Sheep producers are being warned to keep an eye out for iodine deficient lambs as large amounts of rainfall strip iodine out of soils.
Victorian district veterinary officer Dr Jeff Cave said goitre, which was caused by iodine deficiency, led to enlarged thyroid glands seen as swellings in the neck of affected lambs, which were born weak and die easily from the cold.
"Particularly after a wet season I hear farmers comment 'some of my newborn lambs have an enormous lump under its throat'," Dr Cave said.
"Invariably this is relating to goitre.
"If you consider the main source of iodine is from sea salt, which is leached from soils during heavy rainfall, it is not surprising that many soils in Victoria are deficient in iodine."
He said cases of goitre typically occured after three consecutive months of 80 millimetres or more of rain.
"Since a reasonably wet winter has been forecast following our effective autumn break, producers with flocks lambing from mid-winter onwards this year should be considering the prevention of goitre in their flocks," he said.
"Like other essential trace minerals, iodine is only required in small amounts."
He said the thyroid gland produced hormones, which were essential for life.
"A lamb or kid with goitre will often be undersized or stillborn, have a reduced wool cover, and be weak and susceptible to cold stress," he said.
"Property owners who have never seen goitre will often see it following a shift in their enterprise from producing cattle to sheep or goats."
Dr Cave said an outbreak of goitre can be challenging to manage since any affected lambs or kids would have a low survival rate and the deficiency in the ewes or does needed to be corrected quickly before lambing or kidding occurs.
"Iodine deficiency is easy to prevent, by providing iodised salt from the third month of the ewes' pregnancy," he said.
"This can be given in a variety of ways such as iodised salt blocks or potassium iodide drenches."
He said speak to your local veterinarian if you needed further advice.
The story Iodine deficiency can lead to low survival of lambs first appeared on Farm Online.