Why DAFWA carries out surveillance for livestock disease
Australia’s access to markets for livestock and livestock products depends on evidence from our surveillance systems that we are free of reportable and trade-sensitive livestock diseases. To gather this proof of freedom, the Department of Agriculture and Food, Western Australia (DAFWA) investigates cases where livestock show signs similar to reportable or trade-sensitive diseases. The WA livestock disease outlook – for producers (WALDO) is collated from information collected by DAFWA as part of proving Australia’s freedom from those diseases.
Recent significant cases submitted to the Animal Health Laboratories (AHL)
Case data from early February to mid-March 2015
Respiratory signs and sudden death in lambs
- Respiratory signs and sudden death were seen in six-month-old lambs in the Great Southern.
- In total, 20 lambs died from a mob of 2000.
- The sheep had been fed ad lib for 60 days and were adequately vaccinated for pulpy kidney.
- A post-mortem on one animal showed a severe, chronic pneumonia.
- As some of the disease signs were similar to the exotic disease, Maedi visna virus or ovine progressive pneumonia, fresh lung tissue was sent to the Australian Animal Health Laboratory (AAHL) in Geelong to rule out this disease. Testing was negative.
- Further testing confirmed a diagnosis of Mycoplasma ovipneumoniae pneumonia with secondary Mannheimia haemolytica infection, which is a common secondary bacterial infection in young animals.
- Secondary bacterial pneumonias are often preceded by viral infections, environmental stress and depressed immune systems.
Weakness and deaths in Merino weaners
- Weakness, collapse and deaths in one-year-old Merino weaners were investigated in the Great Southern.
- In a flock of 1400, eight were found dead and 100 displayed signs of weakness.
- The sheep had a body condition score of 2.5 and had been grazing oat stubbles with lupin grain supplementation since January.
- A post-mortem on one sheep showed no significant visible lesions on the organs. The gastrointestinal tract showed widespread chronic inflammation, which was attributed to intestinal worms.
- Tissue testing of the liver provided a diagnosis of vitamin E and selenium deficiency.
- Further blood sampling from other sheep in the mob may assist in assessing the vitamin E and selenium status of the flock.
- Any unexplained sudden deaths should be investigated by a vet to rule out exotic or reportable diseases.
- Read more on vitamin E and selenium deficiency.
Sudden death in two-year-old cows
- Cases of sudden death were investigated in two-year-old cows in the Great Southern.
- Five cows died over a two-day period from a herd of 280 animals.
- The herd was branded, drenched and received micro-mineral supplements one week before the deaths.
- Seasonal conditions were dry and the cows were moved to a new paddock 4–5 days before the deaths.
- Post-mortems on two cows did not show any visible disease.
- Blood tests showed calcium, magnesium and phosphorus levels within normal ranges, with no liver or kidney damage. Laboratory testing revealed heart muscle damage, fatty liver and fluid build-up on the lungs, suggestive of cardiac glycoside or 1080 poisoning.
- No poisonous plants were seen in the current paddock but laneways/transit paddocks are being checked.
Suspected oesophageal weakness or possible plant toxicity in mixed age Merinos
- Similar clinical signs and deaths have been occurring in sheep on a South West Coast farm annually.
- Cases begin with swelling of the abdomen and a hunched appearance which progress over 2–3 weeks to staining around the mouth, animals lying down and dying.
- The sheep all graze arum lily, which appears to precede the swelling of the abdomen.
- Previous cases have led to the suspicion of muscular weakness of the oesophagus with subsequent reflux and inhalation into the lungs, leading to severe pneumonia.
- Producers who see similar signs should contact their local veterinarian or DAFWA field veterinarian.
In late autumn, be on the lookout for:
Pregnancy toxaemia or ketosis
- This condition is usually seen in late-pregnant ewes, particularly those carrying multiple lambs.
- The affected ewe often separates from the mob and is off food, drowsy or comatose.
- Tremors and blindness often precede death by 3–4 days.
- Read more on pregnancy toxaemia.
Hypocalcaemia in ewes
- Generally ewes in the last six weeks of pregnancy and the first month of lactation are most at risk.
- There is a rapid onset of muscle trembling and weakness with the affected ewes sitting on their brisket, alert but unable to get up.
- Death often occurs within 24 hours.
- Weather changes or periods of stress that reduce food intake can trigger this condition.
- Read more on hypocalcaemia.
Calf scours
- Calf scours often affects young calves in late autumn and early winter.
- Signs include depressed appearance, diarrhoea, dehydration, collapse and death.
- Read more on calf scours.
Crownbeard toxicity in sheep
- Grazing the summer weed crownbeard leads to a loss of appetite, lethargy, heavy breathing, frothing from the mouth and nostrils and sudden death.
- Read more on crownbeard toxicity.
Royalties for Regions surveillance information: new pilot program to boost disease surveillance
The R4R Subsidised Disease Investigation Pilot Program is about to be launched to boost surveillance and testing for emergency animal diseases in WA. The program, funded by Royalties for Regions, will subsidise the cost to engage a veterinarian to investigate signs of disease in your stock (cattle, sheep, pigs or goats).
The pilot aims to encourage producers to contact a veterinarian to conduct a thorough disease investigation, helping to ensure emergency animal diseases are detected early. Information from such investigations provides evidence that Australia is free from many trade-sensitive diseases, which supports market access. Producers also benefit by determining the cause of disease, enabling them to put control programs in place and boost their productivity and profitability.
More information is available on the Subsidised Disease Investigation Pilot Program webpage or from the program co-ordinator Kevin Hepworth by email kevin.hepworth@agric.wa.gov.au or mobile 0475 834 486.
Previous issues
Previous issues of WALDO - for producers are available on the DAFWA website on the newsletter archive page.
Feedback
To provide feedback, email Dr Bruce Twentyman on bruce.twentyman@agric.wa.gov.au