WA Livestock Disease Outlook - for producers

Recent livestock disease cases in WA

Hendra virus ruled out in two cases of neurological signs in horses

• In June, there were two separate cases of neurological signs in horses in which Hendra virus was ruled out.
• In the first case, a 20-year-old pony had been blind on one side for a week, had a wobbly gait, and was walking around aimlessly in circles. These signs progressively worsened, and the horse became feverish, depressed and stopped eating. The horse was not vaccinated for Hendra virus and there was no history of travel. There was one other horse on the property, as well as some sheep, none of which were displaying any clinical signs.
• In the second case, a single horse agisted with 30 others displayed dullness, wobbly gait, breathing difficulties, nasal discharge, bloody oral discharge, and was off its food. The horse also had an extended head and neck. The horse was penned in an area where flying foxes were roosting. No other horses at the property were unwell, and the horse did not have a current Hendra virus vaccination. 
• In both cases, the owners contacted a private vet, who collected samples to test for Hendra virus. Fortunately, both horses tested negative to Hendra virus and other emergency diseases of horses.
• In the first case, the signs were likely due to a tumour or infection in the brain, and in the second case, a tooth abscess was suspected.

Hendra virus in brief:

• There has never been a case of Hendra virus in horses or people in WA, but flying foxes (fruit bats) in northern WA have shown evidence of exposure to Hendra virus and present a risk to horses where they have close contact.
• The disease is generally fatal in horses. Rarely, the virus can spread from an infected horse to people in close contact, and causes serious disease and sometimes fatalities.
• Horses with Hendra virus generally deteriorate quickly. Other signs include fever, dullness, difficulty breathing, and neurological signs such as wobbly gait, lack of coordination, circling and muscle twitching. 
• If your horse shows any of these signs, and may have had exposure to flying foxes, or to other horses that have had exposure to flying foxes, call your vet or the Emergency Animal Disease hotline on 1800 675 888 immediately. Minimise your contact with the horse until you have received veterinary advice. Depending on the level of risk, your vet may need to take extra personal safety precautions in order to examine and treat the horse.
• For more information on Hendra virus, including how to reduce the risk of your horses becoming infected, see the Hendra virus webpage.

Private vet helps rule out foot-and-mouth disease in calves in the South-West

• This month, a producer reported that in their herd of 150 two-month-old Angus cross calves, one had died and another had a fever, nasal discharge and difficulty breathing.  
• The producer contacted their private vet, who performed a post-mortem on the dead calf, and found froth in the airways and lungs and ulcers at the back of the mouth.
• The vet submitted samples to the DPIRD laboratory, suspecting that the most likely cause was infectious bovine rhinotracheitis or calf diphtheria (necrobacillosis). However, as the calves also had similar signs to foot-and-mouth disease, which can include blisters and ulcers in the mouth, lameness, depression, lack of appetite and sudden death in young animals, DPIRD also tested for the reportable diseases foot-and-mouth disease and vesicular stomatitis. Both of these diseases were ruled out through testing. 
• DPIRD paid the laboratory fees as the investigation was able to provide evidence of Australia’s freedom from a trade-sensitive disease. 
• Testing showed that the disease was likely due to a bacterial infection with Bacteroides pyogenes. The vet was then able to work with the producer to manage the disease. Obtaining a diagnosis for any disease in your stock is essential to be able to manage and prevent disease in the future.
• To familiarise yourself with the signs of foot-and-mouth disease, watch this short video.
• Report any unusual illness or deaths in your stock to your private vet, a DPIRD vet or the Emergency Animal Disease hotline on 1800 675 888. If an emergency disease does occur, calling a vet provides the best chance of early detection and eradication – protecting your industry. 
• For information about the range of subsidies available to support disease investigations, see the surveillance incentives for WA livestock producers webpage.

Figure 1: Drooling is a key sign of foot-and-mouth disease in cattle. Always call a vet if you see cattle drooling.

Neurological signs in Merino hoggets in the Wheatbelt

• Always call a vet if you see unexplained changes in behaviour or neurological signs in livestock, as they may be signs of a reportable disease that has trade or human health implications. 
• Last month, a DPIRD vet was contacted by a Wheatbelt producer who reported neurological signs in one-year-old Merino ewe hoggets. Of their flock of 200, one had died and other animals had been found separated from the group, dull, staring into space, with some appearing blind.
• The DPIRD vet conducted an on-farm investigation and post-mortem of the dead ewe. It was in good body condition, with no unusual findings on post-mortem.
• Samples submitted to the laboratory showed degradation of the brain characteristic of polioencephalomalacia (PEM) (‘softening of the grey matter in the brain’).
• The most common cause of PEM in WA is thiamine (also known as vitamin B1) deficiency. Most outbreaks of PEM are sporadic and affect only a couple of animals in a mob, but death rates of up to 10% have been reported. In WA, the disease occurs throughout the year, but it is most common when there is a sudden change to the feed composition such as during spring and autumn.
• For more information on PEM, including treatment, see our PEM webpage.

In late winter/spring, watch for these livestock diseases: