Why DAFWA collects livestock disease surveillance information
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 vets (WALDO) is collated from information collected by DAFWA and private veterinarians as part of proving Australia’s freedom from those diseases.
Recent significant cases submitted to the Animal Health Laboratories (AHL)
Mid-June to mid-July 2015
Lead poisoning in Friesian calves
- Cases of sudden death were investigated in three-month-old Friesian calves in the South-West.
- Six animals were found dead and one was collapsed and moribund.
- Clinical signs included blindness, lethargy, circling when assisted, anorexia and slobbering.
- An old battery which had been chewed was found in the paddock with the calves. Batteries contain lead.
- A post-mortem showed an empty gastrointestinal tract except for pus-like content in the duodenum. A full sample set was taken and sent to AHL.
- Histopathology revealed congestion and haemorrhage in the heart muscle, congestion and oedema in the lungs and congestion in the medulla of the kidneys.
- Blood taken for biochemistry showed elevated blood lead levels consistent with a diagnosis of lead toxicosis. No other significant changes were noted.
Under the Biosecurity and Animal Management Act 2007, livestock known or suspected to have lead residues are quarantined to prevent harmful residues entering the human food supply. Veterinarians can assist clients by advising them to ensure livestock do not have access to lead sources such as batteries, machinery and painted sheds and to securely fence farm dumps.
Read more on preventing lead poisoning in livestock.
Brucella abortus ruled out in three separate cases of abortion
Case 1 – Angus heifers in South-West
- A case of aborted and stillborn calves in an Angus herd in the South-West was investigated.
- Five two to three-year-old heifers had stillborn calves, and four aborted out of a herd of 16 animals. Seven gave birth to live calves.
- Blood samples were taken from the 16 animals to test for causes of stillbirth and abortion. Exclusion testing for Brucella abortus returned negative results in all animals.
- Testing for Leptospira and Campylobacter organisms was also negative, but two animals had positive ELISA tests for Neospora antibodies. Low selenium levels were seen in all animals except one.
- Serological testing showed bovine pestivirus (mucosal disease/bovine viral diarrhoea complex) was also circulating in this unvaccinated herd.
Case 2 – Angus cows in the Great Southern
- Four cows in a mob of 50 Angus cows had stillborn calves in the Great Southern.
- The mob had access to good pasture, water and supplements.
- One stillborn calf was post-mortemed. Samples taken for histopathology did not reveal any specific lesions.
- Bacterial culture did not reveal any significant organisms and selective culture for Campylobacter spp. was negative. Leptospira were not seen in urine examination.
- Blood samples were taken from the affected cows to rule out Brucella abortus, Neospora and Leptospira spp. All tests results were negative.
- One of the cows had a slightly lower than normal blood selenium level.
- No definitive cause of the stillbirth was established.
Case 3 – Friesian heifer in the South-West
- A two-year-old Friesian heifer aborted in the South-West.
- At the time of examination she had retained foetal membranes and a fever.
- Blood samples from the heifer, foetal membranes and fresh and fixed tissues from the aborted calf were submitted to AHL for investigation.
- Histopathology revealed necrotising enteritis, fibrinosuppurative placentitis and meningitis, all with bacilli present in the fields.
- Brucella abortus testing was negative, which supports Australia’s disease-free status, and pestivirus and Neospora tests were also negative.
- Theileria orientalis PCR was positive with Theileria orientalis var. ikeda detected. This is the second diagnosis of Theileria orientalis in the South West. Read more on BATOG.
- Bacterial culture of the lungs, liver and stomach contents of the foetus returned a pure growth of Listeria monocytogenes. The histological changes noted were typical of a Listeria infection in a near-term foetus.
- This case shows the importance of submitting the aborted foetus and / or placenta if possible, to improve the chances of a definitive diagnosis.