# Poultry Necropsy: Systematic Approach for Flock Diagnosis


## Key Takeaways

- The primary objective of a poultry necropsy is flock-level diagnosis, focusing on identifying the most common, treatable, or contagious condition to limit further population loss, rather than solely determining the cause of death in an individual bird.
- A systematic approach is critical, beginning with careful bird selection (3-5 live, early-stage affected birds and 3-5 recently dead birds) and a thorough external examination assessing body condition, dehydration, vent soiling, and integumentary changes before internal organ assessment.
- Biosafety is paramount, requiring dedicated tools, disinfectants, and respiratory protection due to the zoonotic potential of agents like Salmonella, Campylobacter, and avian influenza, alongside adherence to reportable disease obligations.
- Internal examination follows a standardized organ order (skin, musculoskeletal, coelomic cavity, GI tract, liver/spleen, respiratory, cardiovascular, urogenital, nervous system) with meticulous documentation of lesion distribution and severity, often necessitating photography with a scale marker.
- Tissue sampling strategies are dictated by suspected etiology: fresh tissues for culture and PCR (e.g., liver, spleen, bone marrow for septicemia; tracheal swabs for respiratory disease), and fixed tissues (10% neutral buffered formalin) for histopathology (e.g., brain, lung, intestine for various systemic diseases).
- Integrating flock context, including mortality curves, production records, feed/water intake, and vaccination status, with necropsy findings is essential for formulating defensible, population-level recommendations and interventions.

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Poultry necropsy serves a fundamentally different purpose than companion animal post mortem examination. The patient is the flock, not the individual bird, and every incision, observation, and sample collection must answer questions about population-level disease, management failure, or environmental insult. This article provides a systematic necropsy protocol for the practicing veterinarian who examines chickens, turkeys, and other production poultry. It covers case selection, biosafety, external examination, internal organ assessment, lesion interpretation, and sampling strategy for confirmatory diagnostics.

The clinical question that drives a poultry necropsy is rarely "what killed this bird?" It is "what is happening in this flock, and what intervention will limit further loss?" The individual bird is a biological sample that represents a production cohort. A single necropsy can mislead if the veterinarian does not understand how the bird was selected, how many birds should be examined, and how lesions distribute across a population. This article equips the reader to convert post mortem findings into defensible flock-level recommendations.

## At a Glance

| Parameter | Decision or Fact |
|---|---|
| Bird selection | Submit 3 to 5 live, untreated birds showing early clinical signs plus 3 to 5 recently dead birds |
| Primary objective | Identify the most common, most treatable, or most contagious condition first |
| Biosafety level | Assume zoonotic potential, use dedicated tools, disinfectant, and respiratory protection |
| External exam priority | Assess body condition, dehydration, vent soiling, skin, comb, wattles, eyes, and nares before incision |
| Systematic organ order | Skin and subcutaneous tissues, musculoskeletal, coelomic cavity, gastrointestinal tract, liver and spleen, respiratory, cardiovascular, urogenital, nervous system |
| Key lesion documentation | Photograph, describe distribution (focal, multifocal, diffuse), and record severity on a standardized form |
| Sample selection | Fresh tissues for culture and PCR, fixed tissues for histopathology, paired serum for serology |
| Flock context | Always integrate mortality curve, production records, feed intake, and water consumption with necropsy findings |

## Purpose and Limitations of the Flock Necropsy

The diagnostic yield of poultry necropsy depends on case selection. A bird that died after prolonged illness may show secondary infections, emaciation, and autolysis that obscure the primary lesion. A bird euthanized in early disease may show minimal gross change but provide the best samples for pathogen detection. The veterinarian should request both categories: live, affected birds that can be humanely euthanized and examined immediately, and recently dead birds that represent the mortality pattern. Birds that have been dead for more than a few hours in warm conditions are of limited value for histopathology and bacteriology due to autolysis and post mortem bacterial overgrowth.

Flock history must be gathered before the first incision. Mortality curve shape, age of onset, vaccination status, source flock, feed changes, and recent introductions all direct the examination. A sudden spike in mortality with no prodromal illness suggests a toxic, metabolic, or highly virulent infectious cause. A slowly rising curve with stunting and unevenness suggests a management or nutritional problem. The [MSD Veterinary Manual](https://www.msdvetmanual.com/) provides species-specific guidance on common poultry diseases and their expected lesion patterns, which serves as the baseline reference for interpreting findings.

## Biosafety and Necropsy Facility Considerations

Poultry necropsy carries zoonotic and occupational risks that the veterinarian must manage deliberately. Salmonella, Campylobacter, avian influenza, and Newcastle disease virus are among the agents that can be transmitted from carcasses to humans. Respiratory protection, cut-resistant gloves, and eye protection are minimum standards. The necropsy area should be nonporous, easily disinfected, and dedicated to avian work if possible. Tools should be cleaned and disinfected between birds to prevent cross-contamination of samples.

The veterinarian must also consider reportable disease obligations. Certain poultry pathogens trigger statutory reporting requirements that vary by jurisdiction. The [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) define internationally notifiable diseases and provide guidance on surveillance and control. The [USDA APHIS livestock and poultry disease resources](https://www.aphis.usda.gov/livestock-poultry-disease) describe national reporting frameworks in the United States. The veterinarian should confirm local requirements before necropsy when a highly contagious or zoonotic agent is suspected, and should contact the appropriate authority immediately if lesions suggest a notifiable disease.

## Necropsy Technique: External Examination

Begin with the intact bird. Record body weight and compare it to the breed or strain standard for the age. Assess body condition by palpating the pectoral muscles and noting the prominence of the keel bone. A sharp keel with concave pectoral muscles indicates chronic weight loss. Dehydration is estimated by skin turgor, dryness of the oral mucosa, and sunken eyes. Examine the vent for fecal soiling, which suggests diarrhea or cloacal disease. Inspect the comb and wattles for cyanosis, swelling, or vesicular lesions. Check the eyes for discharge, corneal opacity, or swelling of the periorbital sinuses. Examine the nares and oral cavity for exudate, caseous plugs, or mucosal lesions.

Skin lesions deserve particular attention. Ectoparasites, trauma from cannibalism, and cellulitis all produce characteriztic changes. Feather loss patterns may indicate molting, ectoparasite infestation, or behavioral problems. Examine the shanks and footpads for bumblefoot, swelling, or deformities. Palpate the crop for impaction, emptiness, or abnormal distension. The external examination often reveals the first clues that direct the internal examination, and it should never be skipped even when the history strongly suggests a specific diagnosis.

## Euthanasia and Immediate Post Mortem Changes

Live birds submitted for necropsy must be euthanized humanely before examination. Cervical dislocation is acceptable for small birds when performed correctly, but the method must be confirmed as acceptable under local welfare standards. The [AVMA professional practice resources](https://www.avma.org/resources-tools) provide guidance on acceptable euthanasia methods for poultry. After euthanasia, examine the bird immediately. Post mortem changes such as rigor mortis, hypostasis, and autolysis progress rapidly in birds due to their high body temperature and small body mass. The liver and intestine autolyze within hours, which can mimic or obscure true lesions. If necropsy cannot be performed within a few hours, refrigerate the carcass but do not freeze it, as freezing destroys cellular detail needed for histopathology.

## Systematic Internal Examination

Begin the internal examination with the bird in dorsal recumbency. Reflect the skin over the pectoral region and assess the pectoral muscles for mass, color, and moisture. Severe pectoral atrophy with gelatinous serous atrophy indicates chronic starvation or prolonged disease. Petechial or ecchymotic hemorrhages in the pectoral musculature may reflect septicemia, trauma, or a bleeding diathesis.

Incise the abdominal wall lateral to the sternum on both sides, then reflect the sternum cranially to expose the coelomic cavity. Alternatively, cut through the ribs and coracoid bones to remove the entire sternal plate. The latter approach improves access to the thoracic viscera and is preferred when cardiac or pulmonary lesions are suspected. Note the presence and character of coelomic fluid. Clear, straw-colored fluid in small volume is common in acute death. Turbid fluid, fibrin clots, or caseous exudate indicate peritonitis, often secondary to egg peritonitis in layers or ruptured viscera.

Assess the air sacs systematically. The thoracic and abdominal air sacs should be thin, transparent, and glistening. Cloudiness, thickening, or caseous exudate indicates airsacculitis. The distribution of air sac lesions helps prioritize differentials. Diffuse caseous airsacculitis with perihepatitis and pericarditis in a young bird strongly suggests colibacillosis or mycoplasmosis. Focal caseous nodules within air sac walls raise suspicion for aspergillosis, particularly in older birds or those with a history of poor ventilation.

## Organ-Specific Examination

Examine the heart in situ before removal. Note pericardial fluid volume and clarity. Pericardial effusion, fibrinous pericarditis, or caseous pericardial exudate accompany colibacillosis, mycoplasmosis, and Pasteurella multocida infection. Endocarditis in poultry is less common than in mammals but occurs with enterococcal and staphylococcal infections. When valvular vegetations are present, the causative organizm is frequently a gram-positive coccus, although fastidious and intracellular bacteria can produce culture-negative endocarditis in other species and should be considered when routine culture fails [Brouqui and Raoult, institutional publication on endocarditis due to rare and fastidious bacteria](https://pubmed.ncbi.nlm.nih.gov/11148009/). Open the ventricles and atria and inspect the valves and myocardium.

Examine the liver for size, color, and surface character. An enlarged, friable, mottled liver with pinpoint white foci suggests colibacillosis, salmonellosis, or fowl cholera. Multiple pale nodules of variable size raise suspicion for Marek's disease, lymphoid leukosis, or tuberculosis. A green-tinged liver indicates bile stasis and chronic anorexia. Examine the spleen similarly, splenomegaly with mottling accompanies septicemic conditions and viral infections including infectious bursal disease and Marek's disease.

Evaluate the gastrointestinal tract segment by segment. Open the esophagus and crop and note the contents, mucosal appearance, and the presence of caseous plaques. Crop wall thickening with white caseous plaques suggests candidiasis. Examine the proventriculus and gizzard together. Proventricular enlargement with thickening of the wall and loss of the normal glandular pattern is characteriztic of proventriculitis, which may be viral or nutritional in origin. Inspect the gizzard lining for erosion, ulceration, or discolouration. Gizzard erosion with dark, tarry contents in young birds suggests adenovirus infection or a dietary factor.

Open the small intestine along its length and examine the mucosa. Diffuse hemorrhagic enteritis with luminal blood suggests coccidiosis in the upper tract or clostridial enteritis. Focal raised white plaques in the duodenum are typical of coccidiosis. Examine the caeca separately. Caecal cores, firm caseous plugs within the caecal lumen, are characteriztic of histomoniasis, though they also occur with caecal coccidiosis and salmonellosis. Examine the pancreas for pallor, fibrosis, or nodularity. Pancreatic atrophy with fibrosis accompanies avian influenza and other viral infections.

## Reproductive and Urinary Systems

In laying hens, examine the ovary and oviduct. A regressed, inactive ovary with small follicles indicates a break in lay, which may be physiological or disease related. A ruptured, hemorrhagic follicle with free yolk in the coelom confirms egg peritonitis. Caseous material within the oviduct lumen suggests salpingitis, often bacterial. In males, examine the testes for asymmetry, atrophy, or neoplasia.

Examine the kidneys for swelling, pallor, or urate deposition. Urate distension of the ureters and visceral gout, white chalky urate deposits on the pericardium, liver, and air sacs, indicate renal failure, dehydration, or a nephrotoxic insult. Visceral gout in young birds should prompt consideration of infectious bronchitis virus nephropathogenic strains or water deprivation.

## Nervous System and Skeletal Examination

Examine the brain when neurological signs were reported in the flock. Reflect the calvarium and note meningeal congestion, hemorrhage, or edema. Encephalomalacia with cerebellar hemorrhage suggests vitamin E deficiency in young birds. Meningeal opacity or exudate accompanies bacterial meningitis. Examine the sciatic nerves bilaterally. Unilateral or bilateral enlargement with loss of striation is characteriztic of Marek's disease. Examine the brachial and celiac plexuses similarly.

Assess the skeletal system for fractures, deformities, and growth plate abnormalities. Tibial dyschondroplasia presents as a retained cartilage plug at the proximal tibiotarsal growth plate. Rickets shows widened, irregular growth plates with soft bone. Examine the joints for swelling, excess fluid, or caseous exudate. Bacterial arthritis, often staphylococcal or mycoplasmal, produces turbid joint fluid and synovial thickening.

## Lesion Documentation and Photography

Document every lesion with a consistent nomenclature. Record the organ, the lesion type, the distribution, and the severity. Use a standardized form or template that includes bird identification, flock history, and a body system checklist. Photograph significant lesions before collection. Include a scale marker and the bird identification in each image. Store images with the case record for future comparison and for discussion with the producer or diagnostic laboratory.

## Tissue Sampling and Submission

Select tissues for histopathology from freshly euthanised birds. Fix tissues in 10% neutral buffered formalin at a ratio of at least 10 parts fixative to 1 part tissue. Submit brain, heart, liver, spleen, kidney, lung, trachea, proventriculus, gizzard, intestine, pancreas, bursa of Fabricius, thymus, and any grossly abnormal tissue. For birds under 16 weeks of age, include the bursa and thymus to assess immune organ status.

Collect samples for bacteriology using sterile technique before formalin fixation. Swab the liver, spleen, and bone marrow, or collect tissue cores in sterile containers. Refrigerate, do not freeze, samples intended for bacterial culture. For virus isolation or PCR, collect fresh tissue in sterile containers on ice and ship overnight. The choice of samples depends on the suspected aetiology and the available diagnostic tests. Consult the receiving laboratory before submission when the clinical picture is unclear, as test panels vary by laboratory and region.

The table below summarizes sample selection by suspected disease category.

| Suspected condition | Samples for histopathology | Samples for microbiology | Samples for molecular testing |
|---|---|---|---|
| Septicemia | Liver, spleen, lung, heart | Liver, spleen, bone marrow, aerobic culture | Blood or tissue for PCR |
| Respiratory disease | Trachea, lung, air sac, conjunctiva | Tracheal swab, air sac, aerobic and Mycoplasma culture | Tracheal or oropharyngeal swab for PCR |
| Enteric disease | Intestine at multiple levels, caeca, pancreas | Intestinal content, aerobic and anaerobic culture | Intestinal content or feces for PCR |
| Neurological disease | Brain, sciatic nerve, spinal cord | Brain, meningeal swab, aerobic culture | Brain for PCR |
| Immunosuppression | Bursa, thymus, spleen, bone marrow | Not routinely indicated | Bursa or spleen for PCR |

When a notifiable disease is suspected, contact the relevant animal health authority before shipping samples. National and international reporting frameworks govern the response to highly pathogenic avian influenza, Newcastle disease, and other listed pathogens, and the necropsy findings must be reported promptly [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). The same reporting obligation applies in many jurisdictions through national veterinary services [USDA APHIS livestock and poultry disease information](https://www.aphis.usda.gov/livestock-poultry-disease). Confirm the local reporting pathway before beginning the necropsy when the flock history includes sudden high mortality, neurological signs, or respiratory disease of rapid onset.

## Recognized Complications and Early Detection

The most consequential failure in poultry necropsy is incomplete flock-level interpretation. A single bird's lesions may misrepresent the group when the clinician selects a chronically affected bird instead of an acutely affected one. Chronically affected birds often show secondary infections, emaciation, and tissue depletion that obscure the primary pathogen. Early detection of this failure mode requires asking the producer which birds are most representative of the current mortality pattern and selecting at least two acutely affected birds alongside one chronic case.

Decomposition artefacts constitute the second major complication. Post mortem autolysis begins within minutes in poultry due to high body temperature and thin skin. Greenish discolouration of the abdominal wall, gas accumulation in the viscera, and hemoglobin imbibition of vessel walls can mimic bacterial peritonitis or clostridial disease. The discriminating check is timing: if more than four hours have elapsed since death at ambient temperature, autolysis confounds interpretation. Refrigerate carcasses promptly and necropsy within 12 hours. Freezing destroys cellular detail and renders histopathology uninterpretable, though it preserves tissues for PCR and culture.

Iatrogenic artefacts from the necropsy itself are the third category. Cutting into the intestine before examining the liver and spleen contaminates surfaces with enteric flora. Clamping or crushing tissue with forceps creates artefacts that mimic necrosis. The corrective action is a disciplined sequence: open the coelomic cavity, photograph in situ, examine serosal surfaces, then remove organs before incising any portion of the gastrointestinal tract.

| Observation | Likely cause | Discriminating check |
|---|---|---|
| Green abdominal wall, gas, foul odour | Autolysis or clostridial overgrowth | Time since death, anaerobic culture of liver |
| Diffuse serosal opacity and fibrin | Bacterial peritonitis | Gram stain of fibrin, culture of air sac and liver |
| Pale swollen liver with focal necrosis | Bacterial septicemia, possibly colibacillosis or fowl cholera | Liver culture, impression smear with Gram stain |
| Hemorrhagic intestinal mucosa | Coccidiosis, clostridial enteritis, or autolysis | Mucosal scraping for oocysts, histopathology of preserved gut |
| Enlarged pale kidneys with urate distension | Dehydration, nephropathogenic virus, or post mortem change | Urate deposition pattern, fresh kidney for virus isolation |

## Common Errors and Corrective Actions

Less experienced clinicians frequently misidentify the bursa of Fabricius as a lesion. The bursa involutes with age and shrinks to a small dorsal remnant, which may be mistaken for atrophy caused by immunosuppressive viruses such as infectious bursal disease. The corrective action is to record bursal size relative to age and to confirm atrophy histologically instead of grossly alone.

Another recurring error is the failure to examine the trachea and lungs in birds that die suddenly. The syrinx and primary bronchi are easily overlooked when the clinician focuses on the coelomic viscera. Open the trachea along its entire length and examine the lungs by slicing transversely. Exudate, caseous plugs, or hemorrhage in these sites distinguishes respiratory pathogens from septicemic processes.

A third error is the collection of inappropriate samples. Swabs taken from the body cavity after organ manipulation recover contaminants. Tissues placed in formalin for PCR degrade nucleic acids. The corrective action is to collect aseptically before dissection, use separate sterile instruments for culture and for gross examination, and divide each tissue sample into formalin and refrigerated sterile containers before the necropsy proceeds.

## Limitations of Current Evidence and Divergent Expert Opinion

The evidence base for poultry necropsy interpretation rests heavily on field experience and case series instead of controlled trials. Expert opinion differs on the value of routine histopathology versus culture as the primary diagnostic modality. Some diagnosticians argue that aerobic culture alone identifies most bacterial causes, while others maintain that histopathology is essential to distinguish primary pathogens from secondary invaders, particularly in immunosuppressed flocks. The [MSD Veterinary Manual](https://www.msdvetmanual.com/) presents both approaches as complementary, and the prudent clinician uses culture, histopathology, and molecular testing in parallel when the diagnosis is not immediately obvious.

Interpretation of lesion significance also varies. Mild tracheal congestion, for example, may be an agonal change, an artefact of euthanasia method, or an early viral infection. No published threshold reliably separates these possibilities, and the clinician must weigh flock history, clinical signs, and the distribution of lesions across multiple birds. Where the evidence base is thin, the practitioner should state the uncertainty in the necropsy report and recommend confirmatory testing instead of asserting a definitive diagnosis.

## Referral, Consultation, and Regulatory Reporting

Referral to a veterinary diagnostic laboratory is warranted when gross lesions are equivocal, when the flock is valuable, when the condition is suspected to be zoonotic, or when the clinician lacks the equipment for specialised testing. Laboratories provide histopathology, bacteriology, virology, serology, and toxicology under one submission. The [USDA APHIS animal health information](https://www.aphis.usda.gov/livestock-poultry-disease) portal lists reportable diseases and submission guidance for the United States, while the [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) define international reporting obligations for listed diseases.

Regulatory reporting is mandatory for notifiable diseases including highly pathogenic avian influenza, Newcastle disease, and virulent forms of infectious laryngotracheitis in some jurisdictions. The clinician should contact the relevant authority before the necropsy if a notifiable disease is suspected, because sample handling and disposal may be regulated. The [AVMA practice resources](https://www.avma.org/resources-tools) provide guidance on professional obligations and public health responsibilities. When a zoonotic agent such as Salmonella or Erysipelothrix is identified, the clinician should inform the producer and recommend appropriate precautions for workers handling birds and eggs. The [FAO animal production and health guidance](https://www.fao.org/animal-production/en/) offers international context for disease surveillance and reporting in production systems.

## Frequently Asked Questions

### How many birds should I necropsy when investigating a flock problem?

Select six to ten birds that represent the range of clinical presentations, including acutely affected, chronically affected, and apparently healthy birds. When mortality is ongoing, include birds that died within the past two hours and moribund birds euthanized on site. If the problem is localized, sample birds from multiple houses or pens to distinguish a management issue from an infectious process. Submit additional live birds for laboratory examination when antemortem sampling is needed. The diagnostic yield of a flock necropsy depends more on case selection than on total number, and a poorly chosen single bird can misdirect the entire investigation.

### What can I do when a full necropsy set is not available?

A scalpel blade, sharp scissors, and clean forceps can complete most of the examination. Use a clean, disinfected surface such as a plastic cutting board or a disposable tray. Substitute a heavy knife for bone shears when opening the skull and a sturdy pair of scissors for rib cutters. Collect tissues in any leak-proof container with formalin, and use sterile swabs in transport medium for bacteriology. Document the limitations of your equipment in the record so that negative findings are interpreted with appropriate caution. Referral to a diagnostic laboratory remains appropriate when field findings are inconclusive or when regulatory disease is suspected.

### How should I prioritize sampling when the owner has a limited budget?

Start with the highest-yield samples: fresh liver, spleen, and intestine in transport medium for bacteriology and virology, plus formalin-fixed heart, liver, kidney, lung, and brain for histopathology. If only one sample type is affordable, choose formalin-fixed tissues, because histopathology provides a permanent record and can guide targeted testing later. Reserve polymerase chain reaction testing for specific differential diagnoses supported by gross lesions. Discuss the cost of each test with the owner before submission and explain that a limited panel may require a second submission if initial results are inconclusive.

### How does the necropsy approach differ for waterfowl or game birds?

Waterfowl and game birds share the same general technique, but several anatomical and practical differences matter. Waterfowl have larger bursae of Fabricius and more prominent lymphoid tissue in the gut-associated tracts, and their feathers are denser and more waterproof, so wetting the plumage before plucking speeds exposure. Game birds such as pheasants and quail are smaller, requiring finer instruments and more careful handling of the heart and liver. Species-specific susceptibility to certain pathogens, such as duck virus enteritis in waterfowl or avian influenza in gallinaceous birds, should guide the differential list and the samples collected.

### What records should I keep from a flock necropsy?

Record the date, farm identification, species, breed, age, and the number of birds examined. Document the clinical history, mortality pattern, and gross findings for each bird using a standardized form or body diagram. Photograph significant lesions with a scale marker and store images with the case file. Note the samples collected, the tests requested, and the laboratory submission number. Keep a copy of the final laboratory report with the necropsy record. These records support longitudinal flock health monitoring and may be needed for regulatory investigations or certification programs.

### How do I explain necropsy findings to a producer who expects a definitive diagnosis?

Present the findings as a list of confirmed lesions and probable causes, and distinguish between what is proven and what remains uncertain. Explain that some diseases produce identical gross lesions and require laboratory confirmation. Use the flock history to connect the lesions to management factors such as stocking density, ventilation, or feed changes. Provide a written summary with the submitted samples and the expected timeline for results. If the findings suggest a reportable disease, explain the regulatory process and the steps you will take, referring to [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) and [USDA APHIS livestock and poultry disease programs](https://www.aphis.usda.gov/livestock-poultry-disease) for the relevant reporting requirements.

## Related Clinical & Scientific Guides

* [Rumen Health Assessment in Dairy Cows: Clinical and Subclinical Indicators](/knowledge/veterinary-medicine/food-animal-medicine/rumen-health-assessment-dairy-cows-clinical-subclinical-indicators)
* [Mastitis Control Programs in Dairy Herds: Monitoring and Prevention](/knowledge/veterinary-medicine/food-animal-medicine/mastitis-control-programs-dairy-herds-monitoring-prevention)
* [Swine Nutrition and Health: Feed-Related Disease Diagnosis](/knowledge/veterinary-medicine/food-animal-medicine/swine-nutrition-health-feed-related-disease-diagnosis)


## References and Further Reading

- [Endocarditis due to rare and fastidious bacteria.](https://pubmed.ncbi.nlm.nih.gov/11148009/). 2001.
- [USDA APHIS Animal Health Information](https://www.aphis.usda.gov/livestock-poultry-disease). USDA APHIS.
- [FAO Animal Production and Health](https://www.fao.org/animal-production/en/). FAO.
- [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual.
- [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association.
- [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). WOAH.

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> This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.