Pancytopenia in two horses following administration of potentiated sulfonamide antimicrobials

Abstract

Summary Adverse drug reactions to potentiated sulfonamide antimicrobial drug combinations have been reported in many species, including horses. This report describes the occurrence of pancytopenia in 2 horses, one subsequent to an immune mediated reaction and the other bone marrow aplasia following the administration of trimethoprim and sulfadimidine. These cases highlight the importance of judicious use of antimicrobial agents and describe adverse drug reactions in horses receiving potentiated sulfonamide antimicrobials.

Pancytopenia in horses

“…Such reactions, are unrelated to dose or duration of exposure (the limitation being the time needed to produce antibodies) and as such are largely unpredictable. The horses reported here by Cudmore et al (2015) experienced an allergic or 'hypersensitivity' response as previously described in dogs (Trepanier et al 2003), is supported by the multiple cell types, including thrombocytes, targeted in the bone marrow. What is less clear is why the bone marrow is often a target of presumed haptenisation by sulfonamides or other drug allergens.…”

“…The horses reported here by Cudmore et al . () experienced an allergic or ‘hypersensitivity’ response as previously described in dogs (Trepanier et al . ), is supported by the multiple cell types, including thrombocytes, targeted in the bone marrow.…”

Immuungemedieerde hemolytische anemie geassocieerd met chronisch fibroserende mediastinitis bij een Arabo-Fries paard

“…This has been reported after administration of certain drugs. Several cases associated to penicillin (Blue et al, 1987;Step et al, 1991;McConnico et al, 1992;Robbins et al, 1993) and potentiated sulfonamides have been documented in horses (Thomas and Livesey, 1998;Brumbaugh, 2001;Stockham and Scott, 2008;Cudmore et al, 2015;Dunkel, 2018). Certain infectious agents can induce secondary IMHA, e.g.…”