With spring lambing underway, sheep producers are being urged to revise their tail docking techniques.

Findings from a study by Dr Joan Lloyd released in a report from Meat and Livestock Australia (MLA) showed a tail cut too short put lambs and sheep at greater risk of developing arthritis

Livestock Biosecurity Network Victoria and South Australia regional manager Pat Kluver said producers needed to make sure they were docking tails at the correct length, because arthritis was costing the sheep industry about $39 million a year through slow growth rates, deaths and trimming at the abattoirs.

Dr Kluver said historically, tails had been cut too short, and the MLA report indicated 20 per cent of sheep had their tails cut shorter than the recommended length.

It is recommended by industry experts that tails be cut no shorter than the third palpable joint.

But Dr Kluver said some breed societies and districts had recommended tails be shorter than this.

"There are a lot of reasons to get the tail length right, and there are not a lot of reasons to get it wrong," he said.

Dr Kluver said the third palpable joint was the ideal point to dock the tail — not only was it easily identified due to it being a thinner part of the tail, but it also healed faster, so the incidence of infection was reduced.

He said tails docked shorter could result in a larger wound, slower healing and a higher level of infection.

Dr Kluver said septic arthritis was caused by bacteria entering the body, usually through a wound, and lodging in the joint.

Correct tail length reduces arthritis by one third

The MLA report highlighted that the risk of arthritis in sheep with shorter tails was one-and-a-half times that of sheep with correctly docked tails.

"This means if you stop docking tails short, you will reduce the level of arthritis by about a third in your lambs," Dr Kluver said.

The report identified that as well as marking and mulesing, other causes of arthritis included post-dipping arthritis, caused by poor dip hygiene and dipping within two weeks of shearing before wounds had healed.

"Septic arthritis is usually quite obvious and painful, as it's a crust producing arthritis and the animals cannot bear weight on that limb," Dr Kluver said.

"It is very painful, and they will be lame, so if producers identify it early enough it can be treated with antibiotics."

He said lambs affected by arthritis were on average three kilograms lighter than their equivalent cohort at processing.

"Some lambs will become unfit to market, and for every percentage of sheep that we see at the abattoir with arthritis, we think there would be equal amounts still on land that are unmarketable," Dr Kluver said.

At the abattoir, lambs found infected with arthritis were trimmed to the next clean join, often resulting in the trimming of valuable cuts and an average loss of 750 grams per carcass.

If there are more than four joints infected by arthritis, the whole carcass is condemned.

Dr Kluver said the level of arthritis found at the abattoir was between 1 and 2 per cent, a small but significant level for the economic impact it had across the industry.

Breech strike and other health impacts

There are a number of other potential health impacts for lambs and sheep when tails are cut too short.

Dr Kluver said when tails were cut too short it could damage nerves in that area, which could result in the animal's inability to raise its tail properly while defecating, leading to an increased incidence of breech strike.

He said sheep with their tails cut too short were two to three times more likely to be affected by breech strike.

Rectal prolapse was also seen in lambs with short tails, as the muscles were weakened around the rectum, at around four times the level as those with tails docked at the recommended length.

The chance of squamous cell carcinoma was also increased, as the vulva and perineum were exposed to sunlight, and after sheep were five to six years old the incidence of this cancer increased significantly.

'Get it right and it is right for life'

Sheep classer and livestock consultant Michael Elmes, of Narrandera in New South Wales, said sheep producers needed to mark lambs in clean and hygienic conditions for optimal animal health.

"Cleanliness is paramount at lamb marking when it comes to the instruments and the drop zone producers are using," he said.

"I suggest producers put down clean straw in the drop zone to reduce infection from dirt.

"The drop zone should be changed regularly. Don't use the same place year in and year out."

Mr Elmes said it was imperative producers cut tails at the correct length to ensure the longevity of their ewes.

"Once you cut the tail, that is it. If you get it wrong, it is wrong for life," he said.

"And if you get it right, it is right for life. It is a very critical operation."