Anaphylactoid reaction caused by sodium ceftriaxone in two horses experimentally infected by Borrelia burgdorferi.
Authors: Basile Roberta Carvalho, Rivera Gabriela Gomes, Del Rio Lara Antoniassi, de Bonis Talissa Camargo Mantovani, do Amaral Gabriel Paiva Domingues, Giangrecco Edson, Ferraz Guilherme, Yoshinari Natalino Hajime, Canola Paulo Aléscio, Queiroz Neto Antonio
Journal: BMC veterinary research
Summary
# Editorial Summary Borrelia burgdorferi infection in horses can precipitate a range of clinical manifestations including lameness, arthritis and neurological signs, yet treatment with sodium ceftriaxone—a commonly used third-generation cephalosporin—carries an underrecognised risk of severe adverse reaction. Two experimentally infected horses in this Brazilian study developed anaphylactoid responses characterised by histamine and arachidonic acid metabolite release following ceftriaxone administration, demonstrating that this antibiotic class can trigger life-threatening inflammatory cascades in the equine species. Whilst anaphylactoid reactions differ from true anaphylaxis in mechanism (direct mediator release rather than IgE-mediated), their clinical severity and potential fatality remain equivalent, making recognition and management critical during treatment of equine borreliosis. The findings highlight an important gap in the documented adverse effect profile of cephalosporins in horses and suggest that practitioners should maintain heightened vigilance for signs of systemic inflammatory response—including respiratory distress, cardiovascular instability and cutaneous reactions—when administering sodium ceftriaxone, particularly in animals with active spirochete infection. Further investigation into alternative antimicrobial strategies and the immunological basis of cephalosporin sensitivity in this population would help refine treatment protocols for tick-borne borreliosis whilst minimising iatrogenic risk.
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Practical Takeaways
- •Be aware that sodium ceftriaxone can trigger severe anaphylactoid reactions in horses, particularly those infected with Borrelia burgdorferi; have emergency equipment and medications available when administering this antibiotic
- •Monitor treated horses closely for signs of anaphylactoid reaction (shock, respiratory distress, cardiovascular collapse) during and after ceftriaxone administration
- •Consider alternative antibiotics for treating equine Lyme borreliosis when anaphylactoid risk is a concern
Key Findings
- •Two experimentally infected horses developed anaphylactoid reactions following sodium ceftriaxone administration
- •Anaphylactoid reactions in horses are mediated by inflammatory mediators including histamine, kinins, and arachidonic acid metabolites
- •Kinins and arachidonic acid metabolites are the most clinically relevant inflammatory mediators in equine anaphylactoid reactions