Equine Brucellosis: Diagnosis and Management

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

Key Takeaways

• Equine brucellosis, primarily caused by Brucella abortus, typically localizes to musculoskeletal structures (tendons, bursae, joints) manifesting as abscessation, fistulous withers, poll suppuration, septic arthritis, or tenosynovitis, unlike the reproductive tropism seen in ruminants.
• The principal risk factor for equine infection is co-habitation or shared environments with infected cattle or pigs, positioning horses as sentinel species that reflect the brucellosis status of sympatric domestic livestock.
• Diagnostic challenges are significant due to the absence of validated species-specific tests; serologic interpretation relies on extrapolating cattle criteria, necessitating integration of clinical signs, exposure history, and confirmatory tests like 2-mercaptoethanol (2-ME) or competitive ELISA (cELISA).
• Molecular detection via PCR on clinical samples (synovial fluid, abscess aspirates) offers high specificity for confirming infection, while bacterial culture, though definitive, is often impractical in live animals and requires specialized BSL-3 containment.
• Management prioritizes biosecurity, wound protection, and human exposure prevention due to the zoonotic potential of Brucella species, requiring strict personal protective equipment and disinfection protocols for veterinary personnel and handlers.
• Treatment involves surgical drainage and lavage combined with antimicrobial therapy, though cure is not guaranteed, and monitoring relies on clinical resolution, serial imaging, and serologic status, with a guarded prognosis for return to athletic function.

Brucellosis in horses is an under-recognized infectious disease caused primarily by Brucella abortus, with occasional involvement of B. suis and B. canis. The condition presents diagnostic challenges because clinical signs are often localized to musculoskeletal structures, serologic testing lacks validated interpretive criteria for equids, and the zoonotic potential places veterinary personnel at risk during examination and sample handling. This article provides practicing veterinarians with a structured approach to recognizing suspect cases, selecting and interpreting diagnostic tests, and managing affected horses while protecting human health. It addresses the epidemiologic context that should raise clinical suspicion, the pathologic basis of characteriztic lesions, and the practical limitations of current laboratory methods.

Equine brucellosis differs fundamentally from the reproductive-focused disease seen in cattle, sheep, and goats. In horses, the infection localizes to tendons, bursae, and joints, producing abscessation and chronic inflammatory changes instead of placentitis or epididymitis. Reproductive disorders are rare in both male and female equids, a distinction that shapes the diagnostic workup and the index of suspicion in practice. The disease in equines reflects the brucellosis status of sympatric domestic species, particularly cattle, and joint management of horses with infected ruminants is the principal risk factor for transmission. Horses, donkeys, and mules can serve as sources of infection for humans, which makes occupational safety a central consideration in case management.

The evidence base for equine brucellosis is limited by the absence of a validated diagnostic test for the species. Serologic assays developed and standardized for cattle are applied to equine samples without species-specific interpretive criteria, and the significance of positive results remains uncertain. This constraint affects prevalence estimates, clinical decision-making, and the interpretation of research findings throughout the literature. The practical consequence is that veterinarians must integrate serologic results with clinical findings, exposure history, and confirmatory testing to reach a defensible diagnosis.

At a Glance

Etiologic Agents and Epidemiology

Brucella abortus is the species most frequently identified in equine infections, consistent with the epidemiologic link between horses and infected cattle herds. The organizm is a facultative intracellular gram-negative coccobacillus that survives within phagocytes and establishes chronic infection in tissues with limited immune clearance. In horses, the organizm shows tropism for synovial structures, tendon sheaths, and bursae, where it incites a pyogranulomatous inflammatory response that progresses to abscess formation and fistulation.

The epidemiologic pattern of equine brucellosis mirrors the disease status of nearby livestock. A review of current understanding emphasizes that disease in equines reflects the brucellosis status of sympatric domestic species, mainly cattle, and that joint breeding of horses with cattle and pigs is the main risk factor for equine infection. Transmission from equines to cattle or among equines is possible but unlikely, which positions the horse as a sentinel species instead of a maintenance host. This distinction matters for control programs: the presence of equine cases should prompt investigation of the shared livestock environment, and elimination of brucellosis in cattle is expected to reduce equine exposure.

Seroprevalence data from endemic regions illustrate the variability of infection pressure. In northern Nigeria, testing of 75 horses in three stables using the Rose Bengal plate test found an overall seroprevalence of 14.7%, with stable-level prevalence ranging from 6.7% to 22.7%. A separate study of 601 donkeys in northeastern Nigeria reported seroprevalence of 7.2% by Rose Bengal plate test and 6.7% by competitive ELISA, with higher rates in males and in the 4 to 6 year age group. In contrast, a cross-sectional study of 420 equines in Tamaulipas, Mexico, found only one reactor by Rose Bengal test and Rivanol test, a result the authors considered false-positive because other horses under identical environmental conditions were negative. These contrasting findings underscore the geographic variability of infection risk and the importance of local epidemiologic context in case assessment.

Pathogenesis and Clinical Pathology

The route of infection in horses is typically oral ingestion of contaminated feed or water, contact of the organizm with skin wounds, or inhalation of infectious aerosols. The organizm penetrates mucosal surfaces, enters regional lymph nodes, and disseminates hematogenously to target tissues. The synovial lining of bursae, tendon sheaths, and joints provides a permissive environment for bacterial persistence, and the resulting inflammatory response is characterized by fibrinopurulent exudate, granulation tissue formation, and progressive tissue destruction.

The classic lesions of fistulous withers and poll suppuration represent chronic infection of the supraspinous bursa and the atlantal bursa, respectively. These conditions develop over weeks to months and are characterized by fluctuant swelling, heat, pain on palpation, and eventual drainage of purulent material through sinus tracts. Septic arthritis and tenosynovitis produce lameness of variable severity, joint effusion, and periarticular swelling. The clinical presentation in racing horses has been described as including bursitis infection, septic tenosynovitis, septic arthritis, and non-specific lameness resulting from joint infections. Abscesses in tendons, bursae, and joints are the hallmark of equine brucellosis, and the distribution of lesions reflects the biomechanical stress and vascular anatomy of these structures.

The absence of reproductive manifestations distinguishes equine brucellosis from the ruminant syndrome. Abortion, placentitis, orchitis, and epididymitis are uncommon in horses, and infertility is not a recognized consequence of infection. This difference likely reflects species-specific host factors, including the distribution of erythritol, a sugar alcohol that promotes Brucella growth in the ruminant placenta and fetal tissues. The equine placenta does not provide the same permissive environment, which redirects the infection to musculoskeletal sites.

Immunologic Response and Diagnostic Implications

The humoral immune response to Brucella infection follows a predictable sequence that serologic tests exploit. IgM antibodies appear first, followed by IgG1 and IgG2 subclasses. The Rose Bengal plate test, a rapid agglutination assay performed at low pH, detects both IgM and IgG and is used as a screening test. The serum agglutination test detects IgM and some IgG but produces false-positive results in the presence of cross-reacting antibodies from other gram-negative organizms. The 2-mercaptoethanol test inactivates IgM, leaving IgG detectable, which improves specificity and correlates more closely with active infection. Competitive ELISA provides an additional confirmatory option with species-independent antigen binding.

The application of these tests to equine samples is complicated by the lack of validated cutoffs. Assays are standardized for bovine serum, and the performance characteriztics in horses, including sensitivity, specificity, and predictive values, are unknown. A study of racing horses in Iran reported that 63 of 876 samples (7.1%) were positive by Rose Bengal plate test, 21 (2.3%) by serum agglutination test, and only 2 (0.2%) by 2-mercaptoethanol test. This progressive reduction in seropositivity across tests of increasing specificity illustrates the risk of overdiagnosis when screening tests are used alone. The same study detected Brucella DNA in 28 of 63 seropositive samples, with 26 identified as B. abortus and 2 as B. suis by Bruce-ladder PCR, demonstrating that molecular confirmation is possible even when serologic results are discordant.

The interpretation of serologic results in horses should therefore follow a probabilistic framework. A positive Rose Bengal plate test in a horse with compatible clinical signs and known exposure to infected cattle supports the diagnosis but does not confirm it. A positive 2-mercaptoethanol test or competitive ELISA increases confidence, and molecular detection of Brucella DNA in tissue, synovial fluid, or abscess contents provides definitive evidence of infection. Negative serologic results do not exclude infection, particularly in early disease or in chronically affected horses with localized abscesses and low circulating antibody titers.

Diagnostic Approach and Testing Strategy

Brucellosis in horses presents a diagnostic challenge because clinical signs overlap with common musculoskeletal conditions and no test has been validated for equine samples. The approach requires integrating exposure history, physical findings, and a testing sequence that acknowledges the limitations of each assay. Equine Brucellosis: Current Understanding and Challenges notes that the absence of a validated diagnostic test for equines limits interpretation of available data.

Clinical Recognition and Case Selection

Suspect brucellosis in horses with supraspinous or suprascapular bursitis, fistulous withers, or septic tendon sheaths that fail to respond to routine antimicrobial therapy. Lameness may be non-specific, and some infected horses show no localizing signs. Equine brucellosis in Iran: serological, bacteriological and molecular analysis describes bursitis infection, septic tenosynovitis, septic arthritis, and non-specific lameness resulting from joint infections as the principal complications.

Reproductive signs are uncommon in horses. Unlike cattle, where abortion and retained placenta dominate the clinical picture, horses rarely exhibit reproductive failure. Equine Brucellosis: Current Understanding and Challenges states that reproductive disorders are rare in both male and female equines. This distinction matters clinically because a mare with pregnancy loss and no musculoskeletal signs is unlikely to have brucellosis, whereas a horse with fistulous withers on a farm with infected cattle warrants investigation.

Exposure History and Risk Assessment

The most important historical feature is cohabitation with cattle, pigs, or other ruminants. Equine Brucellosis: Current Understanding and Challenges identifies joint breeding of horses, cattle, and pigs as the main risk factor for equine brucellosis. Disease in equines generally reflects disease status in sympatric domestic species, mainly cattle. A horse with no cattle contact and no history of shared pasture or water sources has a low pretest probability, and routine screening is not indicated.

Ask specifically about:

• Shared pasture, water sources, or housing with cattle or pigs
• Recent introduction of cattle to the property
• Known brucellosis status of the cattle herd
• Access to aborted bovine fetal material or placentas
• Previous testing of the horse or herdmates

Serologic Testing

Serology remains the primary diagnostic modality, but interpretation requires caution. The Rose Bengal plate test (RBPT) is the most commonly used screening assay in reported studies. Serologic prevalence of brucellosis in horse stables in two northern States of Nigeria used RBPT to identify an overall seroprevalence of 14.7% among 75 horses, while Anti-Brucella abortus antibodies in equids in the state of Goiás, Brazil found 111 of 897 equids reactive on RBPT, with only 40 confirmed by the 2-mercaptoethanol (2-ME) test, giving a confirmed seroprevalence of 4.46%. This discrepancy illustrates a critical point: RBPT overestimates infection in horses, and confirmatory testing is mandatory before assigning a positive status.

The 2-ME test detects IgG and helps distinguish active infection from IgM-dominated non-specific reactivity. Equine brucellosis in Iran: serological, bacteriological and molecular analysis reported that 63 of 876 horses (7.1%) were RBPT-positive, but only 2 (0.2%) were positive on 2-ME testing. The serum agglutination test (SAT) fell between these values at 2.3%. This steep attrition from screening to confirmatory testing means that a single RBPT-positive result in a horse with no clinical signs has limited diagnostic value.

The competitive ELISA (cELISA) offers an alternative confirmatory platform. Serological survey for Brucella antibodies in donkeys of north-eastern Nigeria used RBPT and cELISA in parallel, finding 43 of 601 donkeys (7.2%) positive on RBPT and 40 (6.7%) on cELISA. The closer agreement in that study may reflect the assay characteriztics or the population tested. Where cELISA is available, it provides a useful second-line test that does not rely on species-specific conjugates.

Molecular Testing

PCR can detect Brucella DNA in blood, synovial fluid, abscess contents, or tissue samples. Equine brucellosis in Iran: serological, bacteriological and molecular analysis detected Brucella DNA in 28 of 63 seropositive serum samples (44.5%), with 26 identified as B. abortus and 2 as another species. No seronegative samples yielded Brucella DNA. These findings indicate that PCR on blood has moderate sensitivity in seropositive horses and excellent specificity. A positive PCR confirms infection. A negative PCR does not exclude it, particularly in chronic cases where bacteremia is intermittent or absent.

The Bruce-ladder PCR used in that study distinguishes Brucella species, which matters for epidemiologic tracing and for understanding the source of infection. Sample selection should prioritize lesional tissue when available. Synovial fluid from an affected joint or aspirate from a fistulous tract carries a higher organizm load than peripheral blood in chronic cases.

Bacteriologic Culture

Culture is the definitive diagnostic method but is rarely practical in live horses. Organizms may be shed intermittently, and culture of blood, milk, or vaginal swabs from seropositive horses frequently yields no growth. Equine brucellosis in Iran: serological, bacteriological and molecular analysis attempted culture on milk, blood, and vaginal swabs from seropositive horses, but the study relied on PCR for species identification. Culture of abscess contents or synovial fluid collected aseptically at surgery offers the best yield. Laboratory personnel must be notified of the suspected diagnosis because Brucella requires specialised media, prolonged incubation, and Biosafety Level 3 containment.

Diagnostic Algorithm

The following sequence applies to a horse with clinical signs compatible with brucellosis or a known exposure:

1. Record exposure history, including cattle and pig contact.
2. Perform a complete physical examination with particular attention to the withers, supraspinous bursa, tendon sheaths, and joints.
3. Collect serum for RBPT as the screening test.
4. If RBPT is negative and clinical suspicion is low, stop testing. If clinical suspicion remains high despite a negative RBPT, proceed to PCR on blood or lesional fluid.
5. If RBPT is positive, run a confirmatory assay. The 2-ME test is the most accessible option in many regions. cELISA is preferred where available.
6. If confirmatory testing is positive, collect lesional samples for PCR and culture where feasible.
7. Interpret all results in the context of clinical signs. A seropositive horse with no clinical signs and no known exposure may represent non-specific reactivity, particularly if only RBPT was positive.

Management Checklist

Management of equine brucellosis centers on three objectives: treating the individual horse, protecting human handlers, and preventing spread to other animals.

Individual Horse Management

• Confirm the diagnosis before committing to long-term therapy.
• Treat fistulous withers and septic bursitis with surgical drainage and lavage combined with antimicrobial therapy. Current formulary and label references must be consulted for drug selection, dose, and duration.
• Provide analgesia and joint support for septic arthritis and tenosynovitis.
• Monitor response through serial lameness examinations, ultrasound assessment of affected bursae or tendon sheaths, and repeat synovial fluid analysis where applicable.
• Prognosis for return to athletic function is guarded, particularly when articular structures are involved.

Zoonotic Risk Management

• Treat all confirmed or suspected cases as infectious to humans. Equine Brucellosis: Current Understanding and Challenges states that equines represent significant Brucella spp. infection sources for humans.
• Wear impermeable gloves, eye protection, and a surgical mask when handling blood, synovial fluid, abscess contents, or placental material.
• Restrict access to the horse to designated personnel.
• Clean and disinfect contaminated equipment and surfaces. Brucella is susceptible to standard hospital disinfectants, but organic material must be removed before disinfection.
• Advise owners and handlers to seek medical evaluation if they develop fever, malaise, or joint pain after exposure.
• Report confirmed cases to the relevant animal health authority. Reporting requirements vary by jurisdiction, and the WOAH terrestrial animal health standards provide international guidance on notification and surveillance.

Herd and Population Considerations

• Test in-contact horses on the same property.
• Investigate the source of infection. Because equine disease reflects disease status in sympatric domestic species, a confirmed equine case should prompt evaluation of the cattle herd. Equine Brucellosis: Current Understanding and Challenges notes that evaluation of the disease in equines can serve as an indirect indicator of the effectiveness of brucellosis control measures in other domestic species.
• Separate horses from cattle and pigs where possible, particularly during calving and farrowing seasons.
• Prevent access to aborted fetuses, placentas, and contaminated water sources. Prevalence of Brucella abortus antibodies in equines of a tropical region of Mexico identified shared pond water with cattle and dogs as a potential risk factor, although that study ultimately classified the single positive result as false-positive.
• Do not breed from confirmed positive horses. The risk of venereal transmission is poorly characterized, but the zoonotic risk to breeding personnel and the potential for vertical transmission justify this precaution.

Monitoring Parameters

Serologic monitoring has limitations. Antibody titres may persist for months after clinical resolution, and a declining titre does not guarantee bacteriologic cure. Conversely, a rising 2-ME titre during or after therapy suggests ongoing infection and warrants reassessment of the treatment plan.

Regional

Recognized Complications and Early Detection

The principal complications of equine brucellosis are localized suppurative lesions instead of systemic dissemination. Fistulous withers, poll evil, septic arthritis, septic tenosynovitis, and bursitis dominate the clinical picture, with non-specific lameness frequently the only presenting complaint Dorneles et al., current understanding and challenges. These lesions develop insidiously, often over weeks to months, and may be mistaken for traumatic injuries or foreign body reactions.

Early detection depends on recognizing that a non-healing, draining tract over the withers or poll, or a persistently swollen joint or tendon sheath unresponsive to routine therapy, warrants specific investigation. Serial ultrasonography is the most useful monitoring tool. Track the dimensions and echogenicity of abscess cavities, the integrity of surrounding bursal and tendinous structures, and the response to drainage and lavage. Radiography is indicated when osseous involvement is suspected, particularly in cases of septic arthritis where periarticular new bone or subchondral lysis may develop. Repeat serologic testing during and after treatment is of limited value for monitoring resolution, because antibody titres may persist for months after clinical recovery and no validated test exists for equine brucellosis Dorneles et al., current understanding and challenges.

A recognized failure mode is the development of secondary bacterial infection within a Brucella abscess after empirical drainage. This complicates subsequent culture and confounds the clinical picture. Submit aspirates for aerobic and anaerobic culture before initiating antimicrobial therapy, and always request Brucella-specific culture conditions when the history supports exposure risk.

Common Diagnostic Errors and Corrective Action

The most frequent error is dismissing a positive screening test as a false positive without confirmatory testing. The Rose Bengal plate test is a screening tool with imperfect specificity, and positive results require confirmation with a more specific assay such as the 2-mercaptoethanol test or competitive ELISA Amini et al., serological, bacteriological and molecular analysis. In one Iranian study, 7.1% of horses were RBPT-positive but only 0.2% were positive by 2-ME, illustrating the substantial overcall rate of screening alone Amini et al., serological, bacteriological and molecular analysis.

A second common error is overinterpreting a single positive result in an endemic area without considering the animal's signalment and exposure history. Seroprevalence varies widely by region and management system, from 0.238% in parts of Mexico to 14.7% in Nigerian stables Acosta-González et al., prevalence in equines of tropical Mexico, Ehizibolo et al., serologic prevalence in Nigerian horse stables. A positive test in a horse with no cattle contact, no clinical signs, and no travel history should be interpreted cautiously.

A third error is failure to collect appropriate samples before starting antimicrobials. Antibiotic therapy rapidly reduces the yield of blood culture and may render molecular testing unreliable. Collect serum, whole blood, synovial fluid, and abscess aspirates before treatment begins.

Limitations of Current Evidence

The evidence base for equine brucellosis is thin. No diagnostic test has been validated for horses, and most serologic assays were developed for cattle Dorneles et al., current understanding and challenges. Reported seroprevalence figures vary enormously across studies, reflecting differences in test protocols, study populations, and regional disease pressure instead of true biologic variation. The Mexican study concluded that equines are not a reservoir and play no important role in regional epidemiologic patterns, while Nigerian and Iranian studies suggest ongoing exposure and potential transmission risk Acosta-González et al., prevalence in equines of tropical Mexico, Amini et al., serological, bacteriological and molecular analysis. These divergent conclusions reflect genuine uncertainty about the epidemiologic role of equids.

Expert opinion differs on the value of treating infected horses. Some authorities recommend culling seropositive animals in endemic herds, while others support treatment of valuable individuals with prolonged antimicrobial protocols. Neither approach is supported by controlled trials. The zoonotic risk is the one point of consensus: equines represent a significant infection source for humans, and all diagnostic and therapeutic decisions must account for this Dorneles et al., current understanding and challenges.

Referral, Consultation, and Reporting

Referral is warranted when fistulous withers or poll evil involves deep structures, when septic arthritis or tenosynovitis threatens joint or tendon function, or when the diagnosis remains uncertain after initial testing. Specialist referral to a surgeon or internal medicine service is appropriate for advanced imaging, surgical debridement, or prolonged antimicrobial therapy under hospital conditions.

Laboratory consultation is essential before submitting samples for Brucella culture. The organizm is a significant laboratory hazard, and diagnostic laboratories require advance notice to handle samples under appropriate containment. Molecular testing for Brucella DNA is increasingly available and may be performed on serum, whole blood, or tissue, but results must be interpreted in the context of serology and clinical findings Amini et al., serological, bacteriological and molecular analysis.

Regulatory reporting obligations vary by jurisdiction. In many countries, brucellosis is a notifiable disease, and confirmed or suspected cases must be reported to the relevant animal health authority. The World Organization for Animal Health maintains international standards for surveillance and trade-related disease control, and veterinarians should consult these standards and their national regulations when a case is identified WOAH terrestrial animal health standards. Reporting serves both public health and livestock disease control objectives, because equine infection is an indirect indicator of disease status in sympatric cattle populations Dorneles et al., current understanding and challenges.

Frequently Asked Questions

How Should I Proceed When Confirmatory Testing Is Unavailable in My Practice Setting?

When reference laboratories are inaccessible or cost prohibitive, interpret screening results with explicit caveats. A positive Rose Bengal test in a horse with compatible lesions supports a working diagnosis, but the test has no validated performance characteriztics in equines, so false positives occur Equine Brucellosis: Current Understanding and Challenges. Pair screening with a second method such as the 2-mercaptoethanol test or competitive ELISA when either is available, and document that confirmatory testing was declined or unavailable. Treat the horse as potentially infected for biosecurity and zoonotic purposes while awaiting further testing or clinical resolution. Contact your regional veterinary diagnostic laboratory to ask which Brucella assays they accept for equine samples and whether they can provide interpretive guidance for this species.

What Biosecurity Measures Should I Recommend for a Horse With Suspected Brucellosis?

Isolate the horse from cattle, pigs, and other equids, since transmission between equids and cattle is possible though uncommon Equine Brucellosis: Current Understanding and Challenges. Drain and manage abscesses with strict wound precautions, as suppurative lesions contain viable organizms. Wear gloves, protective outerwear, and eye protection when handling discharges or performing procedures. Disinfect contaminated surfaces with standard hospital-grade disinfectants active against Brucella species. Restrict access to the horse to essential personnel, and clearly label the isolation area. Advise pregnant household members and immunocompromised individuals to avoid contact entirely. Continue these measures until definitive test results or clinical cure is achieved, and coordinate with public health authorities if human exposure has occurred.

How Do I Interpret a Seropositive Horse That Has No Clinical Signs?

Subclinical seropositivity occurs and may reflect exposure without active infection, cross-reaction, or persistent antibody from resolved disease. Reported seroprevalence in apparently healthy horses ranges widely, from 0.2% in Mexico to 14.7% in Nigeria, depending on regional livestock disease pressure Serologic prevalence of brucellosis in horse stables in two northern States of Nigeria. In endemic areas, a positive screening test in a healthy horse warrants confirmatory testing and repeat sampling in 30 to 60 days. Rising titres on paired samples suggest active infection, stable or falling titres favour past exposure or nonspecific reactivity. Do not treat the horse with antimicrobials based on serology alone. Recheck the animal periodically and advise owners that the zoonotic significance of a stable positive titre without clinical disease remains uncertain.

What Should I Tell an Owner Who Is Worried About Family Members Becoming Ill?

Explain that Brucella abortus is zoonotic and that horses can serve as a source of human infection, particularly through contact with infected discharges or contaminated equipment Equine Brucellosis: Current Understanding and Challenges. Reassure the owner that routine handling of a horse without open lesions carries low risk, but strict hygiene is mandatory. Advise against allowing children, pregnant women, or immunocompromised persons to groom, feed, or clean stalls for the affected horse. Instruct the owner to wash hands thoroughly after any contact, to wear gloves when changing bandages or cleaning stalls, and to seek medical evaluation if fever, malaise, or joint pain develops within weeks to months of exposure. Provide a written summary the owner can share with their physician.

How Should I Document This Case in the Medical Record?

Record the exposure history, including contact with cattle, pigs, or contaminated water sources, since co-mingling with ruminants is the principal risk factor for equine infection Equine Brucellosis: Current Understanding and Challenges. Document the clinical findings, lesion location, and the specific tests performed with laboratory accession numbers. Note which confirmatory tests were recommended but declined, and record the owner's informed consent for that decision. Include the zoonotic risk discussion and the biosecurity instructions provided. Flag the record for follow-up at 30 and 60 days. If the horse is euthanized or dies, note that postmortem sampling for culture and PCR is strongly recommended to confirm the diagnosis and to inform public health follow-up.

Does Brucellosis in Horses Respond to Antimicrobial Therapy?

Published data on treatment outcomes in horses are extremely limited, and no validated treatment protocol exists for equine brucellosis Equine Brucellosis: Current Understanding and Challenges. Combination antimicrobial regimens used in other species may be attempted, but cure is not assured and relapse is possible. Surgical drainage of abscesses, bursal hygromas, and septic joints is often the more important intervention, combined with aggressive wound management. Consult a current veterinary formulary for drug selection and dosing, and discuss the uncertain prognosis with the owner before committing to prolonged therapy. Monitor response through serial clinical examination, ultrasound of affected structures, and repeat serology. If the horse does not improve, reconsider the diagnosis and pursue culture or PCR to confirm Brucella infection before continuing treatment.

Related Clinical & Scientific Guides

• Diagnostic Approach to Canine Infertility in the Bitch
• Canine Neonatal Resuscitation: Protocol and Monitoring
• Equine Breeding Soundness Examination of the Stallion

References and Further Reading

• Equine Brucellosis: Current Understanding and Challenges.. 2023.
• Serologic prevalence of brucellosis in horse stables in two northern States of Nigeria.. 2011.
• Prevalence of Brucella abortus antibodies in equines of a tropical region of Mexico.. 2006.
• Equine brucellosis in Iran: serological, bacteriological and molecular analysis.. 2024.
• Anti-Brucella abortus antibodies in equids in the state of Goiás, Brazil.. 2025.
• Serological survey for Brucella antibodies in donkeys of north-eastern Nigeria.. 2017.
• Society for Theriogenology Resources. Society for Theriogenology.
• MSD Veterinary Manual, Professional Edition. MSD Veterinary Manual.
• American Veterinary Medical Association Practice Resources. American Veterinary Medical Association.

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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.