ABSTRACT
Purpura hemorrhagica in horses is most frequently associated with infection by Streptococcus equi, the syndrome can occur with other diseases in which there is an antigen excess with circulating antibodies present. The pathogenesis of purpura hemorrhagica also involves similar immune mechanisms to that of systemic lupus erythematosus (SLE). This chapter presents the case study of country girl. Country Girl is a three-year-old Quarter Horse filly. Approximately one week after arrival at the new barn she became anorectic, depressed, and had a fever of 104°F. Country Girl received penicillin and the trainer was instructed to hot pack the abscessed lymph node until it was ready to be lanced. A complete blood count (CBC) showed a mild leukocytosis and neutrophilia, which was the only abnormality detected. Country Girl was diagnosed with purpura hemorrhagica due to the history of a recent Streptococcus equi infection together with the clinical signs of immunecomplex disease and the absence of evidence for alternative causes.
