LOCAL farmers are encouraged to monitor sheep nearing their last month of lambing closely with dry conditions leading to calcium deficiencies and birthing difficulties in some ewes.

Rural Lands Protection Board veterinarian Christine Haylock said that while the condition was common, she has not seen an example of it in a flock situation on the Monaro yet.

"If there's no grass in the ewes’ diets and they are being fed grain, then farmers need to put calcium supplements out to increase the calcium levels in their diets," she said.

Dr Haylock said that even in an ideal season sheep were still susceptible to calcium deficiencies, which can lead to problems during the advanced stages of lambing, loss of the lamb and the ewe.

"A lack of calcium affects the way their muscles work, you'll often find them sitting down in the paddock and they find it difficult to walk," Dr Haylock said.

"If a ewe is in good enough shape they can recover, but the sheep this year are really weak, some haven't had a decent feed in months," she said.

"An injectable form of calcium given to affected sheep should see their condition improve within a couple of hours, if the problem is calcium."

Dr Haylock said the condition was often confused with pregnancy toxemia, which had similar symptoms.

Pregnancy toxemia occurs in ewes that are not getting enough nutrition during the last stages of pregnancy.

Dr Haylock said ewes suffering pregnancy toxemia usually do not recover, and are unable to deliver a healthy lamb.

"Pregnancy toxemia is a risk every year, but is probably worse this year because of the lack of feed," she said.

"This year is such a tough year and there's probably more twins this year because the conditions were a little better when the ewes fell pregnant."

Dr Haylock said that twin lambs drain more glucose and energy from the ewe, which is why they need to eat more during the later stages of pregnancy.

"Not very many will recover from pregnancy toxaemia, it's much harder to nurse," she said.

"The symptoms are very similar, you'll often find them down and weak,"

"They're out there for the crows then."