Rhododendron poisoning in alpacas (Vicugna pacos) in Northern Germany

Abstract

Poisoning is often suspected to be the origin of disease in South American camelids (SACs) by owners, but only in a few cases this assumption can be confirmed. In small ruminants, rhododendron poisoning is a common emergency for livestock veterinarians. However, this condition has rarely been reported in SACs so far. This paper provides information regarding clinical findings, hematology, clinical chemistry, and treatment of four alpacas after presumed intake of rhododendron leaves including pathological findings of one of the animals. Rhododendron leaves contain grayanatoxins that lead to hyperpolarization of excitable cells. Clinical signs that were observed in the presented alpacas comprised: salivation, dehydration, decreased motility of compartment 1, uncoordinated regurgitation, and cardiac arrhythmia. Clinical chemistry revealed that rhododendron poisoning was associated with metabolic acidosis and azotaemia, hyponatremia and hyperkalemia. Most striking macroscopic and histopathological findings included gastric ulceration, and renal infarcts along with inflammatory changes. Leaves of Rhododendron spp. were identified in the forestomach content of this animal. Affected animals were treated symptomatically as there is no specific antidote in rhododendron poisoning. This included parenteral rehydration, treatment of metabolic acidosis (infusion of sodium bicarbonate solution), and oral administration of activated charcoal to bind potential toxins. In addition, antibiotic treatment might be necessary to prevent aspiration pneumonia in case of uncoordinated regurgitation. Of the four animals, the worst affected alpaca was euthanized, one had minimal signs and two responded to supportive care and recovered. In conclusion, rhododendron poisoning might be fatal for alpacas in individual cases and therefore rhododendron bushes should not be placed in the habitat of SACs.