# Gilt Development and Breeding Readiness ## Key Takeaways - Gilt development is a multi-faceted process requiring precise management of selection, growth trajectory, structural soundness, and health acclimation to optimize lifetime sow productivity. Selection criteria at weaning and at 100 days of age focus on structural conformation (e.g., teat number, leg structure) and growth rate, with culling of gilts exhibiting conformational defects or failing to meet minimum growth standards. - Controlled growth management is critical, utilizing phase-feeding of amino acids to achieve target body weight (135-160 kg) and backfat depth (12-18 mm at P2) at breeding (210-240 days of age) without excessive fat deposition, which impairs lactation and increases mortality. - Structural soundness is paramount, with lameness being a leading cause of involuntary culling; protocols include gait scoring (1-5 scale), with gilts scoring 4 or higher removed, and emphasis on genetic selection and appropriate flooring to prevent hoof lesions and joint issues. - Health acclimation involves controlled exposure to farm-specific pathogens (e.g., PRRSV, *Mycoplasma hyopneumoniae*) over 4-8 weeks, often through contact with infected animals or attenuated vaccines, to build immunity before breeding, complemented by vaccination series completion. - Breeding readiness is confirmed by observing the second or third estrus at appropriate age and weight, stimulated by daily boar exposure, with record-keeping of estrus dates, age, and weight essential for program evaluation and culling decisions. - Biosecurity during gilt development necessitates dedicated facilities separate from gestating sows, with adequate space (0.75-1.0 m²/gilt), all-in/all-out management, and strict quarantine protocols for incoming animals to prevent pathogen introduction and transmission. --- Gilt development management is a systematic process encompassing genetic selection, controlled growth, structural soundness evaluation, disease acclimation, and breeding readiness confirmation, all of which collectively determine subsequent sow lifetime productivity and herd retention. The biological foundation for a successful breeding herd is established before first service, making intentional gilt development programs a critical component of commercial swine operations. ## At a Glance | Aspect | Core Principle | Supporting Reference | |--------|----------------|----------------------| | Selection | Choose gilts with sound feet and legs, adequate vulva development, and correct teat number and spacing to maximize longevity. | [Merck Veterinary Manual](https://www.merckvetmanual.com/) | | Growth Management | Control feed intake to achieve target body weight at puberty without excessive fat deposition, using phase-feeding of amino acids. | [Impacts of amino acid nutrition on pregnancy outcome in pigs](https://api.elsevier.com/content/abstract/scopus_id/77954901360) | | Structural Soundness | Evaluate locomotion and hoof integrity, cull gilts with conformational defects that predispose to premature removal. | [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) | | Health Acclimation | Expose gilts to farm-specific pathogens through controlled contact with weaned pigs or feedback to build immunity before breeding. | [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) | | Breeding Readiness | Confirm second or third estrus at appropriate age and weight, use boar exposure to stimulate and detect estrus. | [Current strategies for reproductive management of gilts and sows in North America](https://api.elsevier.com/content/abstract/scopus_id/84928007637) | | Record Keeping | Track age, weight, estrus dates, vaccinations, and removal reasons to monitor program effectiveness and guide culling decisions. | [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) | ## System Context and Planning Decisions ### Economic and Biological Importance Gilts that enter the breeding herd poorly developed or rushed to first service carry higher risk of low litter size, increased stillbirth rates, and early culling due to lameness or reproductive failure. The relationship between adolescent growth trajectory and adult reproductive function is well documented: inadequate protein and amino acid intake during early development impairs follicular growth and reduces embryo survival during the first gestation. Conversely, overconditioning at breeding is associated with reduced feed intake during lactation and increased weaning-to-estrus intervals. Therefore, the planning framework must balance age, weight, and body composition targets that align with the genetic line and facility constraints. ### Planning for Replacement Rate and Facilities Annual herd replacement rates commonly range from 40 to 50 percent, requiring a continuous flow of replacement gilts. This flow demands dedicated gilt development facilities separate from gestating sows to allow precise feeding and health management. Space allowances of 0.75 to 1.0 square meters per gilt for group housing are standard, with additional area for boar exposure pens. The decision to purchase gilts from a specific genetic supplier or to raise own replacements involves tradeoffs in biosecurity risk, genetic improvement speed, and cost control. Acclimation space must be available to hold incoming gilts for 3 to 6 weeks before introducing them to the main herd, allowing for vaccination series completion and pathogen exposure under controlled conditions. ## Core Management Framework ### Selection at Weaning and at 100 Days of Age Initial selection occurs at weaning, focusing on structural conformation and teat qualification. Gilts with fewer than six functional teats per side, inverted teats, or severe leg weaknesses are removed from the candidate pool. A second selection at approximately 100 days of age (50 to 70 kg body weight) evaluates growth rate, body condition, and continued structural soundness. Gilts that fail to meet minimum growth standards or that develop lameness during this phase are culled. Genetic selection indices that combine growth, backfat depth, and loin muscle area can guide retention decisions, although individual farm experience with specific lines remains essential. ### Growth Trajectory and Body Composition Goals Controlled feeding programs utilizing a sequence of gestation and lactation diets formulated to meet amino acid requirements at each developmental stage are applied. Ad libitum feeding during the early growth period (20 to 80 kg) supports lean tissue deposition, followed by a phase of controlled gain (80 to 130 kg) where energy intake is limited to prevent excessive fat accumulation while still allowing for continued protein deposition. The typical breeding weight target is 135 to 160 kg at 210 to 240 days of age, with a backfat depth of 12 to 18 mm measured at the P2 site. Deviation from this range,either lighter or heavier than recommended at a given age,indicates a need for diet adjustments or health evaluation. Respiratory disease, particularly enzootic pneumonia caused by *[Mycoplasma hyopneumoniae](/knowledge/bacteria/livestock-bacteria/mycoplasma-hyopneumoniae-enzootic-pneumonia-pigs)*, can significantly reduce average daily gain and weaken structural integrity, delaying puberty onset and increasing the risk of early culling. ### Structural Soundness Evaluation Protocols Lameness is a leading cause of involuntary culling in commercial herds, with conformational defects such as post-leggedness, buck knees, and splayed toes being heritable. Formal gait scoring using a 1 to 5 scale (1 = normal, 5 = non-weight bearing) is performed at each selection point. Gilts scoring 4 or higher are removed immediately. Hoof trimming and treatment of visible lesions such as heel cracks or white line separation may salvage some animals, but the prevention focus remains on genetic selection and floor surface management, including avoidance of abrasive concrete and limiting time on fully slatted floors. After introduction to the breeding facility, continued daily observation for lameness is required, with early intervention using nonsteroidal anti-inflammatory drugs and stall rest as indicated by veterinary assessment. ### Health Acclimation and Vaccination Strategies Acclimation begins at arrival using a multistep exposure plan. Vaccination against porcine circovirus type 2, *Mycoplasma hyopneumoniae*, and [porcine reproductive and respiratory syndrome](/knowledge/viruses/general/porcine-reproductive-and-respiratory-syndrome-genomic-surveillance-and-vaccine-strategies-using-bioinformatics) virus is scheduled to complete before first breeding, with timing determined by the gilt age and farm disease prevalence. Controlled exposure through contact with replacement gilts that have been deliberately infected with farm-specific strains of PRRSV or attenuated live virus vaccines may be employed under veterinary supervision. This process requires 4 to 8 weeks and must be completed before gilts are moved to the breeding facility to prevent transmission to the gestating sow population. Serological monitoring is used to confirm seroconversion for target pathogens, although complete protection against all field strains cannot be guaranteed. Professional consultation with a herd veterinarian is necessary when interpreting acclimation protocols, particularly for farms with unstable disease status or in regions with emerging pathogen strains. ## Facilities and Environment Housing design during gilt development directly affects growth rate, structural soundness, and subsequent reproductive performance. Group housing with adequate space allowance permits natural social interactions and exercise, which supports bone and muscle development. Recommended floor space per gilt varies according to body weight and production system, but facilities must allow all animals to lie down simultaneously without restriction. Solid flooring in lying areas reduces the risk of hoof lesions, while slatted areas must be properly maintained to avoid foot injuries. Ventilation systems that maintain air quality and temperature within the thermoneutral zone for growing gilts reduce respiratory disease pressure. The USDA National Animal Health Monitoring System has documented that respiratory disease, including enzootic pneumonia, can impair growth performance and delay puberty onset ([USDA NAHMS](https://www.aphis.usda.gov/livestock-poultry-disease/nahms)). Producers should monitor air exchange rates, ammonia levels, and humidity to minimize pathogen load. Environmental enrichment such as manipulable materials (e.g., straw, rooting substrates) supports behavioral welfare and reduces stress-related aggression. Acclimation of replacement gilts to the breeding herd environment should occur at least 4 to 6 weeks before first breeding. This period allows adequate time for exposure to resident pathogens, thereby enabling immunity development before the physiological demands of pregnancy. Separation of acclimation facilities from the main breeding area, with all-in, all-out management, helps control disease transmission. The WOAH Terrestrial Animal Health Code emphasizes biosecurity protocols for incoming animals, including quarantine and vaccination as determined by herd health status ([WOAH Terrestrial Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/)). Escalation to a veterinarian is warranted if signs of respiratory disease or poor adaptation appear during acclimation. ## Nutrition and Water Precision nutrition during gilt development influences also growth rate but also body composition, mammary development, and reproductive tract maturation. Controlled energy intake prevents excessive fat deposition, which is associated with reduced feed efficiency and impaired lactation capacity. Lysine and other essential amino acids must be supplied in adequate ratios to support lean tissue accretion and reproductive organ development. A review on amino acid nutrition in sows indicates that specific amino acid profiles during gestation can affect subsequent litter size and piglet birth weight ([Impacts of amino acid nutrition on pregnancy outcome in pigs](https://api.elsevier.com/content/abstract/scopus_id/77954901360)). For developing gilts, nutrition programs should target a body condition score of 3.0 to 3.5 on a 5-point scale at first breeding. Vitamin and mineral premises including calcium, phosphorus, copper, zinc, and selenium are critical for skeletal integrity and hoof health. Water supply must be unrestricted, flow rates and drinker placement should allow all gilts to drink without competition. Daily water intake can vary from 4 to 8 liters depending on temperature and feed intake. If water consumption drops unexpectedly, investigate potential disease or water system failure. Professional nutritional consultation is advised when formulating diets to match genetic potential and facility constraints. ## Production-Stage Decisions The timing of first breeding is a key decision that influences lifetime productivity and sow longevity. Breeding at too young an age or low body weight increases the risk of dystocia, small litters, and early culling. Conversely, delaying breeding beyond optimal criteria raises non-productive days and feed costs. Many commercial programs target breeding between 220 and 250 days of age at a body weight of 135 to 150 kilograms, with at least three estrous cycles experienced before service. The review of gilt management for fertility and longevity emphasizes that age at puberty and number of estrous cycles prior to breeding are positively associated with litter size and retention in the herd ([Gilt management for fertility and longevity](https://api.elsevier.com/content/abstract/scopus_id/85071120790)). Boar exposure beginning at approximately 160 to 170 days of age stimulates puberty onset. Daily exposure to a mature boar for 15 to 30 minutes should occur in a well-lit, non-slippery pen. Record the date of each observed estrus to predict the third estrus for timed artificial insemination. Board veterinary oversight is necessary if more than 10% of gilts fail to show estrus by 200 days of age, as this may indicate nutritional, environmental, or genetic issues. ## Records Systematic record-keeping is essential for evaluating gilt development programs and identifying problem areas. Individual identification of each gilt allows tracking of birth date, weaning age, growth trajectory, vaccination history, health treatments, estrus dates, and breeding outcomes. Group-level data such as average daily gain, body weight at key ages, and percentage achieving estrus by target age provide benchmarks for management decisions. Records should be reviewed at regular intervals,monthly or after each cohort completes acclimation. The information from longitudinal records supports culling decisions and genetic selection. Producers who do not maintain accurate records cannot objectively assess the effectiveness of their gilt management program. The Merck Veterinary Manual advises that incomplete records are a common obstacle to troubleshooting reproductive failure patterns ([Merck Vet Manual](https://www.merckvetmanual.com/)). If data indicate a trend of low conception rates or high removals before second parity, a systematic investigation involving reproduction specialists is warranted. ## Welfare Gilt welfare is compromised when housing, nutrition, handling, or health management fails to meet physiological and behavioral needs. Chronic stress from overcrowding, aggressive social mixing, or poor handling increases circulating cortisol, which can delay puberty and impair immune function. Lameness is a leading cause of premature culling in gilts. Hoof lesions, joint infections, and osteochondrosis dissecans reduce mobility and breeding success. Monitoring gait daily during feeding periods allows early identification of affected animals. The effect of enzootic pneumonia on growth performance illustrates the importance of respiratory health for overall welfare ([Effect of enzootic pneumonia of pigs on growth performance](https://api.elsevier.com/content/abstract/scopus_id/0021984842)). Gilts that exhibit labored breathing or coughing should be isolated and evaluated by a veterinarian. Use of low-stress handling techniques,such as avoiding electric prods and using boards or flags,decreases injury risk to both animals and workers. Welfare audits using standardized scoring systems help identify facility deficiencies and training gaps. ## Worker and [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Personnel working with gilts must be trained in safe animal handling and biosecurity protocols. Injuries from bites, kicks, or being crushed occur when individuals are not vigilant or when facility design lacks escape routes. All workers should wear appropriate clothing and footwear that can be disinfected between groups. Pregnant women should avoid contact with farrowing areas due to the risk of [toxoplasmosis](/knowledge/parasites/pet-parasites/toxoplasmosis-feline-transmission-public-health-clinical-management), though direct zoonotic transmission from gilts to humans is low when basic hygiene is practiced. Food safety considerations extend to the eventual market pigs derived from the breeding herd. Antibiotic use in gilts should be judicious, and withdrawal periods respected if medications are administered for treatment. The FAO Animal Production and Health guidelines encourage integrated herd health programs that minimize residues and antimicrobial resistance ([FAO Animal Production](https://www.fao.org/animal-production/en/)). Should a gilt require surgical intervention or emergency euthanasia, only qualified personnel should perform these procedures, and carcass disposal must follow local regulations. ## Failure Patterns Common patterns of failure in gilt development include low puberty attainment, high early culling, and poor first-litter performance. Post-mortem examination of genital organs from sows with reproductive disturbances has revealed that ovarian cysts, uterine infections, and congenital abnormalities are frequent findings in animals considered subfertile ([Post-mortem Examination of Genital Organs from Sows with Reproductive Disturbances](https://api.elsevier.com/content/abstract/scopus_id/0031301553)). These conditions may not be detectable during routine estrus detection, emphasizing the value of diagnostic investigation when a cohort fails to meet reproductive targets. Another failure pattern is excessive body fat at breeding, which correlates with reduced feed intake during lactation and higher sow mortality. Lameness and leg weakness often stem from inadequate floor surfaces, improper nutrition during growth, or genetic predisposition. When cumulative removal rates exceed 20% before parity 2, a comprehensive review of gilt rearing practices,including growth rate, vaccination protocols, and boar exposure management,should be performed in consultation with a swine veterinarian. ## Practical Monitoring Routine monitoring of gilt development should incorporate both visual observation and objective measurement. Weigh or estimate body weight monthly so that growth trajectories can be adjusted through diet changes. Apply [body condition scoring](/knowledge/animal-farming/farm-management/body-condition-scoring-a-tool-for-feed-management) every two weeks during the acclimation period. Maintain a daily log of estrus detection events, noting signs such as reddening, swelling, and standing behavior. Conduct gait scoring on a weekly basis, classifying animals from sound to severely lame. Any gilt that does not recover from lameness within two weeks should be examined by a veterinarian for joint infection or fracture. Respiratory health can be monitored by recording cough index scores in the morning. If coughing scores rise above a herd-specific threshold, lung ultrasound or necropsy of representative animals may be indicated. The current strategies for reproductive management in North America highlight the importance of monitoring weaning-to-estrus interval and conception rates as key performance indicators for the breeding herd ([Current strategies for reproductive management of gilts and sows in North America](https://api.elsevier.com/content/abstract/scopus_id/84928007637)). Because gilt development programs vary between farms, each unit should establish its own baseline values and response protocols. Professional veterinary involvement is necessary when health or performance metrics deviate significantly from these baselines. ## Health Observation and Monitoring Daily visual observation of gilts during the acclimation and breeding preparation period is a fundamental management practice. Health checks should focus on feed intake, fecal consistency, respiratory character, locomotion, and vulva discharge. Gilts that fail to maintain adequate feed intake over 24 hours require immediate evaluation. Chronic inappetence may indicate underlying disease or metabolic disturbance. The relationship between enzootic pneumonia and reduced growth performance has been documented in pigs, and subclinical respiratory infections can delay the onset of puberty or reduce conception rates. Observation should be systematic, with personnel trained to recognize subtle signs of disease. Body condition scoring using a standardized scale (1 to 5) helps identify gilts that are overconditioned or underconditioned. Both extremes negatively affect lifetime productivity and breeding readiness. Structural soundness assessment should continue throughout the development period. Gilts that develop lameness or difficulty rising may have underlying osteochondrosis or joint lesions that compromise their ability to breed, farrow, and nurse. The postmortem examination of genital organs from sows with reproductive disturbances has identified urogenital infections as a common cause of subfertility in pooled sow herds. Early detection and removal of affected gilts can reduce the introduction of chronic reproductive pathogens into the breeding herd. ## Biosecurity and Acclimation Biosecurity protocols during gilt development should prevent introduction of new pathogens while allowing controlled exposure to the resident herd’s microbial environment. The acclimation period, typically four to eight weeks, should be managed in facilities physically separate from the sow herd. During this time, gilts are exposed to resident manure, placental tissues, or cull sows to stimulate immunity against endemic agents such as porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and [swine influenza](/knowledge/veterinary-medicine/clinical-methods/swine-swine-influenza-diagnosis-management) virus. The efficacy of acclimation depends on the timing and dose of exposure, pathogen strain characteristics, and the gilt’s prior immune status. Because standardized protocols are not available for all production systems, producers should consult with their herd veterinarian to design an acclimation program based on herd-specific disease prevalence and diagnostic monitoring. Movement of gilts into the breeding herd should occur only after they are confirmed to be clinically healthy and have completed the acclimation period. Quarantine of incoming replacement gilts is a separate procedure that prevents introduction of novel pathogens. The WOAH Terrestrial Animal Health Code provides guidance on quarantine measures for international movements, but domestic quarantine should follow veterinary recommendations tailored to local disease risks. ## Diagnostic and Veterinary Escalation When gilts fail to exhibit estrus by target age (commonly 200 to 240 days) or have repeated returns to estrus after breeding, a systematic diagnostic investigation is warranted. First, review breeding records to confirm heat detection accuracy and service timing. Second, evaluate vaccination status, photoperiod management, and boar exposure. Third, conduct a veterinary assessment that may include ultrasound examination of reproductive tracts, serological testing for [porcine parvovirus](/knowledge/viruses/livestock-viruses/porcine-parvovirus), leptospirosis, and PRRS virus, and fecal culture for Brachyspira or Lawsonia if diarrhea is present. The Merck Veterinary Manual describes common reproductive pathogens affecting swine and their diagnostic methods. Veterinary escalation is indicated when greater than 5% of gilts develop anestrus after the target age, when conception rates fall below herd benchmarks, or when clinical signs such as fever, respiratory distress, or abortion clusters appear. Diagnostic laboratory submissions can include paired serology, tissues from necropsy of affected animals, or preputial fluids from boars. The USDA National Animal Health Monitoring System collects data on swine health and management practices that can inform regional disease prevalence. ## Managing Uncertainty The transition from gilt to sow carries inherent uncertainty. Individual variation in age at puberty, ovulation rate, and response to hormonal programs is influenced by genotype, nutrition, social environment, and health history. There is no single threshold for age, weight, or backfat that guarantees successful breeding in every gilt. Producers should monitor rolling averages of gilt breeding performance instead of rigid individual targets. When herd data are insufficient to identify causes of reduced breeding readiness, a controlled evaluation with the herd veterinarian is preferable to implementing untested treatments or altering management systems. Records of interventions, outcomes, and culling reasons should be maintained for at least two years to allow retrospective analysis. ## Sustainability Considerations Gilt development directly influences the sustainability of the breeding herd through its effect on longevity. Gilts that are selected for structural soundness, good maternal behavior, and stable temperament tend to have longer productive lives, reducing replacement costs and the environmental footprint associated with rearing new gilts. The FAO Animal Production and Health division emphasizes that efficient livestock production systems minimize waste and resource use. Culling decisions that remove nonperforming gilts early, instead of after first parity, improve overall herd efficiency. Additionally, managing nutrition to avoid excessive fat deposition reduces feed costs while maintaining adequate body reserves for lactation. ## Frequently Asked Questions **Q: At what age should a gilt be observed for first estrus?** A: Most producers begin daily boar exposure from 160 to 170 days of age. Puberty typically occurs between 180 and 210 days, but this varies by genetics and management. **Q: How long after weaning should a gilt return to estrus?** A: First parity gilts can return to estrus 4 to 7 days after weaning. If return is delayed beyond 10 days, evaluate weaning diet, body condition, and health. **Q: What causes gilts to fail to show estrus?** A: Common causes include inadequate boar exposure, heat stress, poor nutrition, obesity, and chronic disease. Diagnostic workup with a veterinarian is recommended when the problem persists. **Q: Can a gilt be bred on her first estrus?** A: Breeding on the first estrus is possible, but many producers prefer to skip it to allow additional growth and maturity. The decision should be based on target weight, body condition, and herd goals. **Q: What is the ideal weight for breeding a gilt?** A: Target weights of 135 to 160 kg at breeding are common in commercial production. Lighter gilts may have smaller litters and higher farrowing complications, while heavier gilts may be overconditioned. **Q: How much boar exposure is needed to stimulate estrus?** A: Daily fenceline contact with a mature, active boar for 10 to 20 minutes is effective. Overexposure can lead to habituation, rotate boars if possible. **Q: What vaccinations should a replacement gilt receive?** A: Vaccinations should be tailored to the herd health plan and may include porcine parvovirus, leptospirosis, erysipelas, and PRRS virus. Consult a veterinarian for a customized protocol. **Q: How long before breeding should a gilt be acclimated to the sow herd?** A: A minimum of four weeks is typical, with six to eight weeks preferred to allow development of immunity and adaptation to the resident microbial community. ## Educational Veterinary Notice The information provided in this article is intended for educational use by producers and veterinary professionals. Management decisions should be made in consultation with a licensed veterinarian who has knowledge of the specific herd, local disease prevalence, and regional regulations. Diagnostic testing and treatment protocols must follow current veterinary and regulatory guidelines. ## 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.