# Swine Vaccination Program Design and Records ## Key Takeaways - A robust swine vaccination program necessitates a comprehensive risk assessment, considering regional pathogen prevalence (e.g., PRRSV, PCV2, *M. hyopneumoniae*, Swine Influenza Virus), production type (farrow-to-finish vs. wean-to-finish), and biosecurity levels, as outlined by organizations like WOAH and USDA NAHMS. - Vaccine selection and scheduling must account for antigenic match to circulating strains, vaccine type (live attenuated vs. inactivated), route of administration (IM, oral), potential for maternal antibody interference, and the development window for active immunity, referencing resources like the Merck Veterinary Manual. - Strict adherence to cold chain integrity (maintaining 2-8°C for most inactivated vaccines, protecting from freezing and light) and proper administration techniques (correct needle size, hygiene, injection site) are paramount for vaccine efficacy, as emphasized by FAO guidelines. - Meticulous record-keeping is critical, capturing vaccine product identity, batch number, storage conditions, administration date, dose, route, individual animal identification, and subsequent health outcomes to enable periodic program review, audit, and adjustment based on serological monitoring and disease incidence. - Vaccination efficacy is influenced by host nutritional status, with deficiencies in energy, protein, vitamin E, and selenium impairing immune responses, necessitating balanced rations and ad libitum access to clean water prior to and following vaccination. - Common vaccination failures stem from factors including expired or improperly stored vaccines, incorrect dosage or route, immunosuppression from concurrent disease or mycotoxins, high maternal antibody interference, or overwhelming pathogen challenge, requiring diagnostic confirmation and veterinary escalation. --- A systematic swine vaccination program integrates herd health planning, cold chain integrity, administration technique, and record keeping to achieve predictable immunity and measurable disease reduction. Program design begins with risk assessment of circulating pathogens, production stage needs, and regulatory requirements, then proceeds to vaccine selection, scheduling, and delivery protocols. Records must capture product identity, batch number, storage conditions, timing, individual animal identification, and subsequent health outcomes to enable periodic program review and adjustment. ## At a Glance | Component | Key Considerations | Documentation | |--------|---------|--------| | Herd health planning | Disease prevalence (regional, farm), production type (farrow-to-finish, wean-to-finish), biosecurity level, regulatory requirements ([WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/)) | Farm disease history, risk assessment, vaccination objectives | | Vaccine selection and schedule | Antigen match, live attenuated vs inactivated, route (IM, oral), maternal antibody interference, interval between doses, multivalent compatibility ([Merck Veterinary Manual](https://www.merckvetmanual.com/)) | Product label, manufacturer recommendations, veterinarian protocol | | Cold chain and handling | Temperature range (2,8°C for most inactivated vaccines), freeze protection, reconstitution timing, light sensitivity, diluent compatibility ([FAO Animal Production and Health](https://www.fao.org/animal-production/en/)) | Daily temperature logs, storage equipment calibration records | | Administration and records | Individual/penned identification, dose verification, needle size and hygiene, injection site, date, vaccinator ID ([USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease)) | Vaccination ledger, batch numbers, adverse event reports | | Outcomes and review | Serological monitoring (antibody titers, population immunity), disease incidence, clinical protection, program audit ([USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms)) | Laboratory reports, health records, annual program evaluation | ## System Context for Herd Health Planning Vaccination program design must account for the epidemiological context of the farm. Endemic pathogens such as [porcine reproductive and respiratory syndrome](/knowledge/viruses/general/porcine-reproductive-and-respiratory-syndrome-genomic-surveillance-and-vaccine-strategies-using-bioinformatics) virus, porcine circovirus type 2, [Mycoplasma hyopneumoniae](/knowledge/bacteria/livestock-bacteria/mycoplasma-hyopneumoniae-enzootic-pneumonia-pigs), and [swine influenza](/knowledge/veterinary-medicine/clinical-methods/swine-swine-influenza-diagnosis-management) virus vary in regional prevalence and strain composition. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides baseline data on pathogen circulation in U.S. swine herds, while [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) outlines disease notification and control standards for transboundary infections such as classical swine fever. Programs aimed at eradication, such as the Peruvian classical swine fever vaccination effort, require high coverage and coordinated timing across production units ([Evaluation of the impact of live pig trade network, vaccination coverage and socio-economic factors in the classical swine fever eradication program in Peru](https://www.semanticscholar.org/paper/cdd01e0e2d0c0b76b1e0be469bfcbcb96ade5620)). Production type determines the immune status of replacement animals, sow longevity, and pig flow. Farrow-to-finish operations must vaccinate sows prebreeding and prefarrowing to maximize maternal antibody transfer, while wean-to-finish sites rely on purchased stock with unknown exposure history. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) emphasizes that vaccination schedules should be tailored to the window of susceptibility for each pathogen, accounting for maternal antibody interference and the time required for active immunity development. Risk factors such as stocking density, all-in-all-out versus continuous flow, and proximity to infected herds also shape program intensity. ## Planning Decisions in Vaccine Selection and Schedule Vaccine selection balances antigenic homology to field strains, safety profile, and route of administration. Live attenuated vaccines (e.g., modified-live classical swine fever vaccines used in Japan and Peru) generally induce broader and longer-lasting immunity than inactivated products but carry a risk of reversion to virulence in immunocompromised animals ([Pig farm vaccination against classical swine fever reduces the risk of transmission from wild boar](https://www.semanticscholar.org/paper/7c618d4db3bbe448eb69c337875e43c4b01d5097)). Oral vaccination, employed for wild boar control of classical swine fever, provides practical coverage of inaccessible populations but requires bait stability and consumption monitoring ([Efficient oral vaccination program against classical swine fever in wild boar population](https://www.semanticscholar.org/paper/7ca2fe7861c06fae65e9f32421fa562b6c35c4d7)). Schedule design must consider interval between priming and booster doses, as well as timing relative to farrowing, weaning, and movement. Research on programming antibody responses shows that innate immune activation at the time of immunization can influence the magnitude and persistence of the adaptive response ([Programming the magnitude and persistence of antibody responses with innate immunity](https://api.elsevier.com/content/abstract/scopus_id/79952173864)). This implies that adjuvant selection and concurrent treatments should be deliberate. In practice, the [Merck Veterinary Manual](https://www.merckvetmanual.com/) advises that killed vaccines often require two initial doses 2,4 weeks apart, followed by boosters at intervals dictated by disease risk and serological monitoring. ## Core Management Framework for Administration and Records Cold chain management is the foundation of vaccine efficacy. Vaccines must be stored at the manufacturer-specified temperature, usually 2,8°C, protected from freezing and light exposure. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) guidelines recommend daily temperature monitoring of refrigerators used for vaccine storage, with backup alarms and emergency plans for power loss. Reconstituted vaccines must be used within the time window stated on the label, typically 1,2 hours, and any unused product discarded. Administration technique directly affects immune response. Needle gauge and length must match pig size and injection site (intramuscular in the neck, avoiding the ham). The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) resources emphasize needle hygiene to prevent abscess formation and disease transmission. Individual animal identification (ear tag, tattoo, or electronic ID) should be recorded alongside vaccine product, batch number, dose, date, and vaccinator. Paper or electronic record systems must be designed for easy retrieval during health audits or outbreak investigations. Outcome measures include seroconversion rates, reduction in clinical disease, and improvement in production parameters such as mortality and average daily gain. Periodic review,annually or after each production cycle,allows adjustment of vaccine selection, timing, or route based on surveillance data. Programs that lack structured review risk continued use of suboptimal vaccines or schedules, as documented in the Peruvian classical swine fever program where vaccination coverage alone did not eliminate virus circulation without attention to pig trade network and socioeconomic constraints ([Evaluation of the impact of live pig trade network, vaccination coverage and socio-economic factors in the classical swine fever eradication program in Peru](https://www.semanticscholar.org/paper/cdd01e0e2d0c0b76b1e0be469bfcbcb96ade5620)). Professional escalation is warranted when program review reveals persistent disease despite correct administration, unexpected adverse events, or evidence of vaccine failure. Veterinary consultation and [laboratory investigation](/knowledge/diagnostics/molecular/laboratory-investigation) into antigenic match, cold chain breaches, or immunosuppressive comorbidities are then required. ## Facilities, Environment, and Cold Chain Management Proper vaccine handling begins with storage and transport. Refrigerated equipment must maintain a temperature range specified by each product’s label, typically 2,8 degrees Celsius, and be equipped with continuous monitoring devices (see [Merck Veterinary Manual](https://www.merckvetmanual.com/) for cold chain guidelines). Facilities should have backup power for vaccine refrigerators and separate units for diluents and biologics. On-farm vaccine preparation areas need adequate lighting, clean surfaces, and immediate access to ice packs or coolers for field administration. The [FAO Animal Production and Health resources](https://www.fao.org/animal-production/en/) emphasize that temperature excursions, even brief ones, can denature antigens and cause vaccine failure without visible changes. Environmental conditions during administration affect vaccine stability. Direct sunlight, heat, and freezing degrade modified-live products. Operators must use insulated carriers when moving vaccines through barns and avoid exposing reconstituted biologics to temperatures above 25 degrees Celsius for more than one hour. Cleaning and disinfection of syringes and needles between groups is mandatory to prevent iatrogenic disease transmission, as outlined in the [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) for biosecurity practices. ## Nutrition and Water Interactions Vaccine immunogenicity depends on the nutritional status of the pig. Inadequate energy, protein, or specific micronutrients such as vitamin E and selenium impair T-cell responses and antibody production. While controlled trials on nutritional modulation of vaccine response are limited in swine, the relationship between metabolic status and immune competence is well established (see [PubMed record 42430997](https://pubmed.ncbi.nlm.nih.gov/42430997/) for discussion of host factors in vaccination). Farms should provide balanced rations and clean water ad libitum before and after vaccination events. Stress from feed withdrawal or water deprivation on processing days should be minimized. For oral vaccines,used in some classical swine fever (CSF) programs for wild boar,bait formulation and palatability directly influence ingestion rates. Studies from Japan’s Gifu Prefecture oral vaccination program (see [Efficient oral vaccination program against classical swine fever in wild boar population](https://www.semanticscholar.org/paper/7ca2fe7861c06fae65e9f32421fa562b6c35c4d7)) indicate that seasonal factors such as food availability affect bait uptake. In domestic pigs, oral vaccines must be mixed with feed or water in a manner that ensures each pig consumes a sufficient dose, requiring careful calculation of daily intake and temporary feed withdrawal to synchronize consumption. ## Production-Stage Vaccination Decisions Protocols differ by age and reproductive status. Gilts and sows require booster vaccinations against diseases such as porcine circovirus type 2 or leptospirosis at specified intervals before breeding and before farrowing. The [USDA NAHMS](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides survey data on common vaccination practices across U.S. herds. Piglets often receive maternally derived antibodies from colostrum, but those antibodies can interfere with live vaccines if given too early. Timing of first dose must account for passive immunity decay, which varies by antigen and litter. Weaners and growers receive booster vaccines based on the farm’s risk profile for respiratory and enteric pathogens. Finisher vaccines, if used, must respect withdrawal intervals for slaughter. Decisions regarding vaccine type,modified-live, killed, or vector-based,depend on desired duration of immunity, disease prevalence, and concurrent health issues. Veterinary professionals should design production-stage calendars, as the [Merck Veterinary Manual](https://www.merckvetmanual.com/) notes that off-label timing can reduce efficacy or increase adverse reactions. No universal schedule applies, each herd program requires risk assessment. ## Records as the Foundation of Review Complete vaccination records include: batch and serial numbers of each vaccine, date of administration, route (intramuscular, intradermal, oral), dose volume, location of injection, identity or group of pigs treated, person administering, and any observed adverse reactions. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) requires traceable records for disease control programs, and the [USDA APHIS](https://www.aphis.usda.gov/livestock-poultry-disease) mandates documentation for certain federally regulated vaccines. Electronic herd-health software can link vaccination data to production outcomes such as mortality, average daily gain, and treatment rates. Records enable outcome evaluation. Comparing serological titers or disease incidence before and after a vaccine change helps quantify efficacy. For example, a study on CSF vaccination in Peru (see [Evaluation of the impact of live pig trade network, vaccination coverage and socio-economic factors](https://www.semanticscholar.org/paper/cdd01e0e2d0c0b76b1e0be469bfcbcb96ade5620)) showed that incomplete records and variable coverage contributed to persistent disease. Regular review of vaccination records against health events allows detection of failures. ## Welfare During Vaccine Administration Restraint methods must minimize pain and stress. Proper handling reduces struggling, which can cause tissue trauma and needle breakage. Training stockpeople in low-stress techniques is essential. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) includes guidelines for safe injection sites,typically the neck triangle,to avoid carcass blemishes and sciatic nerve damage. Needles should be changed every 10 to 20 pigs to prevent abscess formation and cross-contamination. Adverse vaccine reactions, although rare, require documentation and reporting. Anaphylaxis or injection-site granulomas affect animal welfare and production value. Veterinary oversight is needed when reactions cluster, as product lot defects or improper handling may be responsible. ## Worker and Food Safety Needle-stick injuries are the primary occupational hazard in vaccination programs. Workers should use needle guards, avoid recapping, and receive training on immediate first aid. Vaccination of personnel against zoonotic pathogens such as swine influenza virus or leptospirosis is advisable in high-risk settings. The [USDA APHIS](https://www.aphis.usda.gov/livestock-poultry-disease) site offers resources on zoonotic disease prevention. Food safety involves respecting withdrawal periods for vaccines labeled with slaughter intervals. Modified-live vaccines are generally safe, but some adjuvanted products cause injection-site lesions that must be trimmed at slaughter. Records of vaccine serial numbers and slaughter dates enable traceability if residues or lesions appear in the packing plant. ## Common Failure Patterns and Their Detection Vaccination program failures are multifactorial. Causes include: expired or improperly stored vaccine, incorrect dose or route, immunosuppression from concurrent disease or mycotoxin exposure, high maternal antibody interference, and overwhelming challenge pressure from a novel or heterologous strain. The [PubMed record 42438383](https://pubmed.ncbi.nlm.nih.gov/42438383/) likely discusses such variables in the context of CSF vaccination, similar principles apply across diseases. In the Japan CSF outbreak (see [Pig farm vaccination against classical swine fever reduces the risk of transmission](https://www.semanticscholar.org/paper/7c618d4db3bbe448eb69c337875e43c4b01d5097)), farm vaccination reduced but did not eliminate transmission, underscoring that coverage alone is insufficient without biosecurity. Failure patterns often appear as disease in vaccinated cohorts. Investigating seroconversion rates using ELISA or [virus neutralization assays](/blog/guides/virus-neutralization-assays-choosing-a-format-and-interpreting-readouts) can identify gaps. The [USDA NAHMS](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides baseline data for comparing herd performance. ## Practical Monitoring Strategies Routine serological monitoring of sentinel pigs, such as those vaccinated at a known age, tracks population antibody levels. Interpreting titers requires knowledge of assay threshold and vaccination history. Autogenous vaccines, used for farm-specific strains, demand even closer outcome monitoring. The [PubMed record 42417000](https://pubmed.ncbi.nlm.nih.gov/42417000/) may address immune response variability. Genetic markers influencing vaccine response have been studied (see [Elucidation of novel SNPs affecting immune response to classical swine fever vaccination](https://www.semanticscholar.org/paper/00af6c146fbd93116e5697544fb5bf95c1d5ce6e)), but routine genetic testing is not yet standard. Practical monitoring also includes checking vaccination technique through direct observation. Standard operating procedures should be reviewed annually and revised when new vaccines or pathogens emerge. Escalation to a veterinary specialist is indicated when mortality or morbidity exceeds baseline despite proper protocol adherence, or when unusual adverse events occur. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) encourages reporting vaccine failures as part of disease surveillance systems. ## Health Observation and Monitoring After Vaccination Systematic observation of pigs following vaccination serves as a primary mechanism for detecting adverse events and assessing herd-level response. Farm personnel should be trained to recognize immediate reactions such as anaphylaxis, injection site swelling, or lethargy within the first 30 minutes after administration. The Merck Veterinary Manual recommends recording any abnormal behavior, respiratory distress, or local inflammation that persists beyond 24 hours. Observation should extend to the production stage, including feed intake, growth rate, and mortality patterns in vaccinated cohorts. The USDA National Animal Health Monitoring System emphasizes that passive surveillance through daily pen checks must be supplemented with active monitoring during scheduled health rounds, especially within the first week post-vaccination. ## Biosecurity During Vaccine Administration Vaccination events create biosecurity risks that require mitigation through strict protocols. Needles, syringes, and multidose vials serve as mechanical vectors for blood-borne pathogens such as porcine reproductive and respiratory syndrome virus and porcine circovirus type 2. The WOAH Terrestrial Animal Health Code advises that single-use needles should be used per animal and changed between pens. Vaccine preparation should occur in a clean, dedicated area separate from animal housing. Personnel must change gloves and disinfect boots between barns or age groups. Oral vaccination programs, as described in the study on classical swine fever elimination in wild boar populations, require bait placement strategies that minimize contact with non-target species and environmental contamination. Biosecurity also extends to vaccine storage. Refrigerators and freezers used for cold chain maintenance should be monitored with calibrated thermometers and alarmed systems to alert staff to temperature excursions. ## Diagnostic Confirmation and Veterinary Escalation Vaccination failure, defined as the occurrence of clinical disease in adequately vaccinated animals, necessitates diagnostic investigation to determine causative factors. The FAO Animal Production and Health guidelines recommend collecting paired serum samples from acute and convalescent phases to evaluate seroconversion. Tissue samples from affected pigs should be submitted for [polymerase chain reaction](/knowledge/molecular-biology/polymerase-chain-reaction) testing or virus isolation to confirm pathogen presence. Veterinary escalation is required when more than 2% of a vaccinated group exhibits clinical signs consistent with the target disease, when vaccine-associated adverse events occur at rates exceeding those reported by the manufacturer, or when serological monitoring reveals inadequate population immunity. The study evaluating the impact of live pig trade networks on classical swine fever eradication in Peru demonstrates that diagnostic data should be integrated with vaccination records and movement patterns to identify transmission hotspots. ## Uncertainty in Vaccination Programs Vaccination efficacy is not absolute and depends on host factors, pathogen strain variation, and management conditions. Immunogenomic research published in 2023 using pigs vaccinated against classical swine fever identified novel single nucleotide polymorphisms that influence immune response variability among individual animals. This genetic heterogeneity means that some pigs within a uniformly vaccinated herd may not develop protective immunity. Furthermore, the persistence of maternal antibodies can interfere with vaccine take in young pigs, creating windows of susceptibility. The 2011 study on programming antibody responses through [innate immunity](/knowledge/veterinary-medicine/veterinary-pathology-microbiology/innate-immunity-receptors-and-effector-mechanisms) highlights that vaccine formulation, adjuvant selection, and dosing interval modulate the magnitude and duration of protection. Practitioners must acknowledge that vaccination alone cannot compensate for poor nutrition, concurrent disease, or high pathogen challenge pressure. Regular serological profiling and risk assessment are required to adjust programs iteratively. ## Sustainability of Vaccination Programs Long-term sustainability of swine vaccination programs depends on economic viability, logistical feasibility, and continuous improvement. The cost benefit analysis should account for vaccine purchase, labor for administration, cold chain maintenance, and diagnostic monitoring against reductions in mortality, treatment costs, and production losses. The 2015 reflection on the 1976 swine influenza immunization program in New York City illustrates that public health campaigns require robust surveillance systems to detect rare adverse events and maintain stakeholder confidence. On farm, sustainability involves integrating vaccination into routine health management instead of treating it as a stand alone intervention. The 2021 study on classical swine fever vaccination reducing transmission risk from wild boars in Japan demonstrates that strategic vaccination of domestic pigs can lower region wide disease pressure, benefiting both farm and neighboring populations. Records must be reviewed annually by the herd veterinarian to adjust antigen selection, timing, and coverage based on farm specific risk factors and emerging disease threats. ## Frequently Asked Questions **1. How soon after vaccination can I expect to see protection?** Protective immunity typically develops 7 to 21 days after the final dose, depending on vaccine type, antigen formulation, and pig age. Modified live vaccines usually induce immunity faster than killed products. **2. Can I vaccinate pregnant sows?** Many vaccines are labeled safe for use in pregnant sows, but you must verify with the manufacturer. Vaccination against [porcine parvovirus](/knowledge/viruses/livestock-viruses/porcine-parvovirus) and Escherichia coli is often recommended during gestation to protect neonates through colostral immunity. **3. What should I do if a pig has a severe reaction to vaccination?** Immediately remove the pig from the group, provide supportive care including antihistamines or epinephrine as prescribed by your veterinarian, and report the event to the manufacturer and your veterinarian for documentation. **4. How often should I replace needles during vaccination?** Needles should be changed between every 10 to 15 pigs to reduce dulling and prevent cross contamination. Never reuse a needle that has touched an obviously ill animal. **5. Can I mix different vaccines in the same syringe?** Mixing vaccines is not recommended unless explicitly stated on the product label. Incompatible adjuvants or preservatives may inactivate antigens or cause unintended adverse reactions. **6. What records are essential for a vaccination program?** Records must include vaccine batch number, expiration date, dose volume, route, date and time of administration, pig identification (individual or group), and any observed adverse events. Maintain records for at least three years. **7. How do I handle a vaccine that was left out of refrigeration?** Do not use the vaccine. If the temperature excursion exceeded product stability data, discard the vaccine. Use a data logger to confirm temperature history. Consult the manufacturer if you are uncertain. **8. Can I vaccinate pigs that are already incubating disease?** Vaccinating animals in the incubation period may not prevent disease and could worsen clinical signs. Separate sick pigs from the healthy group and postpone vaccination until they are recovered. *This article is for educational purposes and does not replace individualized veterinary advice. Swine vaccination programs should be designed and supervised by a licensed veterinarian who is familiar with the farm’s health status, disease risk profile, and regulatory requirements. Always follow vaccine label instructions and national animal health regulations.* ## 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.