The discovery, development, clinical use, and introduction of antimicrobials into human and veterinary medicine as well as food animal and plant production transformed the management of infectious diseases in the 20th century. Critically, antimicrobials significantly improved the quality of human and animal life. Apart from the effective treatment of bacterial and fungal infections, the effect of antimicrobials is also reflected in increasing meat production yields that have helped feed the growing human population. Now, the availability of antimicrobials is practically taken for granted by everyone born after the Second World War.
Sadly, the injudicious, widespread overuse of antimicrobials in human and veterinary medicine has led to a precipitous decline in their effectiveness due to rapidly spreading antimicrobial resistance among pathogens. This threat is making antimicrobials ineffective at controlling infectious diseases in human and animal patients. According to the United Nations Environment Health Programme document “Environmental Dimensions of Antimicrobial Resistance,” “Antimicrobial resistance (AMR) is already a leading threat to global health and risks adversely affecting the environmental sustainability of the planet.”
Antimicrobial Resistance Necessitates a New Approach to Equine Infectious Disease Management
Equine infectious disease management will now require adopting strategies to mitigate the indiscriminate use of antibiotics and antifungal medicines for the prophylaxis of infections. The horse-owning public and veterinarians can no longer expect or dispense antimicrobials without evidence that an infection is caused by organisms that are confirmed to be sensitive to a specific antimicrobial treatment. Clinical investigation and diagnostic procedures must be aided by the appropriate laboratory investigations and antimicrobial sensitivity testing. In practice, the dilemma is that this approach is slower than a rapidly progressing infection. The judicious use of a broad-spectrum antibiotic until microbial culture and sensitivity results are available can then be a first treatment step.
The time-limiting factors for the clinician are:
- Rapid access to clinical pathology laboratory facilities, and
- Requesting the appropriate tests based on a horse’s or herd’s clinical presentation and symptoms (laboratory professionals often can help guide these requests).
Best Practices for Equine Management and Husbandry
Going forward, animal management and husbandry must be based on best-practice biosecurity, stable and personal hygiene, animal movement, vaccination strategies, and understanding immune system responses. Rapid recognition of developing infections is an essential part of good horsemanship. This means a return to more intense monitoring of individual horses and herd behavior patterns. As in the pre-antimicrobial era, being more in tune with changes in horses’ appetite and attitude, as well as daily monitoring of rectal temperatures to identify early signs of illness, is necessary. Furthermore, when dealing with both accidental and postsurgical wounds, appropriate topical wound management strategies limit the need for antibiotics. Most cuts and abrasions don’t need “antibiotic cover.”
Within the equine industry, broodmare and young stock practices have been a major culprit for the indiscriminate and liberal use of large amounts of antibiotics. Critically, strategies to limit antimicrobial use to confirmed cases of post-breeding bacterial endometritis in susceptible mares rather than for general prophylaxis has resulted in a welcome reduction in usage without a discernible impact on per-mare cycle conception rates. Additionally, treating healthy newborn foals with a course of prophylactic antibiotics is not necessary and should be reserved for use following the appropriate diagnostic procedures to treat sick foals. Likewise, the risk of developing respiratory disease (“shipping fever”) during and following transportation is not decreased by a course of “preventive” antibiotics. Rather, best practice is to ensure the horse is healthy prior to travel and closely monitored for a minimum of three days at its destination. The larger risk is that horses treated inappropriately prior to travel will develop resistant strains of pathogens, narrowing the choice of antibiotics for effective treatment when they are truly necessary.
New Guidelines for Antimicrobial Use in Horses
National and international veterinary associations are implementing guidelines for the responsible stewardship of antimicrobials in horses in response to the United Nations’ One Health recommendations. These include the British Equine Veterinary Association’s “Protect Me Toolkit,” which encourages veterinarians to implement antimicrobial stewardship strategies.
The response to the program has reduced the use of antibiotics significantly without detriment to the horses in the care of a large general and referral equine practice in Newmarket during the last 10 years. While this progress in antibiotic stewardship by equine practices in the U.K. has been substantiated by a recent study highlighting both improvement and deficiencies in its implementation, there is still much room for improvement. Taking responsibility for the implementation of antibiotic stewardship policies requires continuous critical monitoring of drug usage, behaviors, and trends as well as ongoing education of veterinary professionals and their clients.
Final Thoughts
To protect our ability to manage infectious disease in animals and humans now and in the future, strict antimicrobial stewardship is essential. This is our collective responsibility for all involved in this very diverse global equine industry.
Related Reading
- Equine Pathogens’ Susceptibility to Different Wound Dressings
- Using Absorbable Antibiotic Beads to Treat Infected Wounds in Horses
- Antimicrobial Stewardship With Honey
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