Expert Q & A

Interview with Dr. Amelia Sidwell

By Adam Marcus

Equine veterinarians frequently find themselves looking sick horses in the mouth. But whether and when to use antibiotics for equine dental concerns is not always immediately clear.

The Modern Equine Vet spoke with Amelia Sidwell, DrMedVet, of the University of Nottingham, England, and lead author of a recent review article on the topic, about best practices, things to avoid and more.

MEV: You and your colleagues suggest targeted antibiotic therapy may be justified in high-risk cases such as systemic illness or severe infection. What specific clinical or diagnostic red flags, such as particular hematology values, the presence of fever or radiographic evidence of extensive osteomyelitis, should veterinarians use to call a horse “high-risk” rather than a routine case in which antibiotics can be safely omitted?

Dr. Sidwell: Antibiotics are not indicated for routine dental infections, but they may be appropriate where there is evidence of systemic illness, more extensive infection, or impaired host defenses and compromised ability to respond to infection. Crucially, the distinction must be made between localized dental pathology and situations where infection is no longer localized.
Clinical features that may justify classifying a case as ‘higher-risk’ include:

• Pyrexia: The presence of fever suggests a systemic inflammatory response rather than a purely localized process. In these cases, clinicians should carefully consider whether it is appropriate to proceed with elective procedures before the patient is stabilized.
• Evidence of systemic illness: Depression, inappetence, or other signs of systemic compromise may indicate that the disease process extends beyond the tooth and supporting structures.
• Hematologic abnormalities: While mild to moderate neutrophilia or changes in inflammatory biomarkers can be seen with local inflammation, they are relatively nonspecific.
• Greater concern should be given to neutropenia, which may indicate overwhelming infection or reduced immunocompetence, and marked inflammatory changes (eg, toxic neutrophils) and significant increases in inflammatory markers (ie, serum amyloid A values >1,000 mg/L) that often correlate with acute infectious processes. However, these changes are nonspecific and would be atypical for routine dental or sinus disease alone. Their presence should prompt a broader clinical assessment for concurrent or alternative pathology.
• Extensive local disease, such as osteomyelitis: Radiographic or advanced imaging evidence of chronic osteomyelitis as a sequela to dental disease, trauma, or placement of surgical implants is one of the clearer indications for more prolonged antibiotic therapy. In these cases, treatment protocols are often extrapolated from the small-animal and human literature, where antimicrobials are used adjunctively with surgical debridement of infected bone.
• Immunocompromised patients: Horses with conditions such as uncontrolled pituitary pars intermedia dysfunction or other causes of impaired immune function may be less able to contain infection
  and, therefore, represent a higher-risk group.

It is important to emphasize that, even in high-risk cases, antibiotic use is adjunctive, not curative. Definitive treatment relies on addressing the underlying cause.

MEV: You emphasize that surgical intervention, like exodontia, is the primary approach and that antibiotics should not replace it. In cases of confirmed dental infection, can pretreating the horse with a course of antibiotics prior to extraction improve surgical outcomes or reduce the bacterial load significantly enough to justify the delay, or should clinicians proceed immediately to surgery without any medical prep?

Dr. Sidwell: Surgical intervention, such as exodontia, remains the definitive treatment for equine dental infections, and there is currently no evidence to support the routine use of antibiotics to improve surgical outcomes or meaningfully reduce bacterial load prior to extraction.

In cases of apical infection or endodontic disease, antibiotics do not address the underlying pathology. As such, they should not be used as a substitute for timely surgical intervention, nor is there any existing evidence that pre-treating with antibiotics improves success rates or reduces postoperative complications.

Conversely, delaying surgery to administer antibiotics may simply prolong disease and discomfort without providing clinical benefit. The priority should therefore be to proceed with definitive treatment where feasible, with analgesic and/or anti-
inflammatory medication provided in the meantime.

An important exception is in horses with dental-related sinusitis or evidence of infection extending to surrounding tissues, where uncontrolled infection could compromise patient welfare—for example, in situations with an unavoidable delay between diagnosis and treatment. These cases may show temporary clinical improvement with antibiotics. However, this should be clearly framed as a holding measure rather than a cure, as recurrence is expected without addressing the underlying cause. Clinicians must avoid situations in which repeat courses of antibiotics are prescribed, as delays in treatment are associated with poorer clinical outcomes.

Overall, antibiotics should be reserved for cases that meet clear clinical criteria and should not be used routinely to ‘optimize’ surgical outcomes when evidence does not support their benefit.

MEV: Since rates of postoperative infection after dental procedures are low—less than 20%—even without antibiotics, veterinarians may feel pressure to prescribe simply to be safe. What standardized postoperative monitoring protocols—routine temperature checks, incision site assessments, monitoring breath—can clinicians offer owners to help avoid antibiotics unless a specific complication arises?

Dr. Sidwell: Active monitoring is safer than routine antibiotics in most low-risk equine dental cases. To provide reassurance, clients should be given clear, structured postoperative instructions, along with confirmation of who their out-of-hours veterinary provider is in the unlikely event that complications arise, particularly if this is not the clinician performing the procedure. Clear escalation triggers that help them recognize ‘when to call’ are essential. Clients should be advised to monitor for:

• Changes in temperature (where safe and feasible), which may indicate early systemic inflammation or developing infection
• Alterations in appetite or eating behavior (eg, slower eating, quidding), which are often sensitive indicators of oral discomfort
• Abnormal discharge from the surgical site (eg, following minimally invasive transbuccal extraction or sinus osteotomy) or from the nose, especially if unilateral and malodorous
• Development of facial swelling
• Halitosis, which may suggest localized infection or feed impaction
• Behavioral changes, which are often early and underappreciated indicators of complications, including:
   ■ General dullness, which could reflect pyrexia or (rarely) postprocedural colic
   ■ Repeated facial rubbing, which can occur with altered sensation following perineural anesthesia
   ■ Atypical jaw movements or chewing patterns

However, it is also important to help owners recognize that some mild postoperative changes are expected and normal, and to be explicit about what owners do not need to do. For example, examination of the equine oral cavity is generally unsafe and impractical for owners, except in very limited cases (eg, incisor or canine pathology). Instead, emphasis should be placed on observable external and behavioral indicators.

Crucially, the trajectory of recovery is more informative than any single sign, and horses should show steady improvement over time. Therefore, scheduling a routine re-examination is essential to assess healing and to inspect the surgical site, including the alveolus following exodontia. Scheduled follow-up helps reduce client anxiety and therefore pressure to prescribe antibiotics ‘just in case.’
It is also important to recognize that the most common complication following exodontia is sequestration. Antibiotics are not curative in these cases. Management instead should focus on appropriate analgesia and allowing sequestra to mature prior to removal.

MEV: As with human patients, the paper identifies “satisfying client expectations” and “fear” as major non-clinical drivers for antibiotic use. What are some effective evidence-based talking points clinicians can use to explain to a concerned client that giving precautionary antibiotics may pose a greater risk to their horse—specifically regarding disruption of the gastrointestinal microbiome—than the low risk for a postoperative dental infection?

Dr. Sidwell: Reassuring clients that, in most equine dental procedures, the risk of postoperative infection is very low and that these conditions are typically not life threatening. By contrast, antibiotic use is not risk-free in horses, which rely on a highly specialized gastrointestinal microbiome to digest food. Antibiotics can disrupt that balance, with potentially fatal consequences. Complications associated with dental procedures can be addressed if and when they arise, but we cannot immediately reverse disruption to the microbiome once it has occurred.

The same principles are followed in responsible human healthcare: antibiotics are no longer routinely given ‘just in case’, as the risks—both to the individual patient and to antimicrobial resistance—often outweigh the benefits.

Taking the time to reassure clients that you are not withholding care by withholding antibiotics is the safest option for their horse, in line with current best-practice evidence, after performing a calculated risk-benefit assessment tailored to each unique clinical scenario.

MEV: Beyond the obvious risk of antibiotic-associated colitis, how does a short course of perioperative antibiotics affect the long-term health of the equine oral microbiome? Could this disruption paradoxically make the horse more susceptible to future periodontal disease or other systemic issues?”

Dr. Sidwell: There is currently insufficient evidence to conclusively demonstrate the impact of antibiotics on the oral microbiome and links with disease prevalence. However, antibiotic use reduces overall microbiome diversity and could contribute to dysbiosis, with shifts in the oral microbiome linked to certain dental disorders in horses.

There is extensive evidence in humans that the oral microbiome shifts following antibiotic use, which can remain altered for many months. The development of oral candidiasis is a known sequela of antibiotic use in humans due to this disruption in the normal oral flora.

While not related to the oral microbiome, the association between the development of fungal sinusitis and prolonged antimicrobial use in horses would suggest that disruption of the normal microbiome within the equine upper respiratory tract permits fungal microorganisms to flourish. MeV

FOR MORE INFORMATION
Sidwell A, Hole SL, Pereira R. Antibiotic use in equine dentistry: What is the evidence? Equine Vet Ed 2026;38(5):161-169.