WA Livestock Disease Outlook - for vets

Livestock disease investigations protect our markets

Australia’s ability to sell livestock and livestock products depends on evidence from our surveillance systems that we are free of particular livestock diseases. The WA livestock disease outlook – for vets summarises recent significant disease investigations by Department of Primary Industries and Regional Development (DPIRD) vets and private vets that contribute to that surveillance evidence.

Recent livestock disease cases

Neurological signs and collapse in a six-year-old sheep at abattoir

• A Merino sheep was recumbent at ante-mortem inspection with neurological signs including blindness, abnormal eye movements and tremors. The animal was in very poor body condition and tachycardic and was euthanased humanely.
• Histopathology showed a severe, chronic, granulomatous enteritis and lymphadenitis, serous atrophy of fat and a suppurative bronchopneumonia.
• These findings were consistent with a diagnosis of ovine Johne’s disease (reportable), which was further supported by a positive faecal PCR test.
• As the sheep was over the age of 18 months and showing neurological signs consistent with the exotic disease scrapie, the submitting vet supplied appropriate brain and spinal cord samples for transmissible spongiform encephalopathy (TSE) exclusion testing. The test results  were negative, adding support to Australia’s freedom from this disease.
• Rebates for private vets and producers are available for suitable investigations that support the National TSE Surveillance Program. Read more on how vets and producers can access these rebates.

Tremors and deaths in five-week-old pigs

• Two pigs had died and 50 were affected with recent onset of tremors from a group of 200 pigs. Some pigs had also lost body condition.
• The submitting vet had made a provisional diagnosis of salt toxicity. On histopathology, there was an acute polioencephalomalacia with marked eosinophilic infiltrates. These lesions occur secondary to sudden electrolyte shifts in the brain, and are characteristic of salt toxicosis in pigs.
• All livestock can be affected by salt toxicity if fresh water is unavailable for more than 24 hours.
• Signs include excessive thirst, diarrhoea, neurological signs, rapid loss of condition, often progressing to coma and death.
• Affected pigs may move round in a circle using one foot as a pivot and may convulse. Convulsions can re-occur at approximately seven-minute intervals. 
• When water supplies have been interrupted, stock should be slowly re-introduced to fresh water in small, frequent amounts until rehydrated. Also consider using oral electrolytes in the drinking water.
• Read more on preventing salt toxicity in livestock and salt poisoning or water deprivation in pigs.
• Given the sudden deaths, testing for the exotic diseases African swine fever and classical swine fever was conducted, with negative results.
• Vets are reminded to remain on high alert for any signs of African swine fever as its spread across the world continues, most recently to Papua New Guinea.

High mortality rate and respiratory signs in broiler chickens

• A poultry producer noted a higher than normal mortality rate in 20-day-old chickens with some birds showing dyspnoea and gasping.
• Given these clinical signs are suspicious for the reportable diseases avian influenza and Newcastle disease, testing for these diseases was conducted as a priority, and was negative.
• Further examination showed extensive granulomatous pneumonia with fungal hyphae consistent with aspergillosis. A microbial culture confirmed the presence of Aspergillus fumigatus in the lungs of five birds.
• Aspergillosis can occur when spores in contaminated feed, litter or soil are inhaled by poultry. Typical signs include dyspnoea (often seen as gasping) and acute mortality rates of up to 50%, most often in younger birds. A chronic form can also develop, more often seen in older birds.
• In the commercial layer and broiler industries, use of risk-based vaccination in layers and breeders reduces the risk of exotic or Australian-origin virulent Newcastle disease virus by improving flock protection against the virus and displacing precursor viruses.
• A resource guide is available on the DPIRD website for veterinarians investigating poultry diseases.

In autumn, be on the lookout for:

Pig post-mortem guide available from DPIRD

DPIRD has produced a step-by-step guide to a pig post-mortem to assist vets, a resource that will be particularly useful if African swine fever is suspected. See our post-mortem resources webpage to download a PDF copy, or email waldo@dpird.wa.gov.au to request laminated copies for your practice.

Stepping up surveillance skills for animal disease threats across northern Australia

More than 30 vets from northern Western Australia, the Northern Territory and Queensland stepped up for a veterinary masterclass held in Broome in early March. The focus of the masterclass was to strengthen Australia’s preparedness to recognise and respond to disease outbreaks, particularly African swine fever. Photo credit: Pauline Brightling

More than 30 vets from northern Western Australia, the Northern Territory and Queensland stepped up for a veterinary masterclass held in Broome in early March. The focus of the masterclass was to strengthen Australia’s preparedness to recognise and respond to disease outbreaks, particularly African swine fever.

Our northern animal health surveillance systems are currently focused on the threat of African swine fever entering Australia, particularly as the virulent pig disease has now spread to our close neighbours Papua New Guinea, Timor-Leste and Indonesia.

Managing animal health surveillance across northern Australia is a herculean task that involves the collaboration and coordination of Commonwealth Government, Western Australian, Northern Territory and Queensland agencies and relies on the active involvement of private and government vets.

The Department of Primary Industries and Regional Development recently facilitated an animal health surveillance masterclass for northern Australian veterinarians to strengthen Australia’s preparedness to recognise and respond to disease outbreaks, particularly African swine fever.

The masterclass, held in Broome from 6-7 March, attracted more than 30 vets from northern Western Australia, the Northern Territory and Queensland, including each jurisdiction’s chief veterinary officer.

Recent international travel and border closures may have lessened some of the potential for the spread of African swine fever to Australia, but there is an ongoing threat from incoming mail containing illegally imported pork and illegally imported pork already present in the country that may contain the virus.

The masterclass took vets through the latest information on African swine fever and the sampling and post-mortem techniques needed to diagnose the disease. Participating vets were provided with a step-by-step guide to conducting a pig post-mortem and were also challenged by a hypothetical disease outbreak and asked how best to investigate and analyse it.

Participants in a masterclass for northern Australian vets held in Broome practised applying their investigative skills to a hypothetical disease outbreak. Pictured standing are DPIRD vet and co-organiser Andrew Larkins and WA Chief Veterinary Officer Michelle Rodan. Photo credit: Pauline Brightling

A range of other topics relating to disease investigation and surveillance were also covered in the masterclass.

Key presentations focused on current issues in the neighbouring Asia-Pacific region, investigating reproductive disease in northern Australia and the vital role that vets play in certifying that our stock are free from specific diseases.

It is this ability to demonstrate that we are free from priority diseases and can detect them quickly if they occur that underpins Australia’s reputation for excellent biosecurity and our access to global markets.  

Broome private vet Dave Morrell said the masterclass was a great opportunity to get vets from all over northern Australia in one place and to learn more about animal health surveillance in the region.

“Bringing northern vets together to engage with a common purpose and approach to the threat of disease introductions into northern Australia via this workshop has made a substantial contribution to the delivery of biosecurity and surveillance across northern Australia,” Dr Morrell said.

“The vets particularly benefited from the epidemiological session, which provided investigative and analytical approaches that many of us were not familiar with. These approaches will be vital in the event of a serious animal disease outbreak in northern Australia.”

Participants in a masterclass to increase preparedness for emergency animal diseases in northern Australia - Broome, March 2020. Photo credit: Pauline Brightling

The Northern Australia Biosecurity Surveillance (NABS) Framework was established by the Commonwealth Government in 2016 to ensure effective and sustainable surveillance systems for priority plant and animal diseases. The Masterclass was coordinated by DPIRD in Western Australia and funded by Commonwealth, State and Territory Governments.

More information about African swine fever is available at agric.wa.gov.au/asf. 

DPIRD disease investigation summary
October-December 2019

In the October-December 2019 quarter, DPIRD investigated 310 disease events in animals, primarily livestock. Submissions were received from both government and private vets, providing both support for WA’s claims of freedom from exotic diseases that could impact trade, and diagnostic information to aid producers in managing disease on their farms.

Reportable disease exclusions

During this quarter, there were 289 exclusions of reportable diseases across a number of species (see Figure 1). In some cases there were multiple reportable diseases excluded as part of the investigation. Johne’s disease in sheep and cattle and scrapie were the most frequently excluded (see Figure 2).

Endemic disease

Table 1: Commonly detected diseases in sheep during the Oct-Dec 2019 quarter by agricultural region

Table 2: Commonly detected diseases in cattle during the Oct-Dec 2019 quarter by agricultural region

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 particular livestock diseases. The WA livestock disease outlook – for vets summarises recent significant disease investigations by DPIRD vets and private vets that contribute to that surveillance evidence.

For more information, see:

• WA's animal health surveillance programs
• subsidies available to support disease investigations
• or contact your local DPIRD vet.

Feedback and subscriptions

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