Respiratory

Antimicrobial Survey Shows Equine Asthma Knowledge Gap, Need for Clear Guidelines

By Paul Basilio

More than half of equine veterinarians reported prescribing antimicrobials in patients with asthma, signaling a need for increased focus on antimicrobial stewardship, acording to a recent study.

Resistant bacteria can cause difficult-to-treat infections in both humans and animals, and the minimization and optimization of antimicrobial use is critical to prevent further resistance.
Equine asthma is not considered an infectious respiratory disease, and as such, antimicrobials are not normally an effective treatment. Results of the survey, published recently in the journal Animals, indicate a knowledge gap and the need for clear, worldwide guidelines on antimicrobial stewardship to diminish the use of critically important antimicrobials.

“As veterinarians, we should be aware that we not only have a responsibility to our equine patients, but also to public health,” said Astrid J. van den Brom-Spierenburg, DVM, DECEIM, EBVS, of the University of Utrecht in the Netherlands and lead author of the study, in an interview with Modern Equine Vet.

Methods
Investigators distributed an online survey in 6 languages from December 2020 through January 2022. Of the 434 responses, 249 veterinarians working in 25 countries responded, including 79 American College of Veterinary Internal Medicine/European College of Equine Internal Medicine diplomates.
Most respondents were female (74%); 36% were in practice for 0 to 10 years, 36% for 11 to 20 years, and 28% for more than 20 years. The largest proportion of respondents (77%) were equine veterinarians, with more than 95% of their patients being equids. Slightly more than half (51%) were in first-opinion practices (FOPs), 26% worked in academia, 13% worked in a private referrThe survey consisted of several parts:

• Informed consent form and questions concerning career length, percentage of equine patients in the practice, country, etc.
• 10 questions regarding the definition and pathophysiology of equine asthma, as presented in the last revised consensus statement.
• 3 case studies representing severe, mild and moderate equine asthma, respectively.
• Respondents were asked to define the cases using correct terms such as severity and type of asthma, or older terms such as recurrent airway obstruction (RAO) or inflammatory airway disease (IAD).
• Respondents were then asked to select the factors that would influence their decision about whether to use antimicrobials.

Survey Says…
Overall, 82% of respondents reported awareness of national regulations concerning antimicrobial use in their country, and 46% of respondents reported practice guidelines concerning antimicrobial use. Most felt guided by the national regulations and practice guidelines (78% and 82%, respectively), but some felt limited by such guidelines (36% and 23%, respectively).

In at least 1 of the 3 asthma case studies, 53% of the respondents said they had use antimicrobials at least “sometimes” in similar cases, with the leading antimicrobials being trimethoprim-sulfamethoxazole (N=105), penicillin (N=53) and tetracyclines (N=38). Further analysis revealed that tetracyclines and cephalosporins were prescribed more often by veterinarians working in areas without national regulations.

“It was good to see that most veterinarians using antimicrobials in these cases said they use them only ‘sometimes,’” Dr. van den Brom-Spierenburg said. “That made me even more curious to find out what people base their decisions on. Knowing that [answer] would be the point to go from if you’d want to change the prescription behavior.”

The survey also identified some knowledge gaps regarding equine asthma. For example, 13 veterinarians reported using laboratory blood analysis in a patient with presentation and signs consistent with asthma, although changes in the peripheral blood would not be expected in such patients. However, Dr. van den Brom-Spierenburg wondered if these veterinarians were concerned about missing another condition, such as a possible pneumonia, which could have similar signs. Increased knowledge and more advanced diagnostics like endoscopy and bronchoalveolar lavage (BAL) might improve their diagnostic certainty.

Regarding the questions about asthma knowledge, the median number of correct answers was 6 of 10 (interquartile range [IQR], 4-9). The diplomates answered the highest proportion of questions correctly (9 of 10; IQR, 8-10), followed by respondents in private referral clinics (8 of 10; IQR, 7-9) and FOPs (4 of 10; IQR, 7-9). There were no apparent differences among groups with different career lengths.

More than half of respondents (57%) somewhat or strongly agreed with the statement, “I assume an important role for fungi in some equine asthma cases.” For similar statements regarding viruses and bacteria, 44% and 25% agreed, respectively.

Knowledge of the definition of asthma as presented in the revised ACVIM consensus statement was greater in veterinarians whose practice involved mostly equine patients compared with veterinarians working in a mixed-veterinary practice.

“When we asked why people would prescribe antimicrobials, non-medical factors like ‘the owner wants me to prescribe antimicrobials’ were selected only rarely,” Dr. van den Brom-Spierenburg said. “This means veterinarians were mainly driven by their own intrinsic veterinary considerations for the patients. I think that is good news, since non-medical factors—meaning more social reasons—probably would be harder to change with just education.

She added that it was surprising to find no associations between antimicrobial prescription in asthma and time in practice.

“At our veterinary college we discuss antimicrobial use in all types of patients with our students, which I think is a trend worldwide,” she said. “Therefore, we expected the younger colleagues to prescribe fewer antimicrobials when compared with their older colleagues. Our survey, however, showed no differences between the experienced versus the more recently graduated vets, nor in their knowledge on the pathophysiology of asthma, nor in their prescription behavior.” MeV

For more information:
van den Brom-Spierenburg AJ, Muresan AN, Westermann CM. Antimicrobial prescription behavior in equine asthma cases: an international survey. Animals. 2024;14(3):457.
https://www.mdpi.com/2076-2615/14/3/457