WA Livestock Disease Outlook - for producers

Recent livestock disease cases in WA

Annual ryegrass toxicity (ARGT) cause livestock deaths

• Reporting unusual deaths or disease in your stock to your private vet, a DPIRD field vet or the Emergency Animal Disease hotline on 1800 675 888 provides the best chance of diagnosing the problem correctly, so that it can be treated and prevented in the future. It also ensures that any reportable diseases are detected early, meaning there is more chance the disease can be eradicated quickly with less impact on our markets.
• In the past year, DPIRD has diagnosed 16 cases of annual ryegrass toxicity (ARGT) in livestock – seven in cattle, six in sheep, two in horses and one in goats. ARGT is caused by a toxin produced by bacteria that can infect annual ryegrass.
• In February, in a herd of 50 two-year-old Jersey cows, one died and one suddenly became uncoordinated, fell over and had muscle tremors. The herd was fed silage and was grazing mixed pasture.
• A private vet conducted an on-farm investigation and a post-mortem of one cow, and submitted samples to the DPIRD laboratory. The vet suspected the deaths were due to ARGT or a bacterial infection.
• Both the pasture and faecal samples tested positive for ARGT, confirming it as the cause of disease. 
• ARGT at this time of year is more likely to be from affected supplementary feed such as hay or silage. ARGT on pasture is most often seen in spring when livestock graze pastures containing infected ryegrass seed heads. Note that drying the grasses for hay does not eliminate the toxin.
• There is no specific treatment for ARGT, but less severely affected animals may recover with time when moved off contaminated pastures to a safe paddock.
• Preventing ARGT in livestock involves daily stock inspections, ryegrass testing, vendor declarations for bought-in hay, grain and chaff, good biosecurity to minimise introduction of the ARGT-causative organisms and paddock management.
• Subsidised testing may be available for animals that show neurological signs such as tremors in order to rule out reportable diseases such as transmissible spongiform encephalopathies (TSEs) – ask your vet for details.
• See DPIRD’s recent media release on ARGT, as well the DPIRD ARGT webpage for more information.

Bluetongue and screw-worm fly ruled out in sheep at abattoir

• DPIRD regularly receives samples from abattoirs, which are a key component of disease surveillance in Western Australia. The results from these cases contribute to proving WA’s and Australia’s freedom from certain diseases, which gives us a market advantage and allows us to export livestock products widely.
• Over the past month DPIRD has received two submissions to exclude reportable diseases from sheep at abattoir.
• In the first case, five Merino ewes from a line of 1044 had a nasal discharge, and reddened and cloudy eyes.
• Samples were tested for bluetongue virus, as it can cause nasal discharge in sheep. All samples tested negative. The results of this testing contribute to our proof of freedom from bluetongue in sheep in Australia.
• Testing at DPIRD showed that the animals had pink eye.
• In the second case, a Merino ewe with a maggot-infested wound was identified and removed from abattoir processing. The ewe was euthanased and maggots were submitted to DPIRD to exclude the exotic screw-worm fly (see Figure 1). The larvae were identified as the sheep blowfly, Lucilia cuprina. See the DPIRD flystrike tools webpage for more information.

Figure 1: Screw-worm fly maggots in a wound (Image: Department of Agriculture and Water Resources)

Respiratory disease in mixed age hens

• In a flock of 100 mixed-age birds, including turkeys, pheasants and chickens, eight died suddenly over a two-week period. Several birds had swollen eyes and eye discharge (see Figure 2).
• Two birds were submitted to the DPIRD laboratory for investigation. Testing showed they had the viral disease infectious laryngotracheitis (ILT), as well as chronic respiratory disease, caused by the bacteria Mycoplasma.
• Although treatment with antibiotics may reduce the signs of disease in the short term, birds become carriers of both of these infections, and disease is likely to reoccur in the future.
• Reportable diseases of poultry including avian influenza and Newcastle disease were ruled out as the cause of the disease.
• Biosecurity is key in preventing common poultry diseases from entering a flock, as well as protecting poultry from emergency diseases. See the DPIRD poultry biosecurity checklist for small landholders for biosecurity measures.

Figure 2: Chicken with ocular swelling and discharge

In early autumn, watch for these livestock diseases:

Odd behaviour or disease signs in cattle? Think Bucks for Brains!

We need your help to meet WA’s surveillance targets for bovine spongiform encephalopathy (BSE – mad cow disease) in cattle for the 2018/19 financial year. Australia does not have BSE but we need ongoing surveillance to maintain market access for our cattle and cattle products.

If you see any cattle with gait abnormalities such as wobbling, staggers or goose-stepping, constant trembling or increased sensitivity to sound and touch, contact your vet to see if you are eligible for a subsidised disease investigation. The owner receives a subsidy of $300 per animal for up to two animals. Veterinary, sample freight and laboratory costs are also normally covered. The DPIRD NTSESP webpage explains the program, conditions, criteria for eligibility and rebates or you can contact your local DPIRD vet.

WA Livestock Disease Outlook highlights benefits of surveillance

Australia’s ability to sell livestock and livestock products depends on evidence from our surveillance systems that we are free of livestock diseases that are reportable or affect trade. The WA livestock disease outlook – for producers summarises recent significant disease investigations by Department of Primary Industries and Regional Development vets and private vets. Data from these investigations provide evidence that WA is free from these diseases and supports our continuing access to markets.

We welcome feedback. To provide comments, email waldo@dpird.wa.gov.au. To subscribe, go to the webpage.