# Antimicrobial Stewardship in Equine Practice: Challenges and Solutions


## Key Takeaways

- Antimicrobial stewardship in equine practice is crucial for preserving drug efficacy and optimizing clinical outcomes, balancing individual patient needs against the population-level threat of antimicrobial resistance.
- Inappropriate dose rates and dosing intervals, particularly for penicillin, are common prescribing problems, necessitating verification of pharmacokinetic and pharmacodynamic evidence for all prescribed doses.
- Critically important antimicrobials, such as third-generation cephalosporins, require heightened justification for use, with a preference for narrow-spectrum agents when pathogen identification is possible.
- A significant surveillance gap exists in the USA, with no national or state-level programs tracking antibiotic use in horses, highlighting the need for practice-level data collection and policy development.
- The emergence of ESBL-producing Enterobacteriaceae in companion animals, including horses, warrants urgent action due to the potential for transmission of resistant bacteria and resistance genes between horses, other animals, and humans (One Health imperative).
- Core stewardship actions include prioritizing culture and sensitivity testing, optimizing antimicrobial doses and durations, and robust client education to ensure judicious use and mitigate resistance development.

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Antimicrobial stewardship in equine practice is the coordinated effort to preserve the effectiveness of antimicrobial drugs while optimizing clinical outcomes for horses. This article provides a clinical reference for practising veterinarians who treat horses, covering the scientific basis of stewardship, the specific challenges posed by equine patients and practice structures, and practical strategies for improving prescribing behavior. It addresses how to balance the obligation to treat individual patients against the population-level threat of antimicrobial resistance, and it examines the evidence base for current prescribing patterns.

The equine industry carries substantial economic weight worldwide, and infectious bacterial diseases in horses can produce severe health problems, economic losses, and restrictions on movement and trade. Antibiotics remain the primary treatment for bacterial infections in horses, yet resistance to clinically important drugs now poses significant challenges to equine health and welfare. The adverse effects of antimicrobial overuse and the escalating threat of resistance underscore why stewardship matters in this species. Limited epidemiological information exists on antimicrobial-resistant bacterial infections in horses, which complicates evidence-based decision making. This article synthesises the available literature and professional guidance to give equine practitioners a workable framework for judicious antimicrobial use.

## At a Glance

| Parameter | Key Information |
|---|---|
| Primary goal of stewardship | Preserve antimicrobial efficacy while achieving optimal clinical outcomes for the individual horse |
| Most common prescribing problem | Inappropriate dose rates and dosing intervals, particularly for penicillin in horses |
| High-priority drugs | Third-generation cephalosporins and other critically important antimicrobials require heightened justification |
| Key surveillance gap | No national or state-level programs track antibiotic use in horses in the USA |
| Practice-level tool | Written antimicrobial use or stewardship policies are present in only about half of surveyed practices |
| Resistance concern | ESBL-producing Enterobacteriaceae in companion animals, including horses, warrant urgent action |
| One Health relevance | Resistant bacteria and resistance genes can transfer between horses, other animals, and humans |
| Core stewardship actions | Culture and sensitivity testing, dose optimization, duration minimization, and client education |

## Defining Antimicrobial Stewardship in Equine Context

Antimicrobial stewardship involves the judicious use of antimicrobials, balanced against the requirement to treat the presenting clinical condition. The same mandate and principles discussed in human medicine and other veterinary disciplines apply to equine practice. Stewardship is not simply restriction or reduction of antimicrobial use. It is a systematic approach to selecting the right drug, at the right dose, by the right route, for the right duration, and only when a bacterial infection is confirmed or strongly suspected.

The [principles of judicious antimicrobial use published by the AVMA](https://www.avma.org/resources-tools/one-health/antimicrobial-use-and-antimicrobial-resistance) provide the professional foundation for stewardship decisions in equine practice. These principles emphasize that antimicrobials should be used only when clinically indicated, that narrow-spectrum drugs should be preferred when the pathogen is known or likely, and that therapeutic failure should prompt reassessment instead of automatic escalation. The [World Organization for Animal Health terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) additionally frame antimicrobial use within international animal health and trade obligations, recognizing that resistance is a transboundary concern.

## The Resistance Threat in Equine Patients

The emergence of extended-spectrum beta-lactamases (ESBLs) in gram-negative bacteria isolated from companion animals represents a particularly serious development. Beta-lactams are among the most important antimicrobial groups in veterinary medicine, and ESBL-producing Enterobacteriaceae can render these drugs ineffective, leaving limited therapeutic options and increasing the risk of treatment failure. The close contact between owners and their horses, combined with the movement of horses between premises and events, creates pathways for the transmission of resistant bacteria and resistance genes between horses, other animals, and humans. This [One Health dimension of ESBL resistance in companion animals](https://pubmed.ncbi.nlm.nih.gov/21462862/) makes stewardship in equine practice a matter of public health relevance, also an individual practice concern.

The [comprehensive review of antimicrobial resistance in equines](https://pubmed.ncbi.nlm.nih.gov/39200013/) highlights that the epidemiology of resistant infections in horses remains poorly characterized. This knowledge gap affects clinical decision making because practitioners cannot always predict which pathogens are likely to be resistant in a given region or population. The review also emphasizes the public health significance of transmission dynamics between horses and other animals, reinforcing that responsible antimicrobial use in equine practice protects both horse health and broader community health.

## Current Prescribing Patterns and Their Failures

Survey data from equine practices reveal prescribing behaviors that fall short of stewardship ideals. A study of antibiotic prescribing in small animal and equine practices in Minnesota and North Dakota found that 25.8% of all consults across species involved an antibiotic prescription, with third-generation cephalosporins the most commonly prescribed systemic antibiotic class. The same study noted that topical antibiotic preparations were prescribed frequently, often concurrently with systemic antibiotics. These patterns suggest opportunities for more selective use, particularly of broad-spectrum and critically important drugs. The [quarterly survey of antibiotic prescribing in small animal and equine practices](https://pubmed.ncbi.nlm.nih.gov/35643964/) underscores that antibiotic use measurement is a key component of stewardship, yet no national or state-level programs currently track antibiotic use in horses in the USA.

A separate survey of equine veterinarians in the UK and Europe found that only 54.4% of respondents worked in practices with a written antimicrobial use or stewardship policy, and over half did not perform any environmental surveillance for resistance. The [antimicrobial prescribing and resistance surveillance survey in equine practice](https://pubmed.ncbi.nlm.nih.gov/35575046/) also used clinical case scenarios to explore prescribing decisions, revealing variability in how practitioners approach common infections. These findings indicate that stewardship infrastructure, including written policies and surveillance programs, is inconsistently implemented across equine practices.

Dose selection represents a specific and remediable failure mode. A survey of Australian veterinarians found that doses of procaine penicillin in horses were often low, with 68% of respondents reporting doses unlikely to achieve plasma concentrations above minimum inhibitory concentrations for common equine pathogens. Frequency of penicillin administration was also frequently inappropriate. The [analysis of antimicrobial labeling in Australia](https://pubmed.ncbi.nlm.nih.gov/29691852/) identified that antimicrobial labels themselves sometimes recommend incorrect dose rates, potentially contributing to poor prescribing practices. This finding matters because practitioners who follow label directions in good faith may still underdose their equine patients, promoting both clinical failure and selection for resistance. Current formulary and label references must be consulted for specific dose recommendations, and practitioners should verify that the doses they prescribe are supported by pharmacokinetic and pharmacodynamic evidence.

## Why Equine Practice Presents Distinct Stewardship Challenges

Several features of equine practice complicate stewardship efforts. Horses are large animals with substantial body mass, making drug costs a genuine consideration in treatment decisions. The value of the individual horse, whether as a competition animal, breeding stock, or companion, can create pressure to use broad-spectrum or newer antimicrobials empirically instead of waiting for culture results. The [review of antimicrobial stewardship in equine practice](https://pubmed.ncbi.nlm.nih.gov/31236925/) identifies the need for improved client education, faster and more accurate techniques for pathogen identification and sensitivity testing, and the development of novel antimicrobial agents as key priorities.

Equine practice also spans a wide range of clinical contexts, from ambulatory field practice to referral hospital settings. Field practitioners may lack immediate access to diagnostic laboratory services, making culture and sensitivity testing logistically difficult. Hospital-based practitioners face different pressures, including the need to manage nosocomial infection risks and the expectation of referral clinicians to provide definitive treatment. The diversity of equine practice settings means that stewardship strategies must be adaptable to the resources and constraints of each practice environment.

## The One Health Imperative

Antimicrobial resistance does not respect species boundaries. The [review of antimicrobial resistance in equines](https://pubmed.ncbi.nlm.nih.gov/39200013/) emphasizes transmission dynamics between horses and other animals within a One Health framework. Horses can serve as reservoirs of resistant bacteria that may spread to humans through direct contact, environmental contamination, or the food chain in the case of horses destined for slaughter. Conversely, horses may acquire resistant organizms from human handlers or from shared environments. This bidirectional flow of resistance determinants means that equine practitioners have a professional responsibility that extends beyond the individual patient to the wider community.

The regulatory landscape for veterinary antimicrobials is evolving in response to these concerns. The [FDA Center for Veterinary Medicine](https://www.fda.gov/animal-veterinary) provides regulatory information on approved animal drugs, labeling, extralabel use, and compounding policy, and practitioners must remain current with these requirements. The [AVMA practice resources](https://www.avma.org/resources-tools) offer additional professional guidance on stewardship implementation. While specific regulatory requirements vary by jurisdiction, the underlying principle is consistent: antimicrobial use in horses must be justified, documented, and aligned with resistance mitigation goals.

## Diagnostic Decision Points in Equine Antimicrobial Use

The first decision point in any equine antimicrobial encounter is whether an antimicrobial is indicated at all. Many common equine conditions, including uncomplicated viral respiratory infections, mild colitis, and superficial wounds without sepsis, do not require systemic antimicrobials. The clinician should establish a presumptive diagnosis, assess the likelihood of bacterial involvement, and determine whether the infection is localized or systemic before prescribing. [Antimicrobial stewardship in equine practice](https://pubmed.ncbi.nlm.nih.gov/31236925/) emphasizes that the same judicious-use mandate applied in human medicine governs equine prescribing decisions.

When bacterial infection is confirmed or strongly suspected, the next decision is empirical versus culture-directed therapy. Empirical therapy is appropriate when the patient is systemically ill, when sampling is impractical, or while culture results are pending. The choice of empirical agent should reflect the most probable pathogen, the infection site, and the drug's pharmacokinetic profile at that site. For example, a penetrating synovial structure requires an agent that achieves therapeutic concentrations in synovial fluid, whereas pneumonia requires agents that penetrate pulmonary tissue and secretions.

Culture and susceptibility testing should be performed whenever the infection is severe, recurrent, refractory to initial therapy, or likely to involve resistant organizms. Samples must be collected before antimicrobial administration whenever possible. The laboratory report should be interpreted with attention to the site of infection, the organizm's known pathogenicity, and whether the isolate represents true infection or contamination. [Antimicrobial prescribing and antimicrobial resistance surveillance in equine practice](https://pubmed.ncbi.nlm.nih.gov/35575046/) reports that many equine veterinarians do not routinely perform culture and susceptibility testing, a gap that perpetuates empirical prescribing and obscures resistance trends.

## Selecting an Antimicrobial Agent

The selection of an antimicrobial agent should follow a structured sequence: identify the likely pathogen, consider the infection site and tissue penetration, review the patient's organ function, and then choose the narrowest-spectrum agent with a favourable safety profile. The table below summarizes common equine infections and first-line antimicrobial considerations. Doses, frequencies, and withdrawal periods must be verified against current formulary and label references before administration.

| Clinical condition | Common bacterial pathogens | First-line antimicrobial considerations | When to escalate or change |
|---|---|---|---|
| Adult pneumonia | *Streptococcus equi* subsp. *zooepidemicus*, *Pasteurella* spp., opportunistic Gram-negatives | Penicillin or potentiated sulfonamide for mild cases, add an aminoglycoside for severe or suspected Gram-negative involvement | Lack of clinical response within 48 to 72 hours, growth of resistant organizm on culture |
| Neonatal sepsis | Gram-negative enterics, *S. equi* subsp. *zooepidemicus*, *Rhodococcus equi* in endemic areas | Broad-spectrum combination therapy, typically a beta-lactam with an aminoglycoside | Culture results indicate resistance, deteriorating clinical status |
| Synovial sepsis | *S. equi* subsp. *zooepidemicus*, *Staphylococcus aureus*, Gram-negative enterics | Beta-lactam with an aminoglycoside, regional limb perfusion may be considered | Positive culture with resistance, no improvement after lavage and initial therapy |
| Superficial wound infection | Beta-hemolytic streptococci, *S. aureus*, *Corynebacterium* spp. | Topical therapy or penicillin for localized infection without systemic signs | Spreading cellulitis, systemic illness, or culture-confirmed resistant pathogen |
| *Rhodococcus equi* pneumonia in foals | *R. equi* | Macrolide with rifampicin is the traditional combination, consult current references for alternatives | Clinical deterioration, macrolide-associated adverse effects, regional resistance patterns |
| Bacterial diarrhea in adults | *Clostridioides difficile*, *Neorickettsia risticii*, *Salmonella* spp. | Antimicrobials are often not indicated, supportive care is primary | Systemic sepsis, neutropenia, or documented bacterial pathogen requiring targeted therapy |

The table reflects general clinical reasoning, not a protocol. Regional resistance patterns, patient age, and concurrent disease modify every choice. For example, an adult horse with uncomplicated diarrhea and no systemic signs should not receive antimicrobials, whereas a neutropenic neonate with suspected sepsis requires immediate broad-spectrum therapy.

## The Role of Diagnostic Testing and Rapid Techniques

Conventional culture and susceptibility testing requires 48 to 72 hours, a delay that often forces continued empirical therapy. Rapid diagnostic techniques, including polymerase chain reaction assays and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry, can identify pathogens within hours. [Antimicrobial stewardship in equine practice](https://pubmed.ncbi.nlm.nih.gov/31236925/) identifies faster and more accurate identification and sensitivity testing as a key opportunity for more effective antimicrobial use. When rapid testing is available, the clinician should use it to narrow therapy earlier instead of continuing broad-spectrum coverage until the conventional report arrives.

Point-of-care testing is not universally available in ambulatory equine practice. The clinician must weigh the cost and turnaround time of each test against the clinical urgency. A stable horse with localized infection can often wait for culture results before starting therapy. A febrile, toxic horse cannot. In the latter case, collect samples, begin empirical therapy, and de-escalate when results return.

## Monitoring the Response to Therapy

Clinical monitoring should follow a defined schedule. The most useful parameters are rectal temperature, heart rate, respiratory rate, mucous membrane color, capillary refill time, appetite, fecal output, and serial examination of the infected site. For pneumonia, thoracic auscultation and serial ultrasonography provide objective evidence of resolution. For synovial sepsis, serial synovial fluid analysis, including total nucleated cell count and protein concentration, guides the duration of therapy.

The clinician should reassess the patient within 48 to 72 hours of starting empirical therapy. Improvement in temperature curve and appetite supports continuing the current agent. Lack of improvement, or deterioration, mandates re-evaluation of the diagnosis, repeat sampling for culture, and consideration of a change in antimicrobial class. [Antimicrobial prescribing and antimicrobial resistance surveillance in equine practice](https://pubmed.ncbi.nlm.nih.gov/35575046/) notes that many practices lack formal audit processes, which limits their ability to identify suboptimal prescribing patterns over time.

Documentation should record the indication for antimicrobial use, the agent selected, the dose and frequency, the planned duration, the culture results when available, and the clinical response at each reassessment. This record supports both individual patient care and practice-level stewardship audits.

## A Practical Stewardship Checklist for Equine Cases

The following checklist condenses the decision framework into a sequence suitable for routine clinical use.

1. Establish a working diagnosis and assess whether bacterial infection is likely.
2. Determine whether the infection is localized or systemic and whether the patient is stable.
3. Collect samples for culture and susceptibility testing before antimicrobial administration when feasible.
4. Select an empirical agent based on the most probable pathogen, tissue penetration, and patient factors.
5. Choose the narrowest-spectrum agent appropriate for the clinical situation.
6. Verify dose, frequency, route, and withdrawal period against current label and formulary references.
7. Document the indication, agent, dose, and planned review date in the medical record.
8. Reassess the patient within 48 to 72 hours using objective clinical parameters.
9. De-escalate or change therapy based on culture results and clinical response.
10. Discontinue antimicrobials when the infection has resolved, not when the prescription bottle is empty.
11. Report suspected adverse drug reactions and therapeutic failures through the appropriate pharmacovigilance pathway, as described in [FDA Center for Veterinary Medicine animal drug information](https://www.fda.gov/animal-veterinary).
12. Review prescribing patterns at the practice level periodically to identify opportunities for improvement.

## Practice-Level Stewardship Systems

Individual prescribing decisions operate within a practice environment that either supports or undermines stewardship. A written antimicrobial use policy is the foundation of a practice-level program. [Antimicrobial prescribing and antimicrobial resistance surveillance in equine practice](https://pubmed.ncbi.nlm.nih.gov/35575046/) found that only about half of surveyed equine practices had such a policy, and over half performed no environmental surveillance. Practices should establish a formulary that designates first-line agents for common conditions, restricts high-priority critically important antimicrobials to culture-confirmed or clinically justified use, and defines the circumstances under which specialist consultation is required.

Client communication is an integral component of stewardship. Owners often expect an antimicrobial prescription for conditions that do not require one. The clinician should explain the rationale for withholding antimicrobials, the risks of resistance, and the expected course of the condition. Written client information sheets can reinforce the verbal discussion. [Antimicrobial stewardship in equine practice](https://pubmed.ncbi.nlm.nih.gov/31236925/) identifies improved client education as a necessary component of more effective antimicrobial use.

Practice-level surveillance should include periodic review of antimicrobial purchases, prescription records, and culture results. This audit identifies trends such as increasing use of a particular agent or rising resistance in a common pathogen. The [AVMA antimicrobial use and stewardship resources](https://www.avma.org/resources-tools/one-health/antimicrobial-use-and-antimicrobial-resistance) provide guidance on establishing these systems within a practice. International standards, including the [WOAH terrestrial animal health code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/), frame these local efforts within a global surveillance context.

## Recognized Complications and Early Detection

The most consequential failure mode in equine antimicrobial therapy is the selection of resistant organizms during treatment. This occurs when an antimicrobial eliminates susceptible flora while resistant subpopulations proliferate, often in the gastrointestinal tract or at the site of infection. Early detection relies on serial clinical assessment instead of on any single laboratory value. A horse that improves for 48 to 72 hours and then deteriorates, or one that never improves despite appropriate drug selection, warrants repeat sampling for culture and susceptibility testing. Fever that persists beyond 72 hours of therapy, worsening synovial fluid parameters in joint cases, or increasing peritoneal fluid nucleated cell counts all indicate treatment failure and demand re-evaluation of the isolate and the drug regimen.

A second recognized complication is antimicrobial-associated diarrhea. Horses receiving macrolides, clindamycin, or high-dose potentiated sulphonamides are at particular risk, although any antimicrobial can disturb the hindgut microbiota. Early detection depends on daily fecal consistency assessment and monitoring for systemic signs such as tachycardia, injected mucous membranes, or prolonged capillary refill time. The clinician should distinguish simple softening of feces, which may resolve with continued therapy, from profuse watery diarrhea with systemic compromise, which requires immediate drug discontinuation and supportive care.

A third failure mode is the development of injection-site reactions or phlebitis from repeated parenteral administration. These complications are often detected late because swelling may be subtle in heavily muscled horses. Daily palpation of injection sites and inspection of catheterized veins for heat, pain, or thrombus formation allows early intervention. Changing administration routes or rotating sites reduces the risk of abscessation and subsequent multidrug-resistant wound infections.

## Common Errors and Corrective Action

Less experienced clinicians frequently underdose beta-lactam antimicrobials, particularly procaine penicillin. Survey data from Australian veterinary practice found that 68% of respondents reported procaine penicillin doses in horses that were unlikely to achieve plasma concentrations above the minimum inhibitory concentrations for common equine pathogens. The corrective action is to consult current formulary references and label information instead of relying on habitual dosing, and to recognize that penicillin is time-dependent in its killing activity, requiring adequate dosing frequency as well as dose magnitude.

A second common error is the reflexive use of broad-spectrum antimicrobials when a narrow-spectrum agent would suffice. Third-generation cephalosporins were the most commonly prescribed systemic antibiotic class in a survey of Minnesota and North Dakota practices. The corrective action is to identify the most likely pathogen from the clinical context, select the narrowest agent with predicted efficacy, and de-escalate once culture results return.

A third error is treating antimicrobial therapy as a substitute for source control. Draining an abscess, removing a foreign body, or lavaging a septic joint is often more important than the drug chosen. The corrective action is to ask whether the infection can be physically addressed before writing the prescription.

| Observation | Likely Cause | Discriminating Check |
|---|---|---|
| Fever persists beyond 72 hours | Resistant isolate, undrained focus, or wrong drug | Repeat culture and susceptibility, re-imaging of the primary site |
| Deterioration after initial improvement | Selection of resistant subpopulation | Repeat sampling, review susceptibility results |
| Soft feces during therapy | Mild hindgut disturbance | Monitor frequency and hydration, continue if systemic signs are normal |
| Profuse watery diarrhea with tachycardia | Antimicrobial-associated colitis | Discontinue drug, initiate supportive care, consider toxin testing |
| Swelling at injection site | Tissue reaction or abscess | Palpate daily, ultrasound if fluctuant, switch route if progressive |

## Limitations of the Evidence and Divergent Expert Opinion

The evidence base for equine antimicrobial stewardship remains thin. There is limited information on the epidemiology of antimicrobial-resistant bacterial infections in horses, and much of what exists derives from referral hospital populations instead of ambulatory practice. Whether these data generalize to first-opinion caseloads is uncertain. Expert opinion also differs on the acceptability of prophylactic antimicrobial use in clean elective surgery, with some authorities endorsing a single perioperative dose and others recommending none. The duration of therapy for common infections such as pneumonia or synovial sepsis is likewise contested, with recommendations ranging from five days to several weeks based largely on tradition instead of comparative trials.

Regulatory frameworks vary substantially between jurisdictions. The US Food and Drug Administration provides oversight of approved animal drugs and extralabel use policy, while the World Organization for Animal Health publishes international standards for antimicrobial use and resistance surveillance. Practitioners must know which rules apply in their own region and recognize that guidance from one country may not be lawful elsewhere.

## Referral, Consultation, and Reporting

Referral is warranted when the clinician lacks the diagnostic capacity to identify the pathogen, when the infection involves a structure whose outcome depends on specialised care such as the eye, joint, or pleural cavity, or when the horse fails to respond to first-line therapy. Specialist consultation is appropriate for recurrent infections, suspected multidrug-resistant organizms, and cases where antimicrobial choices are constrained by drug availability or withdrawal requirements. Laboratory involvement extends beyond culture and susceptibility to include minimum inhibitory concentration testing for isolates from deep infections, therapeutic drug monitoring for aminoglycosides, and molecular typing when outbreaks are suspected.

Regulatory reporting obligations vary by region. Suspected adverse drug reactions, including lack of efficacy, should be reported through the relevant national pharmacovigilance system. Detection of notifiable organizms, where these exist, or unusual resistance patterns with public health implications may trigger reporting obligations under [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). The equine practitioner should maintain a working relationship with their national veterinary authority and with [AVMA antimicrobial stewardship resources](https://www.avma.org/resources-tools/one-health/antimicrobial-use-and-antimicrobial-resistance) to remain current on reporting expectations.

## Frequently Asked Questions

### How Do I Prioritize Stewardship When My Practice Lacks Rapid Diagnostics or On-Site Culture Facilities?

When rapid diagnostics are unavailable, base initial therapy on the most likely pathogen, infection site, and local susceptibility patterns. Collect samples for culture and susceptibility testing before starting therapy whenever sampling is feasible, even if the laboratory is remote. Send samples by courier with appropriate transport media. Empirical regimens should use the narrowest spectrum agent expected to be effective, and therapy should be reassessed once results return. Practices without in-house laboratories can still audit prescribing patterns manually or through practice management software. The same stewardship principles apply regardless of facility size, and [published guidance on antimicrobial stewardship in equine practice](https://pubmed.ncbi.nlm.nih.gov/31236925/) emphasizes that diagnostic capacity, not commitment, is the usual limiting factor.

### What Should I Record for a Meaningful Antimicrobial Use Audit?

Record the drug, dose, route, frequency, duration, indication, and whether culture and susceptibility testing was performed. Note the clinical response and any adverse events. Record whether the prescription was initial, revised, or continued therapy. For audits to be useful, record the reason for drug selection, especially when a broader-spectrum agent is chosen. Review these records quarterly to identify trends, such as excessive use of a particular drug class or prolonged durations for post-operative prophylaxis. [Survey data from equine practitioners in the UK and Europe](https://pubmed.ncbi.nlm.nih.gov/35575046/) found that only about half of practices had a written antimicrobial policy, and routine audit was uncommon. A simple spreadsheet is sufficient to start, and the act of recording often changes prescribing behavior.

### How Do I Discuss Antimicrobial Resistance With a Client Who Demands Antibiotics for a Viral Infection?

Explain that antibiotics treat bacterial infections and do not shorten the course of viral disease. Describe the difference between infection and inflammation, and explain that giving an unnecessary antibiotic selects for resistant bacteria that may colonise the horse and its environment. Frame the decision as protecting the horse's future treatment options. Offer a concrete alternative, such as anti-inflammatory therapy, nursing care, or a recheck examination in 48 hours. Provide written aftercare instructions. [The economic importance of the equine industry and the consequences of resistant infections for horse health and trade](https://pubmed.ncbi.nlm.nih.gov/39200013/) give clients a tangible reason to accept conservative prescribing. Most owners respond well when the clinician frames stewardship as a welfare and biosecurity issue instead of a cost-saving measure.

### When Is It Acceptable to Use a Higher-Priority Antimicrobial as First-Line Therapy?

Higher-priority agents are acceptable when culture and susceptibility results show that no narrower agent is effective, when the infection is life-threatening and delay for culture results would endanger the patient, or when pharmacokinetic properties make a narrower agent ineffective at the infection site. Document the rationale in the medical record. For critically ill neonates or adult horses with suspected gram-negative sepsis, initial broad-spectrum therapy is justified, but de-escalation should occur as soon as culture results permit. [The emergence of extended-spectrum beta-lactamase-producing organizms in companion animals](https://pubmed.ncbi.nlm.nih.gov/21462862/) highlights why reserve agents must be protected. If higher-priority drugs are used empirically, review the case daily and narrow therapy at the earliest safe point.

### How Should I Handle Antimicrobial Prescribing When Treating a Horse That Will Enter the Human Food Chain?

Horses intended for slaughter for human consumption require careful attention to withdrawal times and extralabel use regulations. Consult the current label and regulatory guidance before prescribing any antimicrobial for a food animal, and document the withdrawal interval you assign. Extralabel use of certain drugs is prohibited in food-producing animals, and the responsible veterinarian must establish a valid veterinarian-client-patient relationship before prescribing. [Regulatory information on approved animal drugs and extralabel use policy](https://www.fda.gov/animal-veterinary) is the appropriate reference for US practitioners, while international colleagues should consult their national authority and [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). When in doubt, choose a drug with a well-characterized residue profile and communicate the withdrawal period to the owner in writing.

### What Do I Do When a Colleague or Referring Practice Routinely Prescribes Broad-Spectrum Antimicrobials Inappropriately?

Address the issue directly but collegially, focusing on the clinical case instead of the individual. Ask what clinical findings led to the drug choice and whether culture was considered. Offer to review the case together and share any practice-level guidelines you use. If the prescribing occurs within your practice, raise the topic at a clinical meeting and propose a simple audit of antimicrobial use. [Professional guidance on judicious antimicrobial use](https://www.avma.org/resources-tools/one-health/antimicrobial-use-and-antimicrobial-resistance) supports practice-level discussion as a legitimate stewardship activity. If the behavior continues and patient welfare is compromised, escalate through practice management or professional regulatory channels. Avoid public criticism of colleagues in front of clients, as this undermines trust in the profession and does not improve prescribing.

## Related Clinical & Scientific Guides

* [Veterinary Formulary Essentials: Navigating Drug References](/knowledge/veterinary-medicine/clinical-pharmacology/veterinary-formulary-essentials-navigating-drug-references)
* [Drug Interactions with Antiepileptic Drugs in Veterinary Patients: Managing Polypharmacy](/knowledge/veterinary-medicine/clinical-pharmacology/drug-interactions-antiepileptic-veterinary)
* [Drug Interactions with Corticosteroids in Veterinary Patients: A Comprehensive Review](/knowledge/veterinary-medicine/clinical-pharmacology/drug-interactions-corticosteroids-veterinary-comprehensive)


## References and Further Reading

- [Antimicrobial Resistance in Equines: A Growing Threat to Horse Health and Beyond-A Comprehensive Review.](https://pubmed.ncbi.nlm.nih.gov/39200013/). 2024.
- [A quarterly Survey of antibiotic prescribing in small animal and equine practices-Minnesota and North Dakota, 2020.](https://pubmed.ncbi.nlm.nih.gov/35643964/). 2022.
- [Extended-spectrum beta-lactamases-producing gram-negative bacteria in companion animals: action is clearly warranted!](https://pubmed.ncbi.nlm.nih.gov/21462862/). 2011.
- [Antimicrobial stewardship in equine practice.](https://pubmed.ncbi.nlm.nih.gov/31236925/). 2019.
- [Antimicrobial prescribing and antimicrobial resistance surveillance in equine practice.](https://pubmed.ncbi.nlm.nih.gov/35575046/). 2023.
- [Antimicrobial labeling in Australia: a threat to antimicrobial stewardship?](https://pubmed.ncbi.nlm.nih.gov/29691852/). 2018.
- [FDA Center for Veterinary Medicine: Animal Drug Information](https://www.fda.gov/animal-veterinary). FDA CVM.
- [AVMA Antimicrobial Use and Stewardship](https://www.avma.org/resources-tools/one-health/antimicrobial-use-and-antimicrobial-resistance). American Veterinary Medical Association.
- [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual.

## Related Articles

- [Antimicrobial Stewardship in Small Animal Practice: Implementing a Program](/knowledge/veterinary-medicine/clinical-pharmacology/antimicrobial-stewardship-small-animal-practice-implementing-program)
- [Antimicrobial Stewardship in Equine Respiratory Disease: Evidence-Based Use](/knowledge/veterinary-medicine/clinical-pharmacology/antimicrobial-stewardship-equine-respiratory-disease-evidence-based)
- [Antimicrobial Stewardship in Food Animals: Principles and Practical Application](/knowledge/veterinary-medicine/clinical-pharmacology/antimicrobial-stewardship-food-animals-principles-practical-application)
- [Antimicrobial Stewardship in Food Animals: Withdrawal Times and Residue Avoidance](/knowledge/veterinary-medicine/clinical-pharmacology/antimicrobial-stewardship-food-animals-withdrawal-times-residue-avoidance)
- [Antimicrobial Stewardship in Respiratory Infections of Dogs and Cats](/knowledge/veterinary-medicine/clinical-pharmacology/antimicrobial-stewardship-respiratory-infections-dogs-cats)

> 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.