WA Livestock Disease Outlook - for vets

Supporting Australia's ability to sell livestock and livestock products

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 which 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 vets (WALDO) is collated from information collected by DAFWA and private veterinarians as part of proving Australia’s freedom from those diseases and in 2014/15 allowed WA to access export markets valued at $1.6 billion.

Recent significant cases submitted to the Animal Health Laboratories (AHL)

Case data from mid-December 2015 to mid-February 2016

African and classical swine fever exclusion in pigs

  • Illthrift and mortalities were investigated in 10 to 11-week-old piglets over the past four months.
  • In a batch of 800, 50 have died and eight were sick at the time of the investigation.
  • Piglets go off food, become thin, jaundiced and develop respiratory distress. The deterioration is rapid and death follows quickly.
  • Post-mortems were carried out and fresh and fixed tissues were submitted to the laboratory for examination.
  • Histology revealed a systemic vasculitis and changes in the lung tissue consistent with pneumonia.
  • Acute haemorrhages and oedema of the cerebral meninges and parenchyma were caused by a necrotising vasculitis. The differential diagnosis list for acute vasculitis includes classical swine fever (CSF), African swine fever (ASF), porcine respiratory and reproductive syndrome (PRRSV) and porcine circovirus (PCV).
  • PCR at the Australian Animal Health Laboratory (AAHL) confirmed a diagnosis of porcine circovirus 2 associated disease (PCVAD). The AAHL excluded the exotic diseases ASF, CSF, PRRSV.
  • PCV affects lymphatic tissues and increases the incidence and severity of other endemic diseases.
  • Read more on ASF and CSF. Read more on PCVAD.

Malignant catarrhal fever (MCF) in cattle

  • One 12 to 18-month-old Brahman bull, from a herd of 20, died after being listless and not eating for a few days in the Mid-West.
  • The animal had been vaccinated for clostridial diseases (7 in 1) and vibriosis six weeks prior to the illness. An anthelmintic pour-on was applied at the same time as vaccination.
  • A post-mortem revealed multifocal pale lesions on the surface of both kidneys. No other significant findings were noted and a complete sample set was collected for laboratory examination.
  • Histopathology showed a severe acute multifocal vasculitis and subacute subcortical multifocal nephritis.
  • These findings were suggestive of MCF, which was confirmed by PCR testing of a blood sample.
  • MCF typically affects single animals in a herd. Other common clinical signs include thick nasal discharge, cloudiness of the eyes and diarrhoea.

Brucella abortus exclusion

  • A cattle herd in the South West with a history of pregnancy rates of <80% was investigated last year and testing found a selenium deficiency and neosporosis.
  • Some infected animals were culled, selenium supplements were given, and the bulls were fertility tested, but poor pregnancy rates were experienced again (<70%).
  • Blood samples were taken from 10 heifers and nine cows. Brucella abortus testing was negative but ELISA testing of vaginal swabs for Campylobacter venerealis IgA was positive. Testing also revealed pestivirus was present in the herd but no persistently infected animals were detected.
  • Retesting selenium levels showed a deficiency was still present.
  • Selenium deficiency can lead to infertility, abortion, weak stillborn or lethargic calves and can increase the incidence of cystic ovaries, retained placentas, metritis, delayed conception, erratic, weak or silent heat periods and poor fertilisation.
  • Neospora is normally associated with abortion from three months onwards, but most commonly between four and six months gestation.