Spike in Phalaris poisoning outbreaks on the Central Tablelands
12 November 2015
A spike in cases of phalaris poisoning has been reported on the Central Tablelands with one farmer losing up to 30% of young ewes in a mob.
Central Tablelands Local Land Services Regional Veterinarian, Bruce Watts, says this unusual increase in reports of phalaris poisoning is a reminder to farmers to be on alert, particularly when bringing new sheep on to a property.
"It's not unusual to occasionally lose one or two sheep due to phalaris staggers, however in recent months Local Land Services vets have investigated half a dozen cases between Bathurst and Orange involving significant numbers," said Bruce.
Phalaris is a highly productive pasture species, however particularly during rapid growth the plant produces alkaloids which can damage the nervous system.
Research has found a correlation between low soil cobalt levels and outbreaks of phalaris staggers. Legumes contain significantly higher levels of cobalt than Phalaris and the risk of staggers diminishes with a greater proportion of legumes in the pasture.
Characteristic signs of toxicity are head nodding and bunny hopping with a wide based gait.
According to research published on the Flock & Herd website, most cases occur after one to two months of grazing. Signs can arise up to two months after stock are moved off Phalaris and usually persist for life.
Animals most at risk are young sheep that have been recently brought on to the property.
Phalaris poisoning can cause sudden death from either heart failure or brain disease within 48 hours of exposure to Phalaris pastures. Phalaris can also cause damage to the brain and spinal cord.
"Initially this is reversible if exposure is limited, but sheep can also develop a chronic, irreversible form of Phalaris staggers. This syndrome, which is characterised by tremors and an unsteady, uncoordinated gait, is of most concern to livestock producers," said Bruce.
"Phalaris staggers takes longer to develop and results in a neurological disorder characterised by an unsteady stumbling gait."
"Outbreaks of Phalaris poisoning tend to be sporadic and very difficult to predict," explained Bruce.
"Exposure can result in permanent brain and nervous system damage, and losses can continue for up to 5 to 6 months after initial exposure."
"Unfortunately there is no cure, although the application of cobalt bullets before sheep are moved onto Phalaris pastures can prevent the development of Phalaris staggers for at least two years."
"Recent rain may prompt a fresh flush of Phalaris growth, increasing the potential for further toxic outbreaks."
"If pastures contain a lot of phalaris, it may make economic sense to use cobalt bullets as a preventative treatment, particularly in young sheep that are new to the property."
"We have also seen some potential cases of Phalaris toxicity in cattle. While cows are less susceptible to the problem, cases can occur where stock lose weight due to the effects of the toxin on the brain."
For more information about Phalaris related toxicity contact Bruce Watt on 02 6333 2300 or 0428 935 559, or alternatively log on to www.flockandherd.net.au
Media contact: Kylie Krause on 0439 608 370