Johne’s disease in sheep (also referred to as Ovine Johne’s Disease or OJD) is an infectious, incurable wasting disease caused by the bacteria Mycobacterium paratuberculosis.
OJD usually enters a flock through new infected sheep which are introduced (including strays), the consumption of pasture or drink water contaminated by faeces from infected sheep/other susceptible species, or co-grazing with infected cattle or other species infected with Johne’s disease such as goats and alpacas.
Clinical signs of OJD are not easily detectable as they are insidious and progressive. Infected sheep progressively lose weight and are malnourished which usually leads to death or euthanasia up to eight months after clinical signs are first observed. The most common sign of OJD is a distinct ‘poor’ tail end of the mob.
Due to long incubation periods, healthy looking animals can spread the disease bacteria before being clinically affected. The level of disease is influenced by management practices, environment, rainfall and stocking rates. This disease is more common in high rainfall, high stocking environments.
The SA Sheep Industry Fund support the South Australian OJD Management Program. This program is managed by PIRSA and aims to reduce the economic impact of OJD by:
- Encouraging producers to voluntarily investigate and manage Johne’s disease in their flocks
- Encouraging the declaration of OJD risk for all sheep sold or entering SA by using the National Sheep Health Declaration
- Improving industry awareness of OJD risks and its management through education
- Promoting low-risk trading and management practice
Producers can investigate and monitor OJD in their flock by requesting an inspection when consigning sheep to Thomas Foods International (TFI) abattoirs, or through on-farm testing by a private veterinarian or PIRSA staff.
For more information about OJD, visit the PIRSA website
For more on the OJD management program, visit the PIRSA website
Lice in sheep causes major economic loss to the industry by reducing the quality and quantity of wool and increasing the cost of labour and chemical treatments.
Most new lice infestations start from contact with other lousy sheep, which may be purchased (including rams), stray sheep from other mobs or properties.
C auses of continuing infestations include split shearings and treating ewes with lambs at foot or pregnant ewes due to lamb within 6 weeks of treatment, and failure to eradicate lice on a previous treatment.
In the early stages of an infestation louse numbers increase very slowly and it may take many months for the infestation to become obvious. When introducing purchased or returning strays to a mob, careful inspection and regular monitoring will prevent new infestations, save production loss, reduce residues and save costs.
Footrot is a contagious bacterial disease in sheep caused by the bacterium Dichelobacter nodosus (D. nodosus). Footrot causes inflammation of the interdigital skin and potential underrunning of the hoof.
In South Australia, footrot is a notifiable disease.
Any suspicion of infection must be reported immediately.
Footrot can cause significant economic loss to producers by reducing fertility, wool growth, growth rates and limiting market opportunities through sheep sales.
Controlling and eradicating footrot can be costly and time consuming however the long-term benefit of eradication far outweighs the cost.
For more information, visit the PIRSA website.
Ovine Brucellosis (OB) is a venereal disease in sheep which can lead to infertility, increased lambing periods, abortions and weak lambs.
Transmission occurs during mating and ultimately affects the reproductive organs, particularly in rams. Producers should be aware of the OB status of any rams they are purchasing as the disease is incurable and will result in the animals being culled.
For more information, visit the PIRSA website