# Fresh Cow Monitoring in the First 21 Days ## Key Takeaways - The first 21 days postpartum represent a critical high-risk window for dairy cows, characterized by suppressed immune function and increased susceptibility to metabolic disorders (hypocalcemia, ketosis) and infectious diseases (metritis, mastitis). Early detection and intervention are paramount for mitigating these risks and improving production outcomes. - A structured daily monitoring system focusing on appetite, rumen fill, manure consistency, rectal temperature (especially in the first 3-5 days), udder health, locomotion, demeanor, and vaginal discharge is essential for identifying deviations from normal. Escalation triggers, such as reduced intake for two consecutive feedings or a temperature >39.5°C, necessitate prompt action. - Physiological rationale for close monitoring includes the rapid metabolic shifts from gestation to lactation, leading to negative energy balance and impaired immune responses. Subclinical hypocalcemia and hyperketonemia directly impact motility and increase risks for retained placenta and metritis, respectively. - Effective monitoring requires trained personnel, consistent observation timing (ideally before feed delivery), and appropriate data recording platforms (electronic software is preferred for trend analysis). Facilities must support individual visibility, adequate feeding space (0.6-0.9m/cow), and clean bedding to prevent disease transmission. - Escalation pathways with clear criteria for veterinary referral are crucial. Conditions like fever >40.0°C, complete anorexia, recumbency, or abnormal breathing demand immediate professional assessment, while less severe, persistent abnormalities also warrant veterinary consultation. - Nutritional management, particularly ensuring immediate access to palatable, high-fiber diets and unrestricted water, is foundational. Reductions in feeding duration and meal frequency, observable daily, can precede clinical signs of metritis and mastitis by 24-48 hours, serving as an early warning. --- The first 21 days after calving represent the period of highest metabolic and infectious disease risk in dairy cattle. A structured daily monitoring system, paired with clear escalation criteria, is the foundation for early intervention and improved transition cow outcomes. This article describes a systematic daily observation and escalation framework designed for the early-lactation period. ## At a Glance | Parameter | Observation Frequency | Normal vs Abnormal | Escalation Trigger | |-----------|----------------------|-------------------|-------------------| | Appetite and feed intake | Each feeding (at least twice daily) | Vigorous eating, abnormal if off-feed, sorting, or slow consumption | Reduced intake below individual baseline for two consecutive feedings | | Rumen fill and manure consistency | Once daily (morning) | Left flank moderate fill, manure semi-formed, abnormal if scours, pasty, or scant | Marked change in consistency or absence of manure | | Rectal temperature | Once daily (first 3,5 days, then as indicated) | 38.3,39.4°C, abnormal if >39.5°C or <38.0°C | Temperature outside range on first check or persisting despite supportive care | | Udder and milk | Each milking | Symmetrical, warm without hardness, milk normal color and consistency | Heat, swelling, or abnormal secretion (clots, watery, blood) | | Locomotion and demeanor | Twice daily (observation during movement) | Alert, walking freely, abnormal if depressed, head down, separation from group, or lameness | Reluctance to stand, severe depression, or obvious lameness (score ≥3) | | Vaginal discharge | Once daily (for first 10 days) | Normal lochial discharge (reddish-brown to colorless, decreasing over time) | Foul odor, purulent discharge, or retained fetal membranes beyond 24 hours | ## System Context and Physiological Rationale ### The High,Risk Window The transition from gestation to lactation imposes rapid physiological and metabolic adjustments. Hypocalcemia, ketosis, retained placenta, metritis, and left displaced abomasum cluster in the first three weeks postpartum (__MASK_1__). The first 21 days also correspond to the period when immune function is suppressed, making cows susceptible to environmental pathogens. The __MASK_2__ reports that subclinical and clinical disease during this interval reduces peak milk yield and increases culling risk. ### Key Pathophysiologies - **Subclinical hypocalcemia** impairs rumen and uterine motility, contributing to displaced abomasum and retained placenta. - **Hyperketonemia** results from negative energy balance and is associated with reduced dry matter intake and increased risk of metritis. - **Metritis** typically presents within the first 10,14 days, behavioral changes such as reduced feeding time and lower intake can precede clinical signs by 1,2 days (__MASK_3__). - **Mastitis** from environmental organisms often appears in the first weeks due to teat end damage and compromised immunity. Monitoring systems must account for the fact that clinical signs may be subtle and that many disorders present concurrently. Professional oversight from a herd veterinarian is necessary to interpret patterns and adjust protocols when recurrence rates exceed established benchmarks (__MASK_4__). ## Planning Decisions for Daily Observation Systems ### Personnel and Training Daily monitoring should be performed by individuals who can identify deviations from normal cow behavior and physical condition. Paraprofessionals such as herd health technicians or senior stockpersons require training in standardized observation techniques. The __MASK_5__ emphasizes that effective surveillance depends on consistent criteria and clear communication between observers and the attending veterinarian. Cross,training multiple staff members reduces gaps during absences. ### Timing and Environment Observations are most informative when conducted at the same time each day, under consistent lighting, and before feed delivery to maximize opportunity to see feeding behavior. The relationship between feeding space and social competition is well documented: cows with inadequate bunk space show increased aggression and reduced intake (__MASK_6__). Therefore, monitoring systems must consider stocking density and design as confounders when interpreting abnormal behavior. ### Data Recording Platforms Paper logs can suffice for small herds, but electronic herd management software allows trend analysis and alerts for individuals that deviate from their own baseline. Automated monitoring tools (rumination collars, activity monitors, milk yield sensors) can supplement visual observation but do not replace it. The evidence base for automated detection of disorders continues to grow (__MASK_7__), yet visual appraisal remains the gold standard for conditions such as vaginal discharge or udder asymmetry. Uncertainty exists regarding the sensitivity of automated systems across different housing types and climates, consulting with the herd veterinarian is advisable before committing to a specific technology platform. ## Core Management Framework for Daily Monitoring ### Morning Observation Protocol Begin with a walk through the fresh cow pen before feed delivery. Assess rumen fill (scale of 1,5, with 2,3 being target for fresh cows), check for abdominal distension (left vs right side), and note any cow that is slow to rise or remains lying when approached. Record individual body condition score changes (loss >0.5 points in 21 days warrants investigation). Take rectal temperatures for the first 3,5 days, extending to 7 days if the herd has a history of high metritis incidence. Temperature deviation from the herd baseline (>39.5°C) should prompt a complete physical examination by trained personnel. ### Afternoon and Evening Checks At milking, evaluate udder symmetry, palpate for heat or edema, and examine foremilk for clots or discoloration. Observe cow level of alertness and willingness to enter the parlor. Any cow that is depressed, isolate from groupmates, or shows a drop in milk yield greater than 10% from the previous day merits a closer look. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) guidance recommends a low threshold for separating suspect animals for individual examination to prevent disease spread. ### Escalation Pathways and Professional Oversight A tiered escalation system ensures that mild abnormalities are managed at the farm level while serious conditions are referred immediately. For example, a cow with a single elevated temperature but normal appetite may be monitored for 12 hours, a cow with fever and foul vaginal discharge warrants immediate veterinary examination. Escalation criteria should be written and reviewed quarterly with the herd veterinarian. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) advises that treatment protocols must be established in advance, clearly distinguishing where on,farm intervention ends and professional involvement begins. Documentation of all escalations, outcomes, and delays in response provides data to refine the system and identify training needs. ## Facilities and Environment for Fresh Cow Observation The transition pen environment directly influences the ability to detect disease and the cow’s recovery trajectory. Fresh cows require low stocking density, ample lying space, and easy access to feed and water. Overcrowding reduces feeding time and increases competitive interactions, both of which are associated with higher rates of subclinical ketosis and metritis. [Effect of feeding space on the inter-cow distance, aggression, and feeding behavior of free-stall housed lactating dairy cows](https://api.elsevier.com/content/abstract/scopus_id/3142647638) documents that inadequate feeding space decreases inter-cow distance and increases aggressive displacements, reducing dry matter intake (DMI) during the critical postpartum period. For monitoring systems to function, each cow must be individually visible from a routine observation path. Pens should be designed with consistent lighting and non-slip flooring to facilitate safe examination of the perineum, udder, and locomotion. Bedding management must prioritize cleanliness, wet or soiled stalls increase the risk of environmental mastitis and uterine infection. [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) provisions on animal welfare emphasize that housing must permit normal resting and feeding behavior, both of which are compromised in dirty or overcrowded transition pens. ## Nutrition and Water in the First 21 Days Nutritional monitoring begins with verification that the fresh cow has immediate access to a palatable, high-fiber diet immediately after calving. A negative energy balance is physiological, but extreme deficits precipitate hyperketonemia, fatty liver, and immunosuppression. Daily monitoring of feed intake is one of the most sensitive indicators of impending disease. [Changes in feeding behavior as possible indicators for the automatic monitoring of health disorders in dairy cows](https://api.elsevier.com/content/abstract/scopus_id/40649096371) demonstrates that reductions in feeding duration and meal frequency precede clinical signs of metritis and mastitis by 24 to 48 hours. Therefore, a practical monitoring system includes checking the amount of residual feed at the same time each day. Water availability must be unrestricted: a fresh cow consumes 30 to 50 percent more water than a dry cow, and dehydration compounds hypocalcemia and reduces rumen motility. Water troughs should be cleaned daily and located within 5 m of the feed bunk. For cows receiving propylene glycol or calcium boluses, monitoring for voluntary consumption versus refusal provides an early clue to severity of illness. ## Production-Stage Decisions and Monitoring Frequency The first 21 days encompass three overlapping physiological phases: immediate post-calving (day 1,3), transition to peak milk (day 4,14), and establishment of persistent lactation (day 15,21). Monitoring intensity should be highest during the first week. A structured checklist at each milking or at a fixed time (e.g., after morning feeding) captures the four essential parameters: attitude, appetite, manure consistency, and temperature. [Prepartum behavior and dry matter intake identify dairy cows at risk for metritis](https://api.elsevier.com/content/abstract/scopus_id/35748961394) shows that cows with low prepartum DMI and altered lying behavior have a markedly higher risk of metritis postpartum. This finding underscores that monitoring can begin before calving. For the first 10 days, rectal temperature should be recorded daily. Any cow with a temperature ≥ 39.5 °C should be rechecked and examined for metritis, mastitis, pneumonia, or other infections. After day 10, temperature monitoring can be reduced to every other day unless clinical signs arise. Records must be kept individually and reviewed daily by the herd manager or veterinarian to identify trends. ## Records and Electronic Monitoring A written or electronic log for each fresh cow is the backbone of an escalation system. The log should include calving date, parity, calving ease score, colostrum intake, daily rectal temperature, feed intake score, and any treatments administered. [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides baseline data on disease incidence in U.S. dairy herds, these benchmarks allow producers to compare their fresh-cow morbidity rates against national averages. Automated monitoring systems (e.g., rumination collars, activity meters, milk yield sensors) can supplement visual observation but do not replace it. When electronic alerts trigger, the cow must be examined manually before any treatment decision. The risk of false positives and false negatives from automated systems is well documented, visual confirmation remains the gold standard for clinical diagnosis. ## Welfare Considerations and Pain Assessment Fresh cows experience acute pain from dystocia, uterine involution, and teat edema. Effective monitoring includes recognition of pain beyond overt lameness. Behaviors such as teeth grinding, vocalization, or failure to lie down in a normal sternal position indicate distress. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) stipulates that painful procedures (e.g., tail docking, dehorning) must be avoided in transition cows unless medically necessary. In the first 21 days, any surgical intervention (e.g., correction of displaced abomasum) should be accompanied by appropriate analgesia. Monitoring protocols must also assess udder congestion and teat damage, if a cow repeatedly stamps or kicks during milking, she may be experiencing acute mastitis or injury. Early detection of welfare problems reduces the duration of suffering and improves the likelihood of a full recovery. ## Worker Safety and [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Fresh cow monitoring involves close contact with animals that may be in pain or aggressive due to hypocalcemia or ketosis. Workers must be trained in safe handling: use of head gates, the “flight zone” concept, and proper restraint for rectal examination. [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) guidelines emphasize biosecurity protocols to prevent contamination of the fresh-cow pen with pathogens from other groups. Food safety concerns center on antibiotic residues and [somatic cell](/blog/guides/somatic-cell) counts. Any cow treated with antimicrobials must be identified with a leg band or tail tape, and her milk withheld until label withdrawal periods are met. Milk from fresh cows should be tested for antibiotics before it enters the bulk tank, as the first 21 days account for a disproportionate number of violative residues. Daily monitoring for clinical mastitis allows early culture and treatment, reducing the volume of milk discarded and preventing pathogen spread. ## Failure Patterns and Common Disorders The most frequent fresh-cow failures within the first 21 days are retained placenta, metritis, clinical ketosis, displaced abomasum (DA), and hypocalcemia. These conditions often interact: a cow with retained placenta is five times more likely to develop metritis, a cow with ketosis has an increased risk of left DA. [Merck Veterinary Manual](https://www.merckvetmanual.com/) sections on metabolic and reproductive diseases provide detailed descriptions of clinical signs. In a well-monitored herd, the pattern of disease emergence tells a story about management. For example, an outbreak of clinical ketosis on days 5,10 suggests inadequate energy density in the postpartum diet, whereas a cluster of metritis cases on days 3,7 indicates possible contamination of the calving pen or poor obstetrical hygiene. Failure to monitor daily allows small problems to cascade: subclinical hypocalcemia on day 1 leads to poor rumen motility and reduced DMI, which predisposes to ketosis on day 4, which further depresses immune function and leads to metritis on day 7. The monitoring system must detect these links early. ## Practical Monitoring Protocol Steps A usable daily protocol should be posted in the parlor or fresh pen. The steps are: 1. Observe cow from a distance: posture, ear position, rumen fill, and separation from group. 2. Approach and assess appetite by looking at the feed bunk and oral mucous membranes (color, moisture). 3. Check for abnormal discharges: vulvar discharge should be assessed for odor and color, a brownish, fetid discharge indicates metritis. 4. Auscultate the rumen for motility (contractions per minute). Silent rumen is an emergency. 5. Palpate the left flank for a ping indicative of left displaced abomasum, if present, refer to veterinarian immediately. 6. Check udder for heat, swelling, or discoloration. 7. Record rectal temperature each morning for the first 10 days. 8. Score manure: loose, watery manure may indicate acidosis or infection, dry, scant manure may indicate dehydration or intestinal obstruction. [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) guidelines recommend that any cow showing two or more abnormalities in the checklist be examined by a veterinarian within 4 hours. A single abnormality (e.g., temperature > 39.5 °C without other signs) can be rechecked after 6 hours, if persistent, escalate. ## Escalation Criteria and Professional Referral The monitoring system must have clear thresholds for escalating beyond the farm staff. Cows with rectal temperature ≥ 40.0 °C, complete anorexia, recumbency, abnormal breathing, or bloody manure require immediate veterinary attention. Conditions that do not improve within 12 hours of supportive therapy (e.g., calcium bolus, propylene glycol drench) should also be referred. [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) alerts practitioners to report any unusual mortality clusters to state animal health authorities, as fresh-cow deaths can signal infectious disease outbreaks or toxicity. The escalation pathway should be documented in the herd health plan and reviewed annually. By linking daily observation to a structured escalation framework, the first 21 days become a period of active management instead of passive waiting,reducing morbidity, improving milk yield, and enhancing cow welfare. ### Health Observation, Biosecurity, and Veterinary Escalation in the Early Lactation Period Daily health observation of fresh cows must extend beyond visual appraisal to include systematic measurement of rumination time, feed intake, and rumen fill. Changes in feeding behavior, such as reduced meal frequency or duration, can precede clinical disease by 24 to 48 hours and may serve as early indicators for automated monitoring of health disorders in dairy cows (Changes in feeding behavior as possible indicators for the automatic monitoring of health disorders in dairy cows). Such behavioral shifts are associated with increased risk of metritis, and reduced prepartum dry matter intake and altered feeding patterns have been specifically linked to uterine infection (Prepartum behavior and dry matter intake identify dairy cows at risk for metritis). Therefore, daily recording of feed consumption and rumen fill score (on a 1 to 5 scale) is recommended. Rectal temperature should be taken for any cow that appears dull, has reduced feed intake, or shows abnormal behavior, but routine temperature taking of all fresh cows without indication is not evidence-based for disease prevention. Biosecurity measures during the early lactation period focus on preventing environmental contamination and limiting pathogen transfer among high-risk animals. Fresh cows are immunocompromised and more susceptible to bacterial and viral pathogens. The World Organisation for Animal Health (WOAH) Terrestrial Animal Health Code provides general principles for biosecurity in dairy operations, including separation of sick animals from healthy fresh cows, dedicated footwear and equipment for the maternity and fresh-cow area, and hand hygiene protocols for personnel (WOAH Terrestrial Animal Health Code). The Food and Agriculture Organization of the United Nations (FAO) emphasizes the importance of colostrum quality and timely administration as a cornerstone of neonatal and early postpartum health (FAO Animal Production and Health). In addition, the USDA Animal and Plant Health Inspection Service (APHIS) Livestock and Poultry Disease surveillance programs highlight the need for early detection of infectious diseases such as Johne’s disease, salmonellosis, and [bovine viral diarrhea virus](/knowledge/viruses/livestock-viruses/bovine-viral-diarrhea-virus), which can manifest during the fresh period (USDA APHIS Livestock and Poultry Disease). Implementing a consistent biosecurity plan during the first 21 days reduces both clinical disease and the risk of subclinical infections that impair long-term productivity. #### Diagnostic and Veterinary Escalation When a fresh cow deviates from expected recovery parameters, a structured escalation protocol should guide the decision to involve a veterinarian. The Merck Veterinary Manual notes that conditions such as retained placenta, metritis, clinical ketosis, hypocalcemia, and displaced abomasum occur most frequently in the first three weeks postpartum and require prompt veterinary assessment (Merck Veterinary Manual). Specific triggers for escalation include: - Temperature exceeding 39.7°C (103.5°F) for more than 24 hours despite supportive care. - Decreased feed intake to less than 50% of expected dry matter intake for two consecutive days. - Abnormal uterine discharge (fetid, watery, or copious) accompanied by systemic signs. - Clinical signs of ketosis (decreased milk yield, neurologic signs, and strong odor of acetone on breath) that do not respond to oral propylene glycol within 24 hours. - Recumbency or unsteady gait that is not explained by hypocalcemia or parturient paresis. Uncertainty in diagnosis is inherent, many postpartum disorders present with overlapping signs. For example, a cow with mild metritis may show only a slight drop in feed intake and a normal temperature, while early ketosis can be mistaken for hypocalcemia. In such cases, the veterinarian should be consulted to perform a physical examination, blood chemistry panel (beta-hydroxybutyrate, calcium, nonesterified fatty acids), and possibly ultrasonography to assess the uterus and rumen. The USDA National Animal Health Monitoring System (NAHMS) dairy studies consistently report that farms with written health protocols and regular veterinary herd health visits achieve lower culling rates and higher milk production in fresh cows (USDA National Animal Health Monitoring System). Therefore, the escalation system should not replace veterinary oversight but rather complement scheduled herd health visits. #### Sustainability Sustainable management of fresh cows extends beyond individual animal care to include resource efficiency and long-term herd viability. The FAO Animal Production and Health program advocates for integrated approaches that reduce antibiotic use through improved hygiene, early detection, and targeted treatment (FAO Animal Production and Health). Minimizing the duration and severity of metabolic disorders reduces the environmental footprint of milk production by decreasing the number of cows that fail to reach peak milk or that are culled early. Additionally, maintaining a fresh-cow monitoring system that relies on daily behavioral observation (feeding time, social interactions) instead of invasive procedures aligns with welfare standards and reduces stress. Adequate feeding space (at least 0.6 to 0.9 m of bunk space per cow) is crucial to prevent aggression and ensure that submissive cows have access to feed, as demonstrated by studies on feeding space and inter-cow distance (Effect of feeding space on the inter-cow distance, aggression, and feeding behavior of free-stall housed lactating dairy cows). Such environmental modifications are low-cost sustainability measures that improve health outcomes and reduce the need for therapeutic interventions. ### Frequently Asked Questions **1. How often should I observe fresh cows in the first 21 days?** At minimum, conduct a structured observation twice daily at the same times each day, once before morning feeding and once before evening feeding. More frequent checks (three times daily) are advisable for cows with any deviation from normal. **2. What are the first signs that should trigger a veterinary call?** Any cow that is recumbent, depressed, has a fever over 39.7°C, or has stopped eating for more than 12 hours should be evaluated by a veterinarian immediately. **3. Should I take the temperature of every fresh cow every day?** No. Routine temperature taking of all fresh cows has not been proven to reduce disease incidence. Reserve temperature measurement for cows showing clinical abnormalities such as dullness, decreased feed intake, or abnormal discharge. **4. How do I know if a cow has ketosis without a blood test?** Clinical signs include decreased milk yield, lethargy, loss of appetite, and a strong sweet or acetone odor on the breath. However, subclinical ketosis presents without obvious signs. Blood or milk beta-hydroxybutyrate testing by your veterinarian is the most reliable method. **5. What does inadequate feeding space do to fresh cows?** Insufficient bunk space increases aggression and competition, leading to decreased feed intake in submissive cows. This elevates risk for negative energy balance, ketosis, and displaced abomasum. Provide at least 0.6,0.9 m of linear feeding space per cow. **6. Can I use automated rumination collars for monitoring?** Yes. Changes in rumination time, especially a reduction of more than 20% from baseline, have been associated with health disorders. This technology can complement visual observation but should not replace hands-on evaluation. **7. How long should I keep a sick fresh cow separated from the herd?** Separate sick cows for at least 72 hours after resolution of clinical signs, or longer if there is persistent fever or discharge. Refer to the WOAH Terrestrial Animal Health Code for pathogen-specific guidelines. **8. What role does colostrum management play in fresh cow health?** Colostrum quality and timing directly affect the neonatal calf’s immunity, but also indicate the dam’s metabolic status. Delayed colostrum harvest or poor quality can signal underlying problems such as hypocalcemia or inadequate dry cow nutrition. **Educational Veterinary Notice** This material provides general guidance for monitoring fresh cows but does not replace individualized veterinary advice. Each herd has unique risk factors, and diagnostic decisions should be made in consultation with a licensed veterinarian. Work with your herd veterinarian to establish written protocols for observation, escalation, and treatment that comply with local regulations and industry best practices. ## Related Farming Guides - [Dairy Cattle Farming Nutrition Housing Health Signals And Herd Management](/knowledge/animal-farming/dairy-cattle/dairy-cattle-farming-nutrition-housing-health-signals-and-herd-management) - [Transition Cow Management From Dry Off To Freshening](/knowledge/animal-farming/dairy-cattle/transition-cow-management-from-dry-off-to-freshening) - [Dairy Calf Colostrum Management](/knowledge/animal-farming/dairy-cattle/dairy-calf-colostrum-management) - [Milking Routine And Parlor Hygiene](/knowledge/animal-farming/dairy-cattle/milking-routine-and-parlor-hygiene) - [Dairy Farm Records That Drive Better Decisions](/knowledge/animal-farming/dairy-cattle/dairy-farm-records-that-drive-better-decisions) ## Related Clinical & Scientific Guides * [Evaluating Feed Additives for Dairy Cow Performance](/knowledge/animal-farming/dairy-cattle/evaluating-feed-additives-for-dairy-cow-performance) * [Dairy Barn Fire Safety: Design and Prevention Measures](/knowledge/animal-farming/dairy-cattle/dairy-barn-fire-safety-design-prevention) * [Dairy Cow Pregnancy Loss Records and Review](/knowledge/animal-farming/dairy-cattle/dairy-cow-pregnancy-loss-records-and-review) ## 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.