My cockatiel has white stuff growing that comes back after I wipe it. What should I do?

Hello. The picture isn’t clear, so I can’t judge the exact situation. If the white stuff looks like pus, the eye may be infected and inflamed; rinse it with saline or eye wash, then apply pet antibiotic eye drops, or if none, erythromycin or aureomycin (chlortetracycline) eye ointment.

Meanwhile, keep the environment clean and disinfect the cage regularly to reduce bacteria, fungi, and mites. If you have other parrots, isolate the sick one for treatment.