Diagnostic Approach to Respiratory Disease in Sheep and Goats

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-11

Key Takeaways

• Thoracic ultrasonography is the preferred imaging modality in small ruminants for detecting cranioventral consolidation and pleural effusion, offering superior diagnostic yield compared to radiography due to ease of use in standing animals.
• Deep transtracheal washes or bronchoalveolar lavages are the samples of choice for bacterial culture and cytology, providing direct access to lower respiratory tract pathogens, whereas nasal swabs have limited diagnostic value for pneumonia.
• Key bacterial differentials include Mannheimia hemolytica, Pasteurella multocida, Bibersteinia trehalosi, and Mycoplasma ovipneumoniae, with viral infections often acting as primary insults that predispose to secondary bacterial invasion.
• Notifiable diseases such as Contagious Caprine Pleuropneumonia (CCPP) and Ovine Pulmonary Adenocarcinoma (OPA) require prompt identification and regulatory reporting, with OPA potentially diagnosed antemortem via CT imaging or PCR for jaagsiekte sheep retrovirus.
• Zoonotic pathogens like Coxiella burnetii and Chlamydia spp. necessitate careful handling protocols, and their presence should be considered in the differential diagnosis, particularly in goats.
• Flock-level assessment of attack rate, age distribution, and temporal spread is crucial for distinguishing contagious diseases from management-related issues and for guiding the diagnostic investigation.

Respiratory disease in sheep and goats is a leading cause of morbidity, mortality, and production loss in small ruminant flocks worldwide. The diagnostic challenge is substantial: the clinical signs of tachypnea, nasal discharge, cough, and fever are shared across viral, bacterial, parasitic, and non-infectious causes, and the differential list varies with age, management system, and geographic region. This article provides a structured diagnostic framework for the practicing veterinarian, moving from signalment and history through physical examination, thoracic imaging, and laboratory testing to a prioritized differential diagnosis. The emphasis is on clinical reasoning that distinguishes the common endemic pathogens from the notifiable and zoonotic diseases that require regulatory intervention.

The approach is organized around the question the clinician must answer at each stage: is this an upper or lower respiratory tract problem, is it infectious or non-infectious, and does the pattern of disease in the group suggest a single agent or a multifactorial complex? The framework applies to individual animals presented to a clinic and to flock-level investigations on farm. Treatment and control strategies are not covered here, the focus is exclusively on reaching a defensible diagnosis.

At a Glance

Pathophysiology of Respiratory Disease in Small Ruminants

The ovine and caprine respiratory tract shares the general mammalian defense architecture: mucociliary clearance, alveolar macrophages, and regional lymphoid tissue. Several features of small ruminant anatomy and physiology modify disease expression. The relatively narrow trachea and mainstem bronchi predispose to rapid airway occlusion by exudate. The apical and cardiac lung lobes are the most dependent in the standing animal and are the most frequent sites of cranioventral bronchopneumonia. The diaphragmatic lobes are more commonly affected in embolic or hematogenous spread.

The lung responds to injury through a limited repertoire. Acute bacterial infection produces a fibrinopurulent bronchopneumonia with a cranioventral distribution. Chronic infection leads to abscessation, often with a thick capsule that resists antimicrobial penetration. Viral infections such as parainfluenza-3 virus and respiratory syncytial virus damage the ciliated epithelium and deplete the mucociliary escalator, creating a permissive environment for secondary bacterial invasion. The clinical consequence is that most severe pneumonia in sheep and goats is bacterial, even when the initiating event was viral.

Parasitic pneumonia follows a different pattern. Muellerius capillaris and Protostrongylus rufescens are the lungworms of sheep and goats, the former produces multifocal granulomatous nodules in the subpleural parenchyma of the diaphragmatic lobes, while the latter inhabits the larger airways. Neither produces the cranioventral consolidation typical of bacterial pneumonia. Dictyocaulus filaria, the large lungworm, occupies the trachea and bronchi and causes a verminous bronchitis that can mimic bacterial disease clinically.

The Flock-Level Diagnostic Frame

Respiratory disease in small ruminants is rarely a single-animal problem. The clinician should establish the attack rate, the age distribution of affected animals, and the temporal pattern of spread. A high attack rate over a short period in lambs and kids points toward a viral or mycoplasmal epizootic with secondary bacterial pneumonia. A low attack rate with sporadic cases in adults raises the possibility of ovine pulmonary adenocarcinoma (OPA), caseous lymphadenitis with pulmonary involvement, or a chronic suppurative process.

The production system modifies the differential list. Intensively housed lambs on high-concentrate rations are at risk for the classic enzootic pneumonia complex, in which M. ovipneumoniae and Mannheimia hemolytica interact with environmental stressors. Pastured animals are more likely to present with lungworm or with pasteurellosis triggered by handling, transport, or weather events. Goats differ from sheep in their susceptibility to contagious caprine pleuropneumonia (CCPP), caused by Mycoplasma capricolum subsp. capripneumoniae, a disease that is notifiable in many countries and that produces a fibrinous pleuropneumonia with a high case fatality rate. The WOAH terrestrial animal health standards list CCPP among the diseases subject to international reporting obligations.

Zoonotic risk should be assessed before handling animals with respiratory signs. Coxiella burnetii, the agent of Q fever, can be shed in birth products and less commonly in respiratory secretions of goats and sheep. The MSD Veterinary Manual provides species-specific guidance on zoonotic respiratory pathogens of small ruminants. Cryptococcosis, although uncommon, has been documented in sheep and can present with lower respiratory signs, a retrospective study from Western Australia identified a single ovine case among 155 domestic animal cryptococcosis cases over an 11-year period, with Cryptococcus gattii predominating in the non-feline species examined cryptococcosis in domestic animals in Western Australia.

Physical Examination and Localization

The physical examination must determine the anatomic site of disease. Nasal discharge, sneezing, and stertor localize to the upper airways. Cough, tachypnea, and abnormal lung sounds localize to the lower tract. The clinician should auscult the trachea and all lung fields in a quiet environment, comparing the right and left hemithorax. Cranioventral crackles and bronchial tones support bronchopneumonia. Absent or reduced sounds over the ventral thorax with a horizontal dorsal gas line suggest pleural effusion or severe consolidation. A pleuritic friction rub indicates fibrinous pleuritis, which is characteriztic of CCPP and of severe M. hemolytica infection.

Thoracic percussion is underused in small ruminants but is valuable for detecting the large intrathoracic masses of OPA or abscessation. Percussion dullness over the ventral thorax with a fluid line supports effusion. Hyperresonance is uncommon in sheep and goats because pneumothorax is rare.

Fever is not a reliable discriminator. Many sheep with advanced OPA are normothermic. Animals with chronic abscessation may have intermittent fever. The absence of fever does not exclude bacterial pneumonia.

Imaging and Ultrasonography

Thoracic ultrasonography is the imaging modality of choice in small ruminants. The normal lung surface produces a continuous hyperechoic line with reverberation artifact. Consolidation appears as hypoechoic parenchyma with arborizing hyperechoic bronchi, the so-called hepatization pattern. Abscesses appear as well-circumscribed hypoechoic cavities with hyperechoic rims. Pleural effusion is readily identified as anechoic fluid dorsal to the lung. Ultrasonography can be performed in the standing animal with minimal restraint and is superior to radiography for detecting the cranioventral consolidation typical of bacterial pneumonia.

Radiography requires general anesthesia or heavy sedation in most sheep and goats, which carries risk in animals with compromised respiratory function. When performed, the lateral view is most useful. The classic radiographic pattern of OPA is a diffuse interstitial to alveolar pattern with a caudodorsal distribution, often with a soft tissue mass in the caudal thorax. The MSD Veterinary Manual describes the imaging features of the major small ruminant respiratory diseases.

Computed tomography is the most sensitive antemortem test for OPA, detecting nodules and masses that are invisible on radiographs. It requires general anesthesia and is reserved for valuable breeding animals or for cases where the diagnosis is uncertain after less invasive testing.

Sample Collection and Laboratory Submission

The diagnostic plan for respiratory disease in sheep and goats depends on whether the goal is individual animal diagnosis, outbreak investigation, or exclusion of reportable pathogens. Sample quality determines laboratory yield more than any other factor. Collect samples before initiating antimicrobial therapy whenever possible, because prior treatment rapidly reduces bacterial culture sensitivity and complicates Mycoplasma isolation.

Nasal and Nasopharyngeal Swabs

Nasal swabs are easy to collect but have limited diagnostic value for lower respiratory tract pathogens. The nasal cavity of healthy small ruminants harbours commensal bacteria, including Pasteurella multocida and Mannheimia hemolytica, so a positive culture from a nasal swab does not confirm the cause of pneumonia. Nasopharyngeal swabs improve detection of viral pathogens, particularly when collected during the acute phase of disease within the first three to five days of clinical signs. Use a guarded swab or a long sterile swab inserted to the level of the medial canthus of the eye, and place the swab in viral or bacterial transport medium according to the intended assay.

For Mycoplasma species, use a swab with charcoal or Amies transport medium and refrigerate the sample immediately. Mycoplasmas are fastidious and do not survive ambient temperature transport well. The Animal and Plant Health Agency identification service in England and Wales uses a combination of culture and 16S rRNA gene-based PCR-denaturing gradient gel electrophoresis for mollicute identification, and submission protocols for such reference laboratories should be followed precisely Mycoplasma species identification from ruminants in England and Wales.

Tracheal Aspirates and Bronchoalveolar Lavage

Tracheal aspiration and bronchoalveolar lavage (BAL) provide samples from the lower airways and are the preferred antemortem samples for bacterial and cytological diagnosis. Perform BAL in a standing, lightly sedated animal using a sterile urinary catheter passed through an endotracheal tube. Infuse 20 to 60 mL of sterile saline in divided aliquots and aspirate gently. The first aliquot often represents bronchial instead of alveolar content and may be submitted separately for cytology.

BAL fluid should be divided into sterile tubes for bacteriology, EDTA tubes for cytology, and plain tubes for molecular testing. Cytological evaluation of BAL fluid distinguishes suppurative inflammation, which supports bacterial bronchopneumonia, from eosinophilic inflammation, which suggests parasitic pneumonia such as that caused by Dictyocaulus filaria or Muellerius capillaris. A predominance of neutrophils with intracellular bacteria supports a bacterial aetiology, whereas mononuclear cell predominance is more consistent with viral or Mycoplasma infection.

Lung Aspiration and Postmortem Sampling

Percutaneous lung aspiration is indicated when a discrete consolidated lesion is identified by ultrasonography and a specific bacterial diagnosis is required. Ultrasound guidance reduces the risk of pneumothorax. Use a 20 gauge, 4 to 5 cm needle attached to a 10 mL syringe, and aspirate while withdrawing. Submit the aspirate for culture and, if volume permits, PCR for Mycoplasma ovipneumoniae and respiratory viruses.

Postmortem examination is the single most valuable diagnostic step in a flock outbreak. Select animals that have not been treated recently and that represent the typical clinical presentation. Collect lung tissue from the interface between consolidated and normal parenchyma, plus tracheal mucosa, mediastinal lymph nodes, and nasal turbinates. Submit samples in formalin for histopathology, in sterile containers for culture, and frozen for PCR. Histopathology is particularly important for detecting viral pathogens and for identifying lesions consistent with ovine pulmonary adenocarcinoma, which cannot be confirmed by culture alone.

Laboratory Testing and Interpretation

Bacterial Culture and Antimicrobial Susceptibility

Culture lung tissue, BAL fluid, or tracheal aspirates on blood agar and MacConkey agar, with an additional selective medium for Mycoplasma species. Mannheimia hemolytica and Pasteurella multocida grow readily on blood agar within 24 to 48 hours. Bibersteinia trehalosi also grows on blood agar and is an important cause of systemic pasteurellosis in sheep, particularly after stress or transport. Mycoplasma species require specialised media and prolonged incubation, and many veterinary diagnostic laboratories do not offer routine Mycoplasma culture. PCR is more sensitive than culture for Mycoplasma ovipneumoniae and is the preferred diagnostic method Mycoplasma species identification from ruminants in England and Wales.

Antimicrobial susceptibility testing is warranted when treatment failure occurs or when a herd-level control program is being designed. Interpret susceptibility results with caution because in vitro susceptibility does not always predict clinical response in respiratory disease, particularly for intracellular pathogens such as Mycoplasma species.

Viral Diagnostics

PCR panels for respiratory viruses are available from many commercial laboratories and can detect parainfluenza virus type 3, respiratory syncytial virus, adenovirus, and ovine herpesvirus 2. Sample selection depends on the suspected pathogen. For malignant catarrhal fever, whole blood in EDTA is the preferred antemortem sample, and PCR detects ovine gammaherpesvirus 2 DNA. Histopathology with immunohistochemistry or in situ hybridisation confirms intralesional viral participation malignant catarrhal fever review.

Influenza D virus has been detected in sheep, but seroprevalence in diagnostic samples from sheep is low compared with cattle, and routine testing of individual sheep for influenza D is rarely indicated influenza D seroprevalence in Irish livestock. Bovine viral diarrhea virus can infect sheep and goats, and should be considered when respiratory disease is accompanied by reproductive failure or ill-thrift BVDV infections in pigs and other species.

Serology

Serology has limited value for diagnosing acute respiratory disease because paired samples are required to demonstrate a rising titre, and treatment decisions cannot wait for convalescent samples. Serology is more useful for herd-level surveillance and for documenting exposure to specific pathogens. A single high titre in an individual animal confirms exposure but does not confirm current disease.

Differential Prioritization by Signalment and Lesion Pattern

Documentation and Reporting

Record the signalment, vaccination history, movement history, and treatment history for every case. Document the distribution of affected animals within the flock, the progression of clinical signs over time, and the response to any treatment already administered. This information is essential for interpreting laboratory results and for designing control measures.

Photograph thoracic ultrasound images and gross postmortem lesions. Store images with the case record so that response to treatment can be assessed objectively. Record the ultrasonographic appearance of the lung surface, the presence and character of pleural fluid, and the distribution of consolidated areas.

For suspected reportable diseases, contact the relevant veterinary authority before collecting and shipping samples. The World Organization for Animal Health terrestrial animal health standards provide the framework for notification and for the diagnostic requirements of listed diseases WOAH terrestrial animal health standards. National programs for disease surveillance and reporting are described by the United States Department of Agriculture Animal and Plant Health Inspection Service USDA APHIS livestock and poultry disease information. Contagious caprine pleuropneumonia is a WOAH-listed disease, and any suspicion must be reported immediately.

Decision Points That Change the Diagnostic Plan

The diagnostic approach changes when the animal is valuable, when the flock is large, when a reportable disease is suspected, or when the production system involves housed versus pastured animals. A single valuable breeding ram with acute pneumonia warrants immediate BAL and thoracic ultrasound, whereas a flock outbreak in a commercial meat flock may justify moving directly to postmortem examination of representative animals.

Housed animals are at higher risk for viral and bacterial pneumonia transmission, while pastured animals are more likely to have parasitic pneumonia. Goats are more susceptible to Mycoplasma species than sheep, and contagious caprine pleuropneumonia must be considered in any goat with pleuritic pain, fever, and respiratory distress, particularly in regions where the disease is endemic or where goats have been imported.

The availability of point-of-care ultrasound changes the diagnostic sequence. Ultrasonography can confirm consolidation, identify pleural effusion, and guide sampling within minutes, allowing the clinician to prioritize animals for further testing and to make immediate decisions about treatment and isolation.

Recognized Complications and Early Detection

Respiratory disease in sheep and goats follows several failure trajectories that the clinician should anticipate. The most consequential is progression from focal bronchopneumonia to fibrinous pleuropneumonia with pleural effusion, which markedly worsens prognosis and complicates antimicrobial delivery. Ultrasonography performed at initial examination and repeated at 48 to 72 hours detects this transition before auscultatory changes become obvious. Loss of the normal hyperechoic pleural line, anechoic pleural fluid, or atelectatic lung margins indicate extension that warrants thoracocentesis for cytology and culture.

Chronic suppurative pneumonia with abscessation represents a second failure mode, particularly with Trueperella pyogenes or Mycoplasma ovipneumoniae involvement. These cases respond incompletely to therapy and become persistent shedders within the flock. Thoracic radiography or advanced ultrasonography identifies cavitary lesions, but the more practical early indicator is failure to improve within 72 hours of appropriate therapy combined with persistent nasal discharge and weight loss.

Sepsis and bacteremic spread constitute a third complication. Mannheimia hemolytica can produce fulminant septicemia, especially in lambs and kids under stress. Early detection relies on serial temperature monitoring, assessment of mucous membrane perfusion, and recognition of concurrent joint swelling or meningeal signs. Blood culture collected before antimicrobial administration confirms bacteremia and guides agent selection.

Common Diagnostic Errors and Corrective Actions

Less experienced clinicians frequently misattribute chronic coughing to parasitism without performing respiratory localization. Lungworm (Dictyocaulus filaria, Muellerius capillaris) produces coughing that is often indistinguishable from early bacterial pneumonia on history alone. Fecal examination using the Baermann technique, not simple flotation, is the discriminating test. A negative Baermann result does not exclude lungworm in early infection, so response to anthelmintic trial may be needed.

A second recurring error is over-reliance on a single nasal swab for bacterial culture. The upper respiratory tract of healthy small ruminants carries commensal and potentially pathogenic organizms, so a positive culture from a nasal swab does not confirm the cause of lower airway disease. Tracheal aspirate or bronchoalveolar lavage culture is required for meaningful interpretation. When only nasal swabs are available, results should be reported as supportive instead of diagnostic.

Failure to consider viral co-infection is another common gap. Parainfluenza-3 virus, respiratory syncytial virus, and bovine viral diarrhea virus can infect sheep and goats and predispose to secondary bacterial pneumonia. BVDV infections in pigs and other ruminants illustrate how pestiviruses cross species boundaries and complicate diagnostic interpretation. Acute and convalescent serology or PCR on nasal swabs collected early in the course distinguishes primary viral from primary bacterial disease.

Limitations of Current Evidence

The evidence base for respiratory diagnostics in small ruminants is thinner than for cattle. Much of what is applied clinically is extrapolated from bovine medicine, and species-specific validation is often absent. Mycoplasma species identification in ruminants has improved with molecular methods, but the clinical significance of detecting multiple species in a single animal remains uncertain. Identification of Mycoplasma species from ruminants in England and Wales shows that M. bovis dominates cattle submissions, but the small ruminant mycoplasma picture is more varied and less clearly linked to specific syndromes.

Influenza D virus seroprevalence in sheep is low in at least one European population, but the respiratory significance of this virus in small ruminants is not established. Seroprevalence of influenza D virus in Irish cattle, sheep and pigs found limited exposure in sheep, which suggests it is not a major primary pathogen in this species, yet routine diagnostic panels rarely include it.

Expert opinion differs on the value of empirical therapy before sampling. Some clinicians treat first and sample only non-responders, arguing that sampling delays therapy and adds cost. Others advocate sampling before any antimicrobial administration, particularly in outbreaks, because a single accurate culture can direct therapy for the entire group. The correct approach depends on the value of the animals, the chronicity of the problem, and whether this is an index case or a recurring flock issue.

Referral, Consultation, and Regulatory Reporting

Referral to a veterinary diagnostic laboratory is warranted when a case fails to respond to rational therapy, when multiple animals are affected despite intervention, or when the clinical presentation suggests a notifiable or emerging pathogen. Contagious caprine pleuropneumonia, caused by Mycoplasma capricolum subsp. capripneumoniae, is a WOAH-listed disease in many regions, and suspicion should trigger immediate laboratory contact. WOAH terrestrial animal health standards define reporting obligations that vary by jurisdiction, and the attending veterinarian should confirm local requirements before acting.

Malignant catarrhal fever should be considered when respiratory signs accompany mucosal ulceration, corneal opacity, and neurological signs in animals with sheep contact. A review of malignant catarrhal fever in Brazil emphasizes that histopathology, immunohistochemistry, and in situ hybridisation are needed to confirm intralesional ovine gammaherpesvirus-2 participation, and that vascular lesions must be assessed comprehensively instead of relying on lymphocytic vasculitis alone.

Specialist consultation with a veterinary internal medicine or food animal diplomate is appropriate for persistent flock problems, for valuable individual animals, and when the diagnostic plan requires advanced imaging or bronchoscopy beyond routine practice. State or national veterinary diagnostic laboratories provide necropsy services that are often the highest-yield diagnostic step in a flock outbreak, and early submission of a freshly euthanised affected animal frequently resolves cases that serial antemortem sampling cannot.

Frequently Asked Questions

How Do I Prioritize Diagnostics When the Flock Owner Has a Limited Budget?

Start with the least expensive, highest-yield steps: a thorough history, full physical examination of affected and in-contact animals, and thoracic auscultation. These cost nothing and often narrow the differential list substantially. If only one laboratory test is possible, request a deep nasal swab or tracheal aspirate for bacterial culture, since treatable bacterial pneumonia is common. Pool samples from several affected animals only when the question is flock-level, not individual. Postmortem examination of a single representative case frequently outperforms multiple live-animal tests for the same cost. Discuss the trade-off between diagnostic certainty and treatment cost openly, and document that the owner accepted a reduced diagnostic plan.

What Should I Do When Ultrasonography Is Not Available?

Thoracic percussion and auscultation remain useful when imaging is unavailable. Percuss the cranial and ventral lung fields, comparing left and right sides, and listen for increased bronchovesicular sounds, crackles, or wheezes. A painful response to chest pressure or a grunt on expiration suggests pleuritic disease. If you suspect consolidation, a blind tracheal aspirate or bronchoalveolar lavage can still be performed without ultrasound guidance, though the risk of sampling error increases. In goats, remember that normal lung sounds are often louder than in sheep, so do not overinterpret. When imaging is unavailable and the animal is deteriorating, postmortem examination is the most reliable route to a diagnosis.

How Does the Diagnostic Approach Differ Between Sheep and Goats?

The framework is similar, but the differential priorities shift. Goats are more frequently affected by Mycoplasma capricolum subsp. capripneumoniae, the cause of contagious caprine pleuropneumonia, which is a WOAH-listed disease with serious trade implications. Sheep are more often affected by ovine pulmonary adenocarcinoma and by sheep-associated malignant catarrhal fever, where sheep are the asymptomatic reservoir host. Goats also appear more susceptible to lungworm infections in some regions. When you suspect a notifiable disease, consult the WOAH terrestrial animal health standards and your national veterinary authority before proceeding with further sampling.

What Records Should I Keep During a Respiratory Disease Investigation?

Record the date, the number of animals at risk, the number affected, and the number dead. For each examined animal, note body condition score, rectal temperature, respiratory rate and effort, nasal discharge character, and auscultation findings. Keep a copy of every laboratory submission form and result. Photograph gross lesions at postmortem and store images with the case file. Record treatments given, including product, dose, route, and withdrawal periods, since treatment history affects culture interpretation. Maintain a flock-level timeline showing when clinical signs began and how they spread. These records support regulatory reporting if a notifiable disease is confirmed and help you recognize recurrence patterns in subsequent years.

How Do I Explain a Tentative Diagnosis to the Owner Without Overcommitting?

Use language that separates what is confirmed from what is suspected. State that the physical findings are consistent with pneumonia but that the specific cause is not yet known. Explain that bacterial, viral, and parasitic causes can look identical in early disease and that laboratory testing is needed to distinguish them. Give the owner a short list of the most likely causes for their specific flock and signalment. Clarify that some causes, such as mycoplasmal pneumonia, respond poorly to standard antibiotics, while others, such as lungworm, respond well to anthelmintics. Set expectations for the timeline of laboratory results and state clearly what you will do differently once results return.

When Should I Suspect a Notifiable or Emerging Disease?

Suspect a notifiable disease when you see rapid spread, high morbidity, high mortality, or lesions that do not match common endemic pathogens. Contagious caprine pleuropneumonia should be considered in goats with severe pleuropneumonia, especially where goats have been moved or imported. Malignant catarrhal fever should be considered when sheep and cattle are co-housed and cattle develop severe systemic disease. Mycoplasma identification services in some countries have documented shifts in the species recovered from ruminant respiratory samples, so unusual culture results deserve attention. Contact your national veterinary authority early instead of late, since delayed reporting can complicate disease control and trade. The USDA APHIS livestock and poultry disease information and FAO animal production and health guidance provide regional contact points and reporting expectations.

Related Clinical & Scientific Guides

• Rumen Health Assessment in Dairy Cows: Clinical and Subclinical Indicators
• Mastitis Control Programs in Dairy Herds: Monitoring and Prevention
• Swine Nutrition and Health: Feed-Related Disease Diagnosis

References and Further Reading

• Associations between pneumonia and residential distance to livestock farms over a five-year period in a large population-based study.. 2018.
• A review of the epidemiological, clinical, and pathological aspects of malignant catarrhal fever in Brazil.. 2020.
• Bovine viral diarrhea virus (BVDV) infections in pigs.. 2013.
• Seroprevalence of influenza D virus in selected sample groups of Irish cattle, sheep and pigs.. 2019.
• Identification of Mycoplasma species and related organizms from ruminants in England and Wales during 2005-2019.. 2021.
• Cryptococcosis in domestic animals in Western Australia: a retrospective study from 1995-2006.. 2009.
• USDA APHIS Animal Health Information. USDA APHIS.
• FAO Animal Production and Health. FAO.
• MSD Veterinary Manual, Professional Edition. MSD Veterinary Manual.

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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.