SHEEP farmers may be enjoying a good season, but they are being warned it could lead to a fatal lamb disease.
Goitre, more common in wet years, is caused by an iodine deficiency in pregnant ewes which can be fatal in lambs.
Robert Suter, of the Department of Primary Industries, said the deficiency affects lambs production of thyroid hormones which controls metabolism.
"The thyroid keeps the animal metabolically active, and for young lambs that's heat," said Mr Suter.
"Without iodine they are susceptible to hypothermia and dying of the cold."
Mr Suter saw an increase of goitre in last year's lamb and kid mortality surveillance project, which he co-ordinated.
He said the disease was more likely in an above average rainfall year as pasture growth was more rapid and iodine levels became diluted.
Mr Suter said the disease was preventable by treating ewes in pregnancy with either a one-off treatment, such as potassium iodine drench, or an iodised salt lick.
Merino stud breeder Doug Pemberton of Nicolson, in East Gippsland, said he would take preventative measures.
Mr Pemberton said he preferred to drench his ewes and didn't think the stock licks gave pregnant ewes enough iodine.
The DPI's lamb and kid mortality survey is in its third year and Mr Suter said the project looked for exotic diseases and provided an audit.
Mr Suter said any farmers with lambs that have dies up to weaning can take part and will get an analysis of the cause death.
