Progressive Lameness of a Greater One-Horned Rhinoceros (Rhinoceros unicornis) Associated with a Retroperitoneal Abscess and Thrombus Caused by Streptococcus dysgalactiae Subspecies equisimilis.

In rhinoceroses, lameness is an occasionally seen symptom primarily caused by lesions affecting the feet and interdigital space. A 3-year-old male Greater one-horned rhinoceros developed a progressive, severe movement disorder of the right hind limb with subsequent death. The pathological analysis diagnosed a severe, retroperitoneal abscess and chronic thrombosis of the right iliac artery. Streptococci detected in the abscess were further identified as Streptococcus dysgalactiae subspecies equisimilis by culture and molecular techniques. The identical isolate was also identified in a vaginal swab of the dam. The list of differential diagnoses for lameness in rhinoceroses must be expanded by processes affecting other than the extremities per se.