C pseudotuberculosis infections most often cause external abscesses (often in the pectoral and ventral abdominal regions) or ulcerative lymphangitis (infection of lower limbs). This condition occurs commonly in the Southwest although the area of occurrence is expanding. If external lesions do not resolve or the horse becomes systemically ill, this can indicate systemic infection that will require medical therapy. Internal abscesses may develop in abdominal organs (liver, spleen, and kidney) or cause pneumonia. Long-term antimicrobial therapy is usually necessary to resolve the infection.
Links to section in MVM:
Overview of C pseudotuberculosis infection.
References
Rhodes DM, Madgesian KG, Byrne BA, et al: Minimum inhibitory concentrations of equine Corynebacterium pseudotuberculosis isolates (1996-2012). J Vet Intern Med 2015;29(1):327-332. doi:10.1111/jvim.12534
Norman TE, Batista M, Lawhon SD, et al: In vitro susceptibility of equine-obtained isolates of Corynebacterium pseudotuberculosis to gallium maltolate and 20 other antimicrobial agents. J Clin Microbiolol 2014; 52(7):2684-2685. doi:10.1128/JCM.01252-14
Pratt SM, Spier, SJ, Vaughn B, et al: Evaluation of the clinical characteristics and diagnostic test results in horses with internal infection caused by Corynebacterium pseudotuberculosis: 30 cases (1995-2003). JAVMA 2005;227(3):441-448. PMID:16121612