Neurological Causes of Diaphragmatic Paralysis in 11 Alpacas (Vicugna pacos)

Byers, S.; Barrington, G.; Nelson, D.; Haldorson, G.; Holt, T.; Callan, R.

Background: Diaphragmatic paralysis is a relatively uncommon medical condition in animals not reported in alpacas. Objectives: Describe the signalment, physical examination, diagnostic testing, clinical, and histopathologic findings related to diaphragmatic paralysis in alpacas. Animals: Eleven alpacas with spontaneous diaphragmatic paralysis. Methods: A retrospective study examined medical records from a 10‐year period and identified 11 alpacas with confirmed diaphragmatic paralysis admitted to Washington State University and Colorado State University Veterinary Teaching Hospitals between September 2003 and October 2009. Results: The 11 alpacas ranged in age from 2 to 12 months. Fluoroscopic imaging confirmed the presence of bilateral diaphragmatic paralysis in the 7 alpacas that were imaged. Arterial blood gas analyses showed hypercapnea, hypoxemia, and low oxygen saturation. Seven alpacas died or were euthanized between 2 and 60 days after onset of respiratory signs. Histopathologic examination of tissues found phrenic nerve degeneration in the 6 alpacas that were necropsied and additional long nerves examined demonstrated degeneration in 2 of these animals. Two animals had spinal cord lesions and 2 had diaphragm muscle abnormalities. No etiologic agent was identified in the alpacas. Conclusions and Clinical Importance: The etiology for diaphragmatic paralysis in these alpacas is unknown. A variety of medical treatments did not appear to alter the outcome.