Safety of ribavirin in cockatiels (Nymphicus hollandicus) – a preliminary study

Viral infections remain a major health concern in psittacine birds, with avian bornaviruses (ABV) causing proventricular dilatation disease (PDD), a chronic and often fatal condition. Ribavirin, a broad-spectrum antiviral drug widely used in human medicine, has shown in vitro (ABV) and in ovo (Newcastle disease virus) efficacy against some avian viruses, but its safety profile in birds is largely unknown. This study aimed to evaluate the safety of prolonged ribavirin administration in healthy cockatiels (Nymphicus hollandicus) aged approximately 6 months. The experiment consisted of experimental group (10 cockatiels) and negative control group (10 cockatiels). Ribavirin was administered to the experimental cockatiels according to the following protocol: orally (by gavage at dose 30 mg/kg body weight [BW]/day) two consecutive 28-day courses (course 1 & 2) separated and followed by 14-day recovery periods, then 15 mg/kg BW/day orally and 15 mg/kg BW/day intranasally for 28 days (course 3). The cockatiels were regularly weighed, clinically examined, and blood was collected for hematological and biochemical analyses. No clinical signs of adverse reactions were observed, neither during the therapy nor for 12 weeks after the therapy. BW changed significantly during the experiment, however without any link to ribavirin treatment. Only hematocrit decreased significantly after the ribavirin course 1. Our results indicate that ribavirin at 30 mg/kg BW, administered orally or in combination with intranasal dosing does not appear to cause apparent clinical or laboratory adverse reactions in cockatiels, except for potential alteration of hematocrit which is, however, too mild to be clinically meaningful. This provides an essential first step toward evaluating ribavirin as a therapeutic option for avian viral diseases.