State-owned agricultural agency AssureQuality is warning farmers to watch for facial eczema on stock after recording extremely high spore counts across New Zealand.
Facial eczema is caused by a pasture fungus, which produces a toxin that poisons animal livers. It also triggers skin damage similar to severe sunburn.
With highhumidity and tropical rain forecast, spore counts were expected to increase, said AssureQuality's communications manager Lisa Williams.
Veterinary pathologists have also found outbreaks of the condition in already treated herds - caused possibly by under-dosing of zinc oxide or late treatment, Ms Williams said.
Common prevention techniques include giving zinc oxide by regular oral drenching, zinc sulphate via the water supply, long-acting medication inserted in a stomach of the animal, and spraying pasture with fungicide.
Infected animals were sensitive to light and looked distressed - often with reddening and swelling of skin around the eyes, ears, lips, nose and udder - as well as seeking shade and showing restlessness.
Facial eczema affects sheep, cattle, goats and deer.
In the top half of the North Island high spore counts have been recorded in Maungaturoto, Whakatane, Matamata, Raglan, Hamilton, Waipa, Otorohanga and Waitomo.
