We have seen foam on the eye and nose, but not quite like this. If the swan is stumbling and walking slowly, it may be indicative of something very wrong with this swan and the foam might be an abnormal coloration of the eye. This discoloration could be signaling some underlying problem such as poisoning, or if it was found on the beach, possibly drinking salt water instead of fresh water. Mute swans do not have a filtering organ to separate salt from the water and this could be a real problem for the swan. We would suggest that you capture the swan and get it to an avian veterinarian that is experienced in the care of swans, at least waterfowl. If there is no veterinarian available, try a waterfowl rehabilitator or wildlife rehabilitation center.

The swan should be thoroughly examined, blood drawn and tested for blood panels as well as any indication of bacterial, viral or fungal infection and then treated accordingly. If the bird has some kind of poisoning, then the sooner that charcoal is provided, an I.V., and other supportive care, the better the chances of survival.

On another note, this swan looks like a pen (female swan). Please let us know how this situation progresses. The Regal Swan