WA Livestock Disease Outlook - for producers

Reporting livestock disease protects our ability to trade

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. To gather this proof of freedom, the Department of Agriculture and Food, Western Australia (DAFWA) investigates cases where livestock show signs of disease similar to reportable or trade diseases.

The WA livestock disease outlook – for producers is collated from information collected by DAFWA and private veterinarians as part of proving Australia’s freedom from those diseases. In 2015/16, data from our surveillance systems allowed WA to access markets valued at $2 billion.

Recent significant cases submitted to DAFWA Diagnostic Laboratory Services (DDLS)

Case data from March to April 2017

Rift Valley fever testing in sheep supports export markets

• 15 Merino weaners died in a flock of 300 in the Great Southern.
• The animals showed progressive blindness and wasting leading to death.
• Following a postmortem, the vet considered hypovitaminosis A, polioencephalomalacia or lupinosis to be possible causes.
• Laboratory testing did not identify the cause of death, but low vitamin A levels in two sheep suggested that there could be a general deficiency among the flock. It was also recommended that paddocks be examined for Stypandra sp. or bracken ferns, which may cause blindness.
• Given the high mortality in young sheep, Rift Valley fever (RVF) was also tested for with negative results, supporting Australia’s claim of freedom from RVF.
• RVF is an insect-borne virus that affects primarily cattle, sheep and goats, but humans and camels are also hosts. It has never occurred in Australia but could enter the country via infected people, livestock or insects. RVF causes high death rates in young animals, fever, abortions and bloody diarrhoea.
• Reporting suspicious disease signs to your local DAFWA vet or private vet or the emergency animal disease hotline on 1800 675 888 helps to prove to trading partners that we are looking for these diseases and testing for them.

Neurological signs in a young steer

• A one-year-old Murray Grey steer was weak and uncoordinated and was subsequently humanely euthanased.
• A postmortem found a blood clot in the spinal cord, which may have caused the neurological signs. Other findings included an inflamed intestinal tract and a parasite infection.
• Other conditions ruled out by laboratory testing included annual ryegrass toxicity (ARGT), lead toxicity, polioencephalomalacia and calcium and magnesium disorders.
• Calling a vet and obtaining laboratory testing allowed the producer to identify herd health issues and manage them to reduce their impacts.
• An inflamed rumen can occur from excessive grain and parasites may be exacerbated by wet weather and high stocking densities.

Foot-and-mouth disease (FMD) excluded in a dairy cow in the South West region

• A four-year-old dairy cow was found lying down with a lesion in the mouth. The cow had been ill-thrifty for three weeks since calving, had reduced gut activity, dry faeces and low body condition.
• Given the presence of a mouth lesion, samples were taken to rule out FMD and vesicular stomatitis.
• Apart from the mouth lesion, there were no other FMD signs such as sores around the feet or the udder and there was no history of recent travel or new introductions of stock.
• Testing for FMD and vesicular stomatitis at DDLS and the Australian Animal Health Laboratory (AAHL) was negative.
• Samples taken from the cow at postmortem showed the likely cause of disease was a bacterial uterus infection following calving. Mouth lesions were presumed to be due to trauma or burn.
• Foot-and-mouth disease is an exotic, highly infectious viral disease that affects cloven-hoofed animals. Blisters may form in the mouth, nostrils, teats or between the toes. Vesicular stomatitis is another disease of cattle, pigs and horses that can cause blisters in the mouth and on teats and feet.
• The producer who reported this case to a vet helped to provide evidence that Australia remains free of FMD and vesicular stomatitis, which supports our ability to export livestock products.

In late autumn/early winter, be on the lookout for:

Disease	Typical history and signs
Scour worms in sheep	Sheep may be carrying higher worm burdens due to early rainfall. Scouring usually occurs once green feed is established. High worm burdens in autumn are likely to result in significant worm problems in lambs during the spring. Worm egg counts (WEC) performed in autumn can help to assess if drenching is required. Read more on sheep worm control.
Grass tetany in cattle	Susceptible cattle are generally older, highly productive cows in their first four months of lactation grazing grass pastures. Extreme weather events may precipitate cases. Signs may include twitching, convulsions, excitement, apparent aggression, stiff gait and sudden death. Magnesium-deficient cattle normally have disease signs similar to transmissible spongiform encephalopathy (TSE) and may be eligible for the TSE exclusion subsidy. Contact your vet for details. A variety of factors will affect the magnesium content of grasses and some properties may experience cases of grass tetany repeatedly.  Read more on grass tetany in beef cattle.
Photosensitisation	Photosensitisation can result from consuming plants containing photosensitising compounds or from liver damage due to other disease. It is often first seen in autumn after green feed germinates. Signs include jaundice (yellow gums, eyes), weakness, depression, severe irritation and/or swelling of face and ears and lameness. It is important to call a vet for diseases that look like photosensitisation as these include exotic diseases like bluetongue virus and FMD. Testing for these diseases supports our ability to trade. Read more about photosensitisation in livestock.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Increased risk of pregnancy toxaemia in ewes

Due to the higher feed availability during joining, it is expected that higher numbers of twin pregnancies will be seen this season, which will increase the energy demand on the ewe and heighten the risk of pregnancy toxaemia as ewes approach lambing. Discuss the appropriate feeding program for pregnant ewes with your sheep consultant or adviser. Read more about pregnancy toxaemia.

Previous issues

Previous issues of WALDO - for vets and WALDO - for producers are available on the DAFWA website on the newsletter archive page or by searching 'WA livestock disease outlook'.

Feedback

We welcome feedback. To provide comments or to subscribe to the monthly email newsletter, WA livestock disease outlook, email waldo@agric.wa.gov.au.