ovis biovar affects small ruminants. Their ability to reduce nitrate can be used to distinguish between the subtypes. The equi biovar can reduce nitrate, while the ovis biovar generally cannot, but some exceptions have been demonstrated. Coryneform bacteria, including C. pseudotuberculosis, can also be differentiated using a biochemical test called the API Coryne system, which involves enzyme and carbohydrate fermentation tests and requires 24–48 hours to perform. Finally, genetic sequence analysis can be used to confirm the identification of C. pseudotuberculosis if biochemical identification is not sufficient. In fact, a multiplex polymerase chain reaction assay has been developed using a number of characteristic genes that can differentiate between the closely related species of corynebacteria – C. pseudotuberculosis, C. ulcerans, and C. diphtheriae. Clinical signs Disease in small ruminants C. pseudotuberculosis causes a disease known as caseous lymphadenitis that most commonly affects small ruminants, such as goats and sheep. Caseous lymphadenitis often presents with pyogranulomatous abscess formation. Abscessation can occur in numerous areas, but it most commonly affects the cutaneous region and superficial lymph nodes. This is known as the external form of the disease and is the primary form affecting goats. Nodular lesions are often visible. The internal form of the disease is more of a concern for sheep. In this form, internal organs and lymph nodes are affected. Over time, these abscesses deposit multiple layers of fibrous capsules which gives them a lamellated appearance upon cross section. The contents of the abscess are thick and purulent, and the abscess often ruptures. This can be an important source of contamination to other animals in the herd. The internal manifestation of the disease is harder to recognize, as the clinical signs are not as obvious; however, they may include a reduction in reproductive ability and diminished body condition. Depending on the location of the lesions and the pressure they exert on their surroundings, the animal may develop dysphagia and abnormal rumination. Disease in cattle The most common clinical sign for infected cattle is ulcerative lesions of the skin. Mastitis, an infection of the udder that is most commonly caused by species of the Streptococcus and Staphylococcus genera, may also be caused by C. pseudotuberculosis in rare circumstances. Infected cattle may also have a higher frequency of abortions. Disease in horses C. pseudotuberculosis can also cause disease in horses, which also present with abscessation, but the lesions are most commonly seen on