WA Livestock Disease Outlook - for vets

Recent livestock disease cases in WA

Sudden death in Angus calves in the South-West

• Four six-month-old Angus calves died suddenly from a mob of 53. The calves had been grazing pasture. No deaths were reported from another mob of cows on the property.
• The carcasses of the calves had bloated very rapidly and were leaking unclotted blood from all orifices.
• As the appearance of the carcasses was suspicious for anthrax, the vet did not carry out a post-mortem. Samples were collected to exclude anthrax as the cause of death.
• Blood smears, blood swabs and samples of soil mixed with leaked blood all tested negative for Bacillus anthracis on immunochromatography, bacterial culture, and special stains.
• Key considerations: Anthrax is a serious zoonotic disease. Producers should be advised not to touch or move the carcass until anthrax exclusion testing has been conducted. Post-mortems should not be performed and personal protective equipment (PPE) should be worn when collecting samples.
• Testing ruled out anthrax as the cause of death. Testing was subsidised, as anthrax is a reportable disease. Read more on DPIRD’s website on anthrax and see the DPIRD veterinary sampling guide for anthrax.
• Based on the history and once anthrax had been ruled out, the likely cause of death was thought to be blackleg, as the calves had not been vaccinated. The remaining calves were vaccinated and no further deaths occurred.
• Read more on vaccinating against cattle diseases.

Photosensitisation in 100 Merino cross lambs

• Three-month-old Merino cross lambs were affected by photosensitisation, with irritation and swelling around the face, and some lambs with sloughing of the tips of the ears.
• 100 lambs were affected from a mob of 600.
• Lambs were grazing mixed pasture containing clover, grasses and broadleaf weeds.
• Post-mortem examination, histopathology and biochemistry were not consistent with hepatogenous photosensitisation.
• Primary photosensitisation was the likely cause. The producer was advised to submit clover and grasses for photodynamic assay. See the DPIRD photosensitisation webpage for more information.
• Differential diagnoses for photosensitisation include scabby mouth, and the exotic diseases sheep pox, bluetongue disease and foot-and-mouth.
• Submission of a complete sample set allowed reportable diseases to be excluded as the cause of the facial lesions. Testing was subsidised as the results will contribute to demonstrating WA’s ongoing freedom from these trade-sensitive diseases.
• See the DPIRD webpage Sampling and post-mortem resources for vets for best practice sample selection and submission. Alternatively, contact your DPIRD field vet or the DPIRD duty pathologist on +61 (0)8 9368 3351.