Multimodal analgesia in a Southern White Rhinoceros (Ceratotherium simum) with pentosan polysulfate, gabapentin, amantadine and phenylbutazone to manage chronic pain

Abstract

A 38-year-old white rhinoceros bull (Ceratotherium simum) was treated with phenylbutazone over a period of four years for chronic osteoarthritic and neuropathic pain of the thoracic limbs. Initially the lameness was sporadic and responded well to phenylbutazone (4 mg/kg PO SID). The lameness increased in severity during the winter months. Four years after treatment was initiated, there was an increase in the severity and incidence of the lameness. Analgesia was augmented by the addition of non-conventional analgesic drugs. Pentosan polysulfate was administered IM at 3 mg/kg once a week for two treatments and thereafter monthly when possible. Gabapentin was used at 8 mg/kg but produced ataxia and anorexia. The dose was reduced to 4-5 mg/kg PO SID. Amantadine (3 mg/kg PO BID) was added to the multimodal analgesia and produced a significant improvement in the clinical lameness. Chronic inflammation was monitored using both automated and manual fibrinogen methods. Eventually the rhinoceros was euthanized on humane grounds when treatment was unable to produce suitable clinical relief.