Review of Epidemiology and Management of Arthritis in Lambs in Australia

Summary

A series of surveys was undertaken to determine the incidence of arthritis in prime lamb sheep in Australia. Data was collected from AQIS and survey data was collected from a sample of sheep producers, veterinarians and diagnostic laboratories. In addition the current literature was reviewed. Arthritis is sheep may be caused by any of three groups of organisms. These groups are Erysipelothrix, Chlamydia and pyogenic bacteria. Each group is responsible for approximately one third of the cases that are submitted for diagnosis. The percentage of total condemnations of carcases as a result of arthritis is 0.017% in lambs and 0.019% in adult sheep at slaughter. Partial condemnations are 3.9 times higher than total condemnations. Sheep producers report that there is an average of approximately 0.63% of lambs affected with arthritis observed on properties with up to 70% of these either destroyed on the property or dying. 
Two interesting findings were found in the abattoir data which require further investigation. The first is that the incidence in adult sheep is the same as that seen in lambs. The second finding was that the percentage of sheep condemned with arthritis in Victorian abattoirs was almost twice as high as that in any other state of Australia. The economic loss to the sheep industry was calculated to be $18,000,000 annually. The losses were the result of total and partial condemnations at abattoirs, sheep destroyed on properties, the cost of lower feed conversion in affected sheep, the costs of treatments and preventative strategies, and the cost of additional meat inspection resources required to inspect carcases. 
Very few cases of arthritis are submitted for definitive diagnosis. Most sheep producers have stopped attempting any treatment because of the low success rate. Several preventative strategies are employed which include the use of a vaccine against Erysipelothrix, and the use of antibiotics either as a preventative or for treatment of new clinical cases. Although most cases of arthritis are associated with wounds in sheep such as occurs at marking or shearing, some cases do occur in sheep when concentrated around grain feeders. The requirements of good hygiene have not been defined, although this is the most common advice given to reduce the incidence of the disease.