https://www.fao.org/animal-production/en/)). ### Water Delivery and Quality Water is the most essential nutrient for lactating sows and is directly linked to feed intake and milk production. Lactating sows have high water requirements for milk synthesis and metabolic heat dissipation. Clean, cool water must be available at all times, with adequate flow rates from nipples or bowls. Flow rate should be checked routinely, rates below one liter per minute can significantly limit voluntary water intake. Water temperature above 25 degrees Celsius reduces palatability and consumption. Any reduction in water intake can precipitate a corresponding drop in feed intake. Water quality should be assessed periodically for bacterial contamination, mineral content, and pH. Poor water quality can reduce consumption and introduce pathogens that affect sow and litter health. ## Core Management Framework ### Daily Observation Protocols Personnel should observe each sow for feed intake, water consumption, behavior, and physical condition at least once daily. Feed refusal, prolonged standing at the feeder, or reduced water usage are early warnings of potential problems that may require prompt investigation. [Body condition scoring](/knowledge/animal-farming/farm-management/body-condition-scoring-a-tool-for-feed-management) at farrowing, mid-lactation, and weaning provides objective data for adjusting feed allocation and identifying sows at risk of excessive weight loss. Scoring systems based on visual assessment and backfat palpation are widely used and should be standardized within the operation. Farrowing records that include litter size, piglet birth weights, and health events are essential for setting realistic feed intake targets for each sow. Trends in feed intake by parity, season, and litter size help identify systemic issues such as feed quality variation, disease outbreaks, or environmental missteps. When feed intake falls consistently below expected levels or body condition deteriorates despite corrective measures, professional veterinary diagnosis is necessary to rule out metabolic disease, infection, or system failure. Disease surveillance data from the USDA National Animal Health Monitoring System provide context for regional disease risks ([USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms)), and veterinary standards for swine health management are outlined in the WOAH Terrestrial Animal Health Code ([WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/)). Clinical guidance on lactation disorders can be found in the Merck Veterinary Manual ([Merck Veterinary Manual](https://www.merckvetmanual.com/)). ## Facilities and Environmental Management The farrowing environment directly modulates lactating sow feed intake through thermal, spatial, and social factors. Elevated ambient temperatures suppress voluntary feed consumption because sows reduce metabolic heat production when thermal comfort is exceeded. The relationship between heat stress and intake depression is well documented, multiparous sows exposed to high ambient temperatures show marked declines in daily feed intake, which compromises milk output and subsequent reproductive performance ([Influence of High Ambient Temperatures on Performance of Multiparous Lactating Sows](https://api.elsevier.com/content/abstract/scopus_id/0033174495)). Evaporative cooling systems, drip coolers, snout coolers, and increased ventilation rates help maintain intake during warm weather, but each intervention must be matched to facility design and local climate conditions. Flooring type and sanitation also influence lying behavior and comfort, which indirectly affect feeding bouts. Wet or soiled floors discourage sows from standing at the feeder, whereas well,drained, non,slip surfaces promote normal activity patterns. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) provides guidance on optimal farrowing room temperatures (typically 18,22 °C for sows, with a separate creep area for piglets at 32,35 °C) and emphasizes that deviations from these ranges decrease sow feed intake and increase piglet mortality. Water management is inseparable from feed intake. Sows require continuous access to clean, palatable water, and flow rates should be checked daily. Low water flow reduces voluntary water consumption, which leads to constipation, diminished feed intake, and reduced milk synthesis. Inadequate water delivery also concentrates urine, increasing the risk of urinary tract infections. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) outlines general principles for [livestock water quality](/knowledge/animal-farming/farm-management/water-quality-livestock-testing-treatment), including microbial standards and acceptable levels of dissolved solids. Practical monitoring on farm involves measuring nipple drinker flow (targeting at least 2 L per minute) and observing the sow’s drinking behavior. If sows spend excessive time at the drinker or push the bowl without drinking, the water supply or palatability should be investigated. ## Nutrition and Water Interactions Lactation imposes the highest nutrient demand of the sow’s production cycle. To meet energy and amino acid requirements, feed intake must rise rapidly after farrowing. A delayed or insufficient intake increase leads to negative energy balance, excessive body fat mobilization, and reduced subsequent litter size and weaning,to,estrus interval. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) publications describe feeding strategies that match energy density with expected intake capacity, noting that high,fiber diets can limit energy intake if the sow cannot consume sufficient volume. Water intake is correlated with feed intake, sows drink approximately 2,3 L of water per kg of feed consumed. If feed intake falls, water consumption also drops, creating a reinforcing cycle of undernutrition. Offering water immediately after feed delivery encourages intake, especially during the first days post,farrowing when appetite is suppressed. Functional amino acids and fatty acids have been studied for their role in enhancing milk production and maintaining body condition. Supplementation with specific amino acids (e.g., arginine, glutamine, leucine) can improve mammary gland metabolism and support the sow’s immune function during the stress of lactation ([Functional amino acids and fatty acids for enhancing production performance of sows and piglets](https://api.elsevier.com/content/abstract/scopus_id/33847094225)). However, these additives are effective only when total dietary protein and energy are adequate. Over,formulation without accurate intake monitoring wastes resources and may not compensate for a voluntary feed intake deficit. Feed must be presented in a form that minimizes waste and sorting, pelleted or coarse meal diets are common, and feeders should be adjusted to prevent excessive spillage. ## Production,Stage Decisions Transition from gestation to lactation feeding requires a planned curve. Sows that are over,conditioned at farrowing have lower voluntary intake in lactation, increasing the risk of negative energy balance. Conversely, under,conditioned sows need aggressive feeding but may be physically limited by gut fill. A gradual increase of 0.5,1.0 kg per day after farrowing, reaching ad libitum or a pre,determined maximum by day 5 to 7, is a standard approach. Litter size is a major driver of feed intake requirements because milk production increases with the number of suckling piglets. Sows nursing larger litters have higher energy needs and, given adequate feeding management, will consume more feed. If feed intake does not increase proportionally with litter size, sows catabolize body reserves, and piglet weight gain suffers. Body condition scoring at weaning provides a key metric for evaluating the success of the feeding program. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resources include protocols for condition scoring (typically 1 to 5) that should be applied at farrowing and weaning to detect losses of more than 0.5,1.0 score units, which indicate inadequate energy intake. ## Records and Monitoring Accurate recordkeeping is essential for diagnosing feed intake failures. Daily feed allowance (offered) and refusal (orts) should be recorded per sow or per pen, along with water meter readings for the farrowing room. Individual sow feed intake is best measured using electronic feeding stations or weigh,backs from manual feeding. Farrowing records that include litter birth weight, number born alive, and parity allow calculation of expected intake based on lactation stage and litter demand. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides guidelines for data collection on swine operations, including lactation performance metrics that correlate with feed and water consumption. Comparing actual vs. expected intake highlights outliers that may need health intervention. For example, a primiparous sow that consumes <3 kg per day on day 7 of lactation is at high risk for post,weaning reproductive failure (__MASK_16__). Regular body weight or body condition scoring at weaning, combined with feed intake data, enables the herd veterinarian to adjust nutritional programs for the next cycle. ## Welfare Considerations Low feed intake is a welfare indicator because it often reflects heat stress, illness, or social competition. Sows that are unable to consume adequate feed experience hunger, increased stereotype behaviors (e.g., bar biting, sham chewing), and prolonged lying in unhygienic areas. Welfare assessment protocols in the WOAH code include monitoring of body condition, skin lesions, and signs of dehydration. Workers should be trained to recognize early signs of reduced feed intake: sows that remain at the feeder for short periods, leave feed untouched, or show increased vocalization when fed. Prompt intervention,such as checking water flow, offering a wet mash, or attending to health issues,prevents progression to severe negative energy balance, which compromises both sow and piglet welfare. ## Worker and Food Safety Feed and water management involve several food safety considerations. Mycotoxin contamination of stored feed reduces palatability and can cause feed refusal, vomiting, and immunosuppression. Regular testing of feed ingredients for aflatoxins, deoxynivalenol, and zearalenone is recommended. The __MASK_17__ details mycotoxin thresholds and clinical signs in swine. Water sources should be tested periodically for coliforms, nitrates, and total dissolved solids. Stagnant water lines or dirty drinkers harbor bacteria that cause enteric disease, further suppressing feed intake. Workers handling feed should practice hygiene to prevent introduction of pathogens. Feces or urine contamination of feed troughs can transmit agents such as _Escherichia coli_, which has been associated with diarrhea in piglets when virulent strains colonize the sow’s gut (__MASK_18__). Good cleaning protocols for feeders and water lines reduce this risk. ## Failure Patterns and Practical Monitoring Common patterns of feed intake failure include: - **Early,lactation refusal** due to constipation, pain from dystocia, or metritis. Sows that do not stand to eat within 6 hours after farrowing need examination. - **Mid,lactation drop** often linked to mastitis, lameness, or heat stress. Reduced water intake frequently precedes the feed drop. - **Persistent low intake** in primiparous sows, which may reflect inadequate gut capacity or inability to compete for feeder space. Practical monitoring should include daily visual checks of each sow’s feed consumption, water drinker function, and behavior. A simple checklist for farm workers can include: “Did the sow eat all offered feed within 30 minutes?” and “Is the drinker working without leakage?” Body condition scoring every two weeks during lactation, combined with a cumulative feed intake chart, allows early identification of sows that are losing excessive condition. These sows should be examined for underlying disease (e.g., urinary tract infection, lameness) and, if no cause is found, provided with a top,dress of extra fat or a high,energy supplement. Feed intake records also serve as a diagnostic tool for herd outbreaks: a sudden, synchronous drop across multiple sows often points to a common environmental problem (e.g., ventilation failure, feed contamination, or water outage). The energy utilization model published by the Elsevier database (1990) shows that lactating sows partition energy first to milk production, then to maintenance, and surplus is stored as body reserves. This hierarchy means that inadequate feed intake directly reduces milk yield and, eventually, sow body condition. By integrating facility management, water delivery, records, and daily observation, producers can maintain voluntary feed intake near genetic potential, thereby improving piglet growth, sow health, and subsequent reproductive performance. ## Health Observation During Lactation Systematic daily observation of lactating sows is essential for detecting deviations in feed intake and water consumption that signal health problems. A sow that leaves feed in the trough for two consecutive meals or reduces water intake by 20 percent or more warrants immediate attention. The __MASK_19__ emphasizes that acute drops in feed intake often precede clinical signs of disease such as fever, mastitis, metritis, or respiratory infection. Body condition scoring should be performed at farrowing and at weaning using a standardized 1 to 5 scale. The __MASK_20__ guidelines recommend that multiparous sows should not lose more than 0.5 units of condition over a 21-day lactation. Excessive loss indicates that dietary energy or protein intake was insufficient relative to milk production demand and litter size. Sows that lose more than one condition unit have a higher risk of prolonged weaning-to-estrus interval and reduced subsequent litter size. Litter size context is critical. A sow nursing 12 or more piglets has substantially higher nutrient requirements than one nursing 8 piglets. The __MASK_21__ demonstrates that sows with larger litters consume more feed but may still experience a negative energy balance if feed intake peaks too slowly. Therefore, producers must adjust feeding curves based on actual litter size and piglet weight gain, not solely on parity or farrowing date. Farrowing records provide the foundation for interpreting feed intake patterns. Records should include parity, gestation length, number of piglets born alive, stillbirths, mummies, birth weights, and weaning weights. When feed intake declines unexpectedly, these records help determine whether the reduction correlates with high ambient temperature, a large litter, or a subclinical health event. The __MASK_22__ recommends that producers record daily high and low barn temperatures and note any cooling system failures. Water management is closely tied to feed intake. Sows require 15 to 25 liters of water per day during lactation, and more under hot conditions. __MASK_23__ indicates that water availability directly influences voluntary feed intake, particularly in first-parity sows. Producers must verify that nipple drinkers deliver a flow rate of at least 2 liters per minute and that sows do not face competition from pen mates. Any reduction in water consumption should be investigated immediately, as dehydration rapidly reduces feed intake and milk production. ## Biosecurity Practices Biosecurity reduces the introduction and spread of pathogens that compromise feed intake and sow health. The __MASK_24__ outlines principles for isolation, sanitation, and movement control that apply to farrowing houses. All-in/all-out management of farrowing rooms is standard because it allows thorough cleaning and disinfection between groups. The __MASK_25__ resource emphasizes that persistent low-level disease is a common cause of suboptimal feed intake in lactating sows. Practice daily removal of unconsumed feed from troughs, especially in warm weather. Wet or spoiled feed promotes fungal growth and bacterial proliferation, which can cause feed refusal and digestive upset. Provide fresh feed at each meal and clean water lines regularly to prevent biofilm accumulation. The __MASK_26__ highlights that probiotic administration can reduce diarrhea incidence in sows and piglets, but hygiene remains the primary defense against enteric pathogens. Personnel should follow a defined traffic flow to avoid moving contamination from grower pens into farrowing rooms. Footwear, coveralls, and hand hygiene protocols reduce transmission of agents like porcine reproductive and respiratory syndrome virus and *Escherichia coli*. When disease is suspected, diagnostic samples should be collected before antimicrobials are administered. The __MASK_27__ provides detailed guidance on sample submission and biosecurity during outbreaks. ## Diagnostic and Veterinary Escalation When feed intake remains low despite corrective environmental and management measures, veterinary investigation is warranted. Diagnostic tests may include serum chemistry to assess hydration, electrolyte balance, and organ function. The __MASK_28__ (1999) shows that chronic heat stress alters metabolic profiles and reduces feed intake even when barn temperatures appear acceptable. Veterinary assessment should also rule out subclinical diseases such as chronic respiratory infection, urinary tract infection, or gastric ulcers. Farrowing records and body condition data must accompany any diagnostic submission. A herd history of poor feed intake that clusters in specific parity groups or seasons helps identify contributing factors. The __MASK_29__ discusses how metabolic and endocrine changes differ between sows that maintain high feed intake and those that reduce intake, affecting postweaning fertility. Tracking these patterns at the herd level can guide nutritional interventions. Uncertainty exists in predicting individual sow feed intake accurately. Genetic lines differ in appetite, and environmental interactions are complex. The __MASK_30__ review indicates that amino acid supplementation may improve feed intake in sows with low voluntary intake, but responses are variable and depend on baseline diet composition. Similarly, the __MASK_31__ energy model highlights that requirements vary widely with litter size and milk yield. Therefore, management recommendations must be tailored to individual farm conditions, and escalation to a nutritionist or veterinarian is appropriate when standard protocols fail. ## Sustainability Considerations Improving feed intake consistency during lactation contributes to production efficiency and reduces environmental impact. Sows that meet their energy and protein requirements produce more milk, wean heavier piglets, and return to estrus sooner. This reduces the number of non-productive days per sow per year and lowers the carbon footprint per weaned pig. The __MASK_32__ resources emphasize that efficient feed conversion in the breeding herd supports global food security by minimizing waste. Water management also has sustainability implications. Monitoring and repairing leaks, adjusting nipple drinker flow rates to meet but not exceed requirements, and using nipple bowls to reduce spillage conserve clean water. In regions facing water scarcity, these measures are critical. Furthermore, reducing the incidence of disease through biosecurity and good nutrition decreases the need for antimicrobial use, addressing concerns about antimicrobial resistance. Sustainable facilities incorporate cooling systems that maintain barn temperature at or below 20°C (68°F) for lactating sows. Passive ventilation, evaporative cooling pads, and drip coolers can be energy-efficient when designed correctly. Heat stress management also supports feed intake but also improves sow longevity, reducing replacement rate and the associated environmental costs of rearing replacement gilts. ## Frequently Asked Questions **1. What is the most common cause of low feed intake in lactating sows?** Environmental heat stress is the most common cause. High ambient temperatures reduce voluntary feed intake even before clinical signs appear. Cooling systems and feeding during cooler parts of the day help. **2. How much water should a lactating sow drink each day?** A lactating sow typically needs 15 to 25 liters per day, and up to 40 liters in hot weather. Flow rate from the nipple drinker must be at least 2 liters per minute. **3. When should I escalate a feed intake problem to a veterinarian?** If feed intake drops by 20 percent or more for two consecutive days, or if the sow shows signs of fever, mastitis, or lethargy, consult a veterinarian promptly. **4. Can litter size alone explain low feed intake?** Sows with large litters have higher nutrient demands, but they typically increase feed intake over the first 10 to 14 days. If intake plateaus or declines, investigate water availability, environmental temperature, and subclinical disease. **5. What record-keeping is essential for managing feed intake?** Daily feed offered, feed refused, water flow rates, barn temperature and humidity, farrowing data (parity, litter size, birth weights), and body condition scores at farrowing and weaning. **6. Is body condition loss always a problem?** Moderate loss (less than 0.5 units) is acceptable if the sow returns to condition before the next farrowing. Excessive loss (>1.0 unit) impairs fertility and may signal inadequate nutrition or underlying disease. **7. How does biosecurity affect feed intake?** Poor biosecurity allows enzootic diseases to circulate, causing subclinical infections that reduce appetite. All-in/all-out management, cleaning protocols, and visitor restrictions help maintain health and feed intake. **8. Can nutritional supplements improve feed intake in problem sows?** Some sows respond to added functional amino acids or fatty acids, but the effect is variable. Addressing environmental and management factors should come first. A nutritionist can help design targeted supplementation. ## Educational Veterinary Notice This information provides general guidance for managing lactating sow feed intake and water consumption. Individual herd conditions, genetic lines, and regional climates require adaptation. Producers should establish a relationship with a veterinarian and a qualified swine nutritionist to develop protocols specific to their operation. Routine health monitoring, accurate records, and prompt escalation of unresolved problems are the foundation of successful lactation management. The links to approved sources provide further detail on the topics discussed. ## Related Farming Guides - [Pig Farming Breeding Farrowing Nursery Grow Finish Nutrition And Biosecurity](/knowledge/animal-farming/swine/pig-farming-breeding-farrowing-nursery-grow-finish-nutrition-and-biosecurity) - [Farrowing House Preparation And Sow Care](/knowledge/animal-farming/swine/farrowing-house-preparation-and-sow-care) - [Newborn Piglet Care During The First 48 Hours](/knowledge/animal-farming/swine/newborn-piglet-care-during-the-first-48-hours) - [Pig Farm Biosecurity Plan](/knowledge/animal-farming/swine/pig-farm-biosecurity-plan) - [Production Records For Pig Farms](/knowledge/animal-farming/swine/production-records-for-pig-farms) ## 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 and Further Reading - [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) - [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) - [Merck Veterinary Manual](https://www.merckvetmanual.com/) - [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.