Department veterinary officer Marion Seymour said there were a number of reasons heavy rainfall over the past few months could lead to decreased production and even livestock losses.

Producers experiencing stock losses should contact the Department or a private veterinarian to enable an early diagnosis and appropriate management to prevent further losses.

Dr Seymour said summer rain could reduce the nutritional value of annual pastures and crop stubbles causing stock to graze other sources of feed including poisonous plants.

“The department has investigated several cases of stock losses associated with lesser loosestrife (Lythrum hyssopifolia), a widely distributed weed in WA,” Dr Seymour said.

“The wetter seasonal conditions have favoured its growth and it is currently growing rapidly and flowering in many pasture and stubble paddocks in the lower South West.”

Lesser loosestrife has previously been recorded as causing significant mortalities in sheep, especially where it represented the only available green feed in stubble paddocks. It is an upright, hard stemmed plant similar to rosemary that grows to 40 cm in height and has tiny pink flowers.

“Stock grazing lesser loosestrife suffer from both liver and kidney damage, thought to be due to toxic tannins,” Dr Seymour said.

“Affected stock should be removed from the paddock containing the weed and fed good quality hay or a low protein diet and monitored closely.

“Stock must also have a fresh supply of water to assist their reduced kidney function, and access to shade as animals with damaged livers are at risk of photosensitisation.”

If producers suspect they have an unusual disease in their stock and cannot contact their usual veterinarian they can call the Department of Agriculture and Food’s Animal Health Laboratories on 9368 3351 (office hours) or the Emergency Animal Disease hotline on 1800 675 888 (after hours).