# Mycotoxin Risk Management in Swine Feed ## Key Takeaways - Swine are highly susceptible to mycotoxins due to their monogastric physiology and limited detoxification capacity, leading to subclinical effects on feed intake, immunity, and reproduction that necessitate systematic monitoring. - Mycotoxin contamination originates in the field and persists through storage; prevention strategies focus on pre-harvest practices (e.g., crop rotation, fungicides) and post-harvest storage conditions (moisture <14%, temperature <15°C) to inhibit fungal growth. - Detection relies on representative sampling (compositing 5-10 subsamples per batch) and validated laboratory analysis (ELISA for screening, LC-MS/MS for definitive quantitation), as mycotoxins are heterogeneously distributed. - Mitigation strategies include feed dilution, clay-based binders (effective for aflatoxins, variable for others), and nutritional adjustments, but these are secondary to prevention and do not eliminate the toxin. - Susceptibility varies by production stage, with nursery pigs and breeding stock being most vulnerable to specific toxins like deoxynivalenol (DON) and zearalenone (ZEN), respectively, requiring tailored risk assessment and stricter action levels. - Comprehensive risk management integrates ingredient procurement, on-farm storage, sampling protocols, laboratory interpretation, and coordinated action by veterinarians and nutritionists, with accurate record-keeping crucial for traceback and problem resolution. --- Mycotoxin risk management in swine feed demands an integrated strategy that spans ingredient procurement, on-farm storage, sampling protocols, laboratory interpretation, and coordinated action by veterinarians and nutritionists. Pigs are among the most sensitive livestock species to mycotoxin exposure, and subclinical effects on feed intake, immunity, and reproductive performance often escape detection without systematic monitoring. ## At a Glance | Component | Primary Concern | Management Priority | |-----------|-----------------|---------------------| | Aflatoxins | Hepatotoxicity, immunosuppression | Ingredient sourcing, storage moisture control | | Deoxynivalenol (DON) | Feed refusal, vomiting, gut barrier disruption | Sampling representativeness, blending limits | | Zearalenone (ZEN) | Estrogenic effects, reproductive failure | Risk assessment for breeding stock | | Fumonisins | Pulmonary edema, hydrothorax | Corn screening, additive use | | Ochratoxin A | Nephrotoxicity | Raw material selection (barley, wheat) | | Multi-mycotoxin co-exposure | Synergistic effects, diagnostic ambiguity | Comprehensive testing, professional consultation | ## System Context: The Mycotoxin Challenge in Swine Production Mycotoxin contamination of swine feed originates in the field and persists through storage, processing, and feeding. *Fusarium* species produce deoxynivalenol, zearalenone, and fumonisins under cool, wet conditions, while *Aspergillus* and *Penicillium* species generate aflatoxins and ochratoxin A during warm, humid storage. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) framework emphasizes that contamination is rarely uniform within a grain lot, creating sampling challenges that are especially consequential for pigs. Swine are disproportionately affected because their monogastric physiology limits detoxification capacity and because chronic low-level exposure is endemic in many production regions. A review of worldwide *Fusarium* mycotoxin contamination of cereal grains and animal feed documented that deoxynivalenol and zearalenone are routinely present in corn, wheat, and barley at concentrations that reduce growth performance and alter immune function. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) notes that pigs fed fumonisin-contaminated corn develop pulmonary edema and hydrothorax, a syndrome first reproduced experimentally and published in a seminal study. Zearalenone exerts estrogenic effects through competitive binding to estrogen receptors, leading to vulvovaginitis, rectal prolapse, and infertility in gilts and sows as described in a risk assessment of that mycotoxin. Uncertainty arises because mycotoxin contamination is spatially variable, clinical signs are often non-specific, and analytical methods differ in sensitivity. Professional escalation to a veterinary diagnostic laboratory is indicated when herd-level performance declines are unexplained by infectious disease or management deficits. ## Planning Decisions: Integrating Risk Management into Feed Procurement Risk management begins before grain is purchased. Nutritionists and veterinarians should collaborate on ingredient specifications that account for regional mycotoxin prevalence. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resource underscores that weather events during flowering and harvest are primary determinants of *Fusarium* contamination. Feed mills and producers can adjust sourcing to avoid high-risk growing areas in a given season. Storage planning is equally critical. Moisture content above 14 percent in grain and above 12 percent in finished feed promotes mold growth and mycotoxin accumulation. Temperature cycling within storage bins creates condensation zones where *Aspergillus* species proliferate. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) does not address mycotoxins directly but provides principles for hazard identification in feed supply chains that are applicable. Veterinarians and nutritionists share responsibility for interpreting risk in the context of herd health history. Breeding herds are more vulnerable to zearalenone and aflatoxin exposure than grow-finish populations, and the threshold for intervention should be lower when sows or gilts are involved. A systematic review of zearalenone toxicity, occurrence, metabolism, and regulation confirms that even transient exposure during critical reproductive windows can impair conception and embryo survival. ## Core Management Framework: Prevention, Detection, and Mitigation A three-part framework structures the response to mycotoxin risk. **Prevention** targets the pre-harvest and storage environment. Field practices such as crop rotation, tillage, and fungicide application reduce *Fusarium* inoculum. Grain drying to 13 percent moisture within 24 hours of harvest stops further mold metabolism. Cool, dry storage at 15 to 20°C and less than 70 percent relative humidity slows fungal growth. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides surveillance data that can inform regional risk assessments. **Detection** depends on representative sampling and validated laboratory analysis. Because mycotoxins are distributed heterogeneously, a single grab sample underestimates contamination. The likelihood that a negative test reflects a truly negative lot increases with sample size and the number of subsamples composited. ELISA-based screening is rapid and cost-effective for deoxynivalenol and aflatoxins, while LC-MS/MS is required for definitive quantitation of multiple mycotoxins in a single run. The [PubMed record 42245464](https://pubmed.ncbi.nlm.nih.gov/42245464/) discusses aspects of mycotoxicosis diagnosis that include analytical verification of feed samples paired with clinical assessment. Uncertainty in interpretation is common. A feed sample that tests below an action limit does not guarantee that every pig receives a safe dose, because intake variation and individual susceptibility differ. When clinical signs persist despite low analytical results, the veterinarian should consider mycotoxin synergism, other feed toxins, or alternative causes. Professional escalation to a veterinary toxicologist or feed safety specialist is warranted. **Mitigation** encompasses physical, chemical, and biological strategies but must be applied with realistic expectations. Feed dilution with uncontaminated grain reduces dietary concentration but does not eliminate the toxin. Clay-based binders are effective for aflatoxins but show variable efficacy for zearalenone and fumonisins. The review on zearalenone detoxification notes that microbial biotransformation and enzymatic degradation are under investigation but not uniformly approved or validated for commercial use. Nutritionists should adjust ration formulation to account for reduced palatability when deoxynivalenol is present at moderate levels. Increasing dietary protein or adding synthetic sweeteners may partially offset feed refusal, but this approach masks instead of solves the problem. The [PubMed record 42382785](https://pubmed.ncbi.nlm.nih.gov/42382785/) and related literature emphasize that mitigation must begin with ingredient quality control, not end with post-contamination remediation. ## Facilities and Environment Mycotoxin risk begins before grain enters the feed mill. Storage facilities for corn, wheat, barley, and soy products must maintain moisture below 14% and temperature below 15°C to limit fungal growth during storage. Aeration systems that create uniform airflow through stored grain reduce hot spots where *Fusarium* and *Aspergillus* species proliferate. Open-sided bins or uncovered piles expose grain to rain and humidity, conditions that favor mycotoxin production after harvest. Concrete floors with drainage prevent moisture wicking into bagged ingredients. Feed bins on farm should be cleaned between batches, especially when switching from corn-based to wheat-based diets, because residue in bin corners harbors contaminated fines that elevate toxin load in subsequent feed deliveries. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) emphasizes that facility design directly influences the moisture profile of stored feed ingredients and thus the probability of mycotoxin formation. Temperature fluctuations inside feed mills and on-farm storage cause condensation on bin walls. This moisture drips onto grain surfaces and creates localized zones of high water activity. Regular inspection of bin interiors and removal of caked material reduces the risk of concentrated toxin pockets. Liquid feed systems present additional challenges: prolonged retention of feed in lines and tanks at ambient temperature permits fermentation and fungal overgrowth. Flushing lines with sanitizing solution between fills and limiting holding time to less than 12 hours are standard precautions. ## Nutrition and Water Feed formulation can partially mitigate mycotoxin effects but cannot replace prevention. Adding mycotoxin binders,aluminosilicates, bentonites, or yeast cell-wall derivatives,to diets reduces intestinal absorption of aflatoxins and some *Fusarium* toxins. However, binders show limited efficacy against zearalenone, deoxynivalenol, and fumonisins because these toxins are absorbed rapidly in the upper gastrointestinal tract. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) notes that binders must be matched to the specific toxin profile, a general adsorbent may not protect against multiple contaminants simultaneously. Nutrient density adjustments, such as increasing protein and energy levels, help pigs compensate for reduced feed intake caused by deoxynivalenol, but this strategy does not eliminate toxic effects on immune function. Water contamination is an underrecognized route of mycotoxin exposure. Surface water sources and wells near grain storage or moldy crop residue can carry soluble mycotoxins, particularly deoxynivalenol and zearalenone, into drinking lines. Testing water for mycotoxins is rarely performed on commercial farms, yet the [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) recommends including water analysis in comprehensive risk assessments when feed-related problems persist despite corrective measures. Pigs consuming contaminated water may show clinical signs identical to those from feed, and the combined dose from both sources can exceed safe thresholds even when each individual source appears acceptable. ## Production-Stage Decisions Susceptibility to mycotoxins varies across production stages. Nursery pigs (weaning to 25 kg) are most vulnerable because of immature hepatic detoxification systems and higher feed intake per unit body weight. A review on zearalenone toxicity ([Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone](https://api.elsevier.com/content/abstract/scopus_id/33751251394)) explains that estrogenic effects in prepubertal gilts cause vulvovaginitis and delayed puberty at levels that produce no observable effect in finisher pigs. Therefore, mycotoxin screening must be more stringent for breeding and pre-weaning diets. Grow-finish pigs can tolerate somewhat higher contamination levels but still suffer reduced average daily gain and feed efficiency when deoxynivalenol exceeds approximately 2 ppm in complete feed,a threshold that varies with individual farm health status and concurrent stressors. Breeding herds require particular attention to zearalenone and fumonisins. Zearalenone interferes with follicle development and embryo survival, field reports link contaminated corn screenings to anestrus and pseudopregnancy in gilts. Fumonisins, described in [Pulmonary Edema and Hydrothorax in Swine Produced by Fumonisin B1](https://api.elsevier.com/content/abstract/scopus_id/0025461819), cause acute pulmonary edema in sows, a condition that can be mistaken for bacterial pneumonia or heart failure. Gestation diets should be sourced from lots with documented low total fumonisin levels. Replacement gilts exposed to moderate zearalenone levels during the rearing phase may exhibit reduced lifetime reproductive performance, even if immediate clinical signs are absent. ## Records Documentation of each feed batch,including source, date of manufacture, ingredient composition, and mycotoxin test results,enables traceback when clinical problems emerge. Farms that maintain digital or paper logs linking feed delivery tags to pen-level observation records can identify temporal clusters of reduced intake, poor gain, or unusual mortality. [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) surveys indicate that operations with systematic feed records respond faster to feed quality issues and reduce economic losses. Records should also note feed mill cleaning schedules, storage conditions, and any treatment with binders or mold inhibitors. Veterinary investigation of suspected mycotoxicosis relies on reconstructing the feed history, without accurate records, the cause may remain ambiguous. ## Welfare Mycotoxicosis compromises swine welfare through multiple mechanisms. Deoxynivalenol induces feed refusal, leading to hunger and metabolic stress. Zearalenone causes vulvar swelling, tenesmus, and discomfort in prepubertal gilts. Fumonisins disrupt sphingolipid metabolism, damaging liver and lung tissue, and clinical cases involve dyspnea, cyanosis, and death. Even subclinical exposure alters immune function, increasing susceptibility to secondary infections and prolonging recovery from common diseases. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) portal highlights that welfare assessments in swine should include monitoring for signs of feed refusal, abnormal vulvar development, and unexplained respiratory distress, all of which can indicate underlying mycotoxin problems. Prompt removal of contaminated feed is the primary intervention to restore welfare, but some effects may be irreversible once clinical signs appear. ## Worker and [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Feed handling exposes workers to dust containing mycotoxins, particularly aflatoxins and ochratoxin A, which are carcinogenic via inhalation. Use of dust masks and adequate ventilation in feed mixing and dispensing areas reduces exposure risk. Pork safety concerns arise because certain mycotoxins,aflatoxin residues can appear in liver, and ochratoxin A can accumulate in kidney and muscle tissues. Although regulatory limits for mycotoxins in porcine tissues exist in some jurisdictions, the [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) and [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) advise that preventing mycotoxin entry into the feed chain is more reliable than relying on withdrawal periods or tissue testing. Workers should be trained to recognize moldy feed and to report signs of contamination without handling suspect material unnecessarily. ## Failure Patterns Common failures in mycotoxin risk management include delayed sampling, reliance on visual inspection alone, and testing only a single toxin. Molds grow unevenly in stored grain, a sample from the top of a bin may be clean while the bottom is heavily contaminated. Failure to sample multiple locations and depths leads to underestimation of the average toxin level. Similarly, testing only for aflatoxins while ignoring *Fusarium* toxins leaves the operation vulnerable, because climate conditions that favor one group often suppress another. [A review of worldwide contamination of cereal grains and animal feed with Fusarium mycotoxins](https://api.elsevier.com/content/abstract/scopus_id/0033620433) documents that co-occurrence of deoxynivalenol, zearalenone, and fumonisins is the rule instead of the exception. Another pattern is complacency after a clean test: feed from the same supplier may vary dramatically between harvests, and seasonal differences in weather alter toxin profiles. The [Risk assessment of the mycotoxin zearalenone](https://api.elsevier.com/content/abstract/scopus_id/0023411635) underscores that risk is dynamic and requires ongoing monitoring. ## Practical Monitoring Effective monitoring combines visual inspection, bulk sample collection, and quantitative analysis. Collect at least 5 to 10 subsamples from each batch of incoming grain or complete feed, mix thoroughly, and submit a composite sample to a certified laboratory. Use of enzyme-linked immunosorbent assay (ELISA) kits for on-farm screening is useful for rapid decisions but has higher false-positive and false-negative rates compared to high-performance liquid chromatography (HPLC) or liquid chromatography,tandem mass spectrometry (LC-MS/MS). [PubMed record 42382785](https://pubmed.ncbi.nlm.nih.gov/42382785/) and [PubMed record 42364855](https://pubmed.ncbi.nlm.nih.gov/42364855/) discuss tradeoffs between rapid tests and definitive quantification. Interpretation of laboratory results requires knowledge of the intended animal class: the same deoxynivalenol concentration that is tolerable in finishing pigs may be unacceptable in gestation diets. When results approach action levels, consult a [veterinary nutritionist](/blog/careers/becoming-a-veterinary-nutritionist-education-certification-and-practice) to refine risk assessment and decide on mitigation, such as blending with clean grain or increasing inclusion of mycotoxin binders. If clinical signs consistent with mycotoxicosis appear despite test results within accepted limits, explore water and feed additive sources and consider hepatic or reproductive histopathology for confirmation. Professional escalation to a diagnostic laboratory with expertise in mycotoxicology is warranted when outbreaks are severe or recurrent. ## Health Observation, Biosecurity, and Veterinary Escalation Monitoring swine health for signs of mycotoxicosis requires familiarity with toxin-specific clinical syndromes. Deoxynivalenol (vomitoxin) commonly causes feed refusal, reduced weight gain, and vomiting within hours of ingestion. Zearalenone produces estrogenic effects including vulvar swelling, mammary enlargement, and reproductive tract changes in prepubertal gilts, while breeding sows may exhibit anestrus or pseudopregnancy ([Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone](https://api.elsevier.com/content/abstract/scopus_id/33751251394)). Fumonisin B1 consumption leads to pulmonary edema and hydrothorax, a rapid-onset syndrome characterized by dyspnea, cyanosis, and death within days ([Pulmonary Edema and Hydrothorax in Swine Produced by Fumonisin B1](https://api.elsevier.com/content/abstract/scopus_id/0025461819)). Aflatoxins cause hepatotoxicity, icterus, and immune suppression, often presenting as poor performance and increased susceptibility to concurrent disease ([Merck Veterinary Manual](https://www.merckvetmanual.com/)). Producers and caretakers should observe daily feed intake, water consumption, and group behavior. Subtle reductions in growth rate or feed conversion efficiency may precede overt clinical signs. When multiple pens are affected with similar onset, feed contamination becomes a leading differential. Careful record keeping of batch numbers and feed delivery dates supports traceback investigations. Biosecurity measures reduce the risk of mold proliferation and cross-contamination. Store feed in clean, dry, well-ventilated bins, protect against moisture infiltration from leaks or condensation. Clean feed delivery equipment regularly, and maintain separate handling protocols for returned feed or damaged bags. Pest management (rodents, insects) prevents physical damage that allows fungal entry. These practices align with good manufacturing principles promoted by [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) and [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease). Diagnostic escalation begins when clinical signs are consistent with mycotoxicosis and other causes (infectious, nutritional, management) have been ruled out. Submit representative feed samples to an accredited laboratory for mycotoxin analysis, using validated methods such as high-performance liquid chromatography (HPLC) or enzyme-linked immunosorbent assay (ELISA). Interpret results cautiously: low mycotoxin concentrations do not guarantee absence of effect, particularly when multiple toxins occur together. Synergistic interactions, as documented between fumonisins and aflatoxins or between deoxynivalenol and zearalenone, can produce toxicity at levels far below individual advisory thresholds ([A review of worldwide contamination of cereal grains and animal feed with Fusarium mycotoxins](https://api.elsevier.com/content/abstract/scopus_id/0033620433)). Veterinarians should consult diagnostic laboratories for guidance on sample size, number of samples, and interpretation in the context of observed pathology. Uncertainty permeates mycotoxin risk management. Sampling error remains a major source of variability, a single feed sample may not represent an entire lot. Field conditions (temperature, humidity during storage) alter fungal growth and toxin production unpredictably. Subclinical effects, such as diminished immune response or reduced reproductive efficiency, may not be immediately apparent but cumulatively impair herd performance ([PubMed record 42382785](https://pubmed.ncbi.nlm.nih.gov/42382785/)). The absence of a confirmed outbreak does not imply absence of risk, especially in herds with fluctuating feed sources. Sustainability of swine production depends on minimizing waste and maintaining herd health. Effective mycotoxin management reduces feed discard, lowers veterinary costs, and improves feed conversion. Integration of toxin binders (e.g., aluminosilicates, yeast cell wall derivatives) under veterinary and nutritional guidance can mitigate absorption of certain mycotoxins, though efficacy varies by toxin ([Merck Veterinary Manual](https://www.merckvetmanual.com/)). Reliance on detoxification strategies should not replace rigorous ingredient sourcing and storage protocols. ## Frequently Asked Questions 1. **What are the first clinical signs of mycotoxin poisoning in growing pigs?** Reduced feed intake and slower growth are often the earliest indicators, sometimes accompanied by vomiting (deoxynivalenol), vulvar swelling (zearalenone), or respiratory distress (fumonisin). Producers should monitor daily feed consumption and weigh pigs at consistent intervals. 2. **Can mycotoxins be detected in feed visually or by smell?** No. Mold growth may be visible, but mycotoxins are chemically stable and can be present in feed that appears clean and smells normal. Laboratory analysis is required for reliable detection. 3. **How should feed samples be collected for mycotoxin testing?** Use a probe or grab samples from multiple locations within a batch (at least 10 subsamples per composite). Combine and mix thoroughly. Submit at least one kilogram to the laboratory. Follow guidelines from [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) for representative sampling. 4. **What is the role of the veterinarian when mycotoxins are suspected?** The veterinarian should perform a thorough clinical examination, review feed records, rule out infectious diseases, and coordinate proper sampling and laboratory submission. Interpretation of lab results in context of herd history and clinical signs is essential. 5. **Are some pigs more susceptible to mycotoxins?** Yes. Young animals, gestating or lactating sows, and pigs under concurrent stress (e.g., weaning, transport, disease) tend to show more severe effects. Breed differences are not well characterized in peer-reviewed sources. 6. **How long does it take for pigs to recover after contaminated feed is removed?** Recovery depends on toxin type, dose, duration of exposure, and individual pig condition. For acute fumonisin poisoning, mortality may occur rapidly. Chronic effects from deoxynivalenol or zearalenone often resolve within one to two weeks once clean feed is provided. 7. **Can mycotoxins affect pork quality or food safety?** Mycotoxins can accumulate in liver and kidney, but carryover into muscle tissue is generally low for most regulated toxins. However, strict feed management is required to comply with regulatory limits and protect consumer safety. 8. **What is the most important uncertainty in mycotoxin risk assessment?** The unpredictable occurrence of multiple mycotoxins in the same feed and their potential interactions. Current testing often measures individual toxins, but the combined effect may be additive or synergistic, making safe exposure thresholds difficult to establish. ## Educational Veterinary Notice Mycotoxin risk management in swine feed requires continuous vigilance from producers, nutritionists, and veterinarians. No single test or intervention eliminates all danger. Standardize sampling protocols, interpret laboratory results with professional judgment, and integrate health observations with feed records. When clinical signs suggest mycotoxicosis, escalate to your herd veterinarian for diagnostic workup and treatment recommendations. Proactive collaboration across the production team reduces economic losses and safeguards animal welfare. ## 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.