A systematic approach to the neurological examination of llamas and alpacas

The clinical presentation of neurologic disorders in camelids varies widely depending on the underlying cause and localisation of the disease. Metabolic, cardiovascular and musculoskeletal conditions may also present with neurological signs and must thus be differentiated from those of true peripheral or central nervous system origin, through careful evaluation of history, clinical examination and diagnostic testing. Mentation and behaviour of camelids is generally evaluated from a distance, with subsequent assessment of cranial nerve function, gait, posture and postural reactions, spinal reflexes and muscle tone. Gait assessment often focuses on the differentiation between lower motor neuron weakness (LMN paresis) and general proprioceptive ataxia (with associated upper motor neuron weakness), in order to better localise spinal cord disorders. In this context, tail pull examinations may further aid in discerning upper versus lower motor neuron weakness. A thorough systematic neurological examination is thus paramount to achieve the following goals: determine the presence or absence of neurologic signs; localisation of the lesion (neuro-anatomic diagnosis); determine the etiology of a neurological condition.