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Foot-and-mouth disease
With many sheep producing regions across Australia receiving rainfall through January to March, Animal Health Australia (AHA) is reminding producers to be vigilant about virulent footrot. Virulent footrot spreads and expresses in the warm and moist conditions which are prevalent in many regions right now.
AHA’s Biosecurity Extension Manager, Dr Sophie Hemley, explained that footrot is most common in spring and in wet autumns, and cases have been steadily on the rise since late last year.
Dr Hemley, who is also a veterinarian and a sheep farmer, encourages producers to continue to take proactive biosecurity action to prevent and eradicate outbreaks in their own flocks.
“Footrot can only develop in sheep and goats when environmental conditions favour bacterial spread and when the bacteria, Dichelobacter nodosus is present,” she explained.
“Average daily temperatures of 10°C or more for 4–5 days, enough moisture on the pasture to wet your boots when you walk across it in the morning, and adequate pasture length and density all contribute to an optimal spread environment.”
There are multiple strains of D. nodosus and the virulence (or infectivity) of the strain will determine the severity of expression. Benign strains of footrot normally only cause minimal inflammation between the toes and will self-resolve, whereas virulent footrot will progress to break down the connective tissue that attaches the hoof horn to the underlying structures of the foot.
Virulent footrot essentially presents with under-running of the sole and in some cases the sole will fall off.
“It can be difficult to differentiate benign and virulent footrot during the early stages of disease; because of this if you suspect your sheep or goats have any signs of footrot I would encourage you to contact your vet,” Dr Hemley said.
“Early detection helps you in the long run by reducing spread and by giving you more options to work with your vet to manage the situation.”
Cases of virulent footrot have become a hot-button issue in New South Wales and South Australia, where Dr Hemley and fellow Biosecurity Extension Manager Dr Emily Buddle work with producers to implement and improve on-farm biosecurity measures on their own properties.
Dr Hemley says that, for producers fortunate to be free of footrot, managing the risk of infection is of the utmost importance.
Simple measures that many producers already are doing, such as maintaining adequate external fencing, requesting a Health Declaration when purchasing in and isolating new livestock, Dr Hemley explains pays significant dividends for producers eager to manage the risks of footrot and other diseases.
“Although in some situations there may be a few treatment options available to lessen the impact of virulent footrot, in my experience the most successful way to eradicate the disease is to cull infected sheep.”
“This can be a challenging prospect when considering rebuilding your flock, so we encourage you to focus on preventing the disease from crossing onto your property. If you are ever in doubt keep animals isolated and ask your vet.”
Virulent footrot is a notifiable disease is both New South Wales and South Australia, meaning producers experiencing cases are required to report this to the state governments’ animal health authorities.
Producers wanting more information on biosecurity for their sheep can visit the Farm Biosecurity website.
