Veterinary Pain Relief for Sheep Procedures

Mulesing Overview

• Mulesing involves the surgical removal of wool-bearing skin near the breech of sheep to prevent flystrike, caused by feces and urine attracting flies.
• Scar tissue that forms post-surgery does not grow wool, making it less appealing to flies, thus reducing flystrike incidence.
• Commonly practiced in Australia, particularly among highly wrinkled Merino sheep; considered by some as a skilled surgical task.

Welfare and Controversy

• Australian National Farmers Federation claims mulesing is vital to prevent up to 3 million sheep deaths from flystrike annually.
• Australian Veterinary Association acknowledges welfare concerns but accepts mulesing in the absence of more humane alternatives.
• Animal rights organization PETA vehemently opposes mulesing, labeling it cruel and suggesting more humane methods like dietary changes and spray washing.

Historical Context

• Mulesing was developed after rancher John Mules discovered that accidentally cutting a ewe's skin healed with smooth scar tissue, preventing fly attraction.
• Mulesing techniques have evolved since their inception in the early 1930s; initial practices on mature sheep shifted to lambs for quicker recovery.

Australian Sheep Blowfly

• The invasive Australian sheep blowfly is a significant threat, attracted to soiled wool and open wounds.
• Flystrike can lead to severe systemic infections and high mortality rates in affected sheep.

Procedural Details

• Conducted by accredited professionals, mulesing is performed under restraint, removing loose skin while avoiding muscle damage.
• Antiseptics and pain relief are not mandated by law, although products like Tri-Solfen are used for pain management.

Comparison with Crutching

• Mulesing permanently alters the skin to provide long-term resistance against breech flystrike, while crutching only temporarily removes wool that attracts flies.
• Crutching must be repeated regularly, while mulesing significantly reduces flystrike likelihood.

Opposition and Regulatory Changes

• Activists contend mulesing is inhumane and exacerbates genetic susceptibility to flystrike.
• International brands have boycotted Australian Merino wool due to mulesing practices.
• Australian Wool Innovation initially pledged to phase out mulesing by 2010 but later abandoned this commitment amid pressure from animal welfare groups.

Alternatives to Mulesing

• Freeze Branding (Steining): A new technique using liquid nitrogen to freeze skin near the tail, preventing wool regrowth and fly attraction; shown to cause less long-term pain than mulesing.
• Breeding Programs: Selective breeding of plain-bodied Merino sheep has shown lower susceptibility to flystrike, further reducing the need for mulesing.
• Non-surgical Methods: Research is focused on insecticides, topical treatments, biological control of blowflies, breech clips, and natural repellents like tea tree oil.

Flystrike Management

• Flystrike significantly impacts sheep welfare and industry economics, costing around $280 million annually.
• Successful management requires monitoring both environmental conditions and sheep susceptibility.
• The Australian blowfly (Lucilia cuprina) is the main instigator of flystrike, initiating 90% of cases, with its life cycle culminating in a rapid development to maturity.

Conclusion

• Effective flystrike management balances animal welfare and industry viability, with ongoing efforts to find humane alternatives to mulesing and improve sheep breeding practices.### Life Cycle and Behavior of Flies
• Adult flies rarely travel more than three kilometres from their hatching site.
• Female flies require protein for reproductive organ maturity and before egg-laying.
• Common protein sources include carcasses, manure, and existing strikes.

Conditions Favoring Flystrike

• Presence of primary species, particularly the Australian sheep blowfly (L. cuprina).
• Ideal temperatures for flies range from 15 to 38 degrees Celsius.
• Recent rain must keep sheep moist for about three days to sustain fly larvae.
• Suitable sites on sheep, such as wrinkles and areas with faeces or urine, attract flies.
• Wind speeds below 9 km/h promote fly dispersal, while above 30 km/h significantly reduce activity.

Importance of Monitoring

• Low numbers of L. cuprina can still lead to significant flystrike under optimal conditions.
• Example: At Mount Barker Research Station in September 1978, a low number of flies coincided with a high strike incidence (62% of annual total).

Seasonal Activity Patterns

• Most blowflies are active in spring and summer, with higher captures in these seasons compared to autumn.
• Studies show L. cuprina is inactive below 15°C and most active between 26°C and 38°C.

Susceptibility of Sheep to Flystrike

• Susceptibility is influenced by environmental conditions and sheep management strategies.
• Best-case scenarios include plain-bodied sheep, good worm control, and regular monitoring.
• Worst-case scenarios involve highly wrinkled sheep, poor pasture hygiene, and neglect in monitoring.

Management Strategies to Reduce Flystrike Risk

• Prevention is more cost-effective than treatment.
• Short-term options include strategic chemical applications, crutching, and shearing.
• Long-term solutions involve genetics, aiming to breed for reduced dags and wrinkles.

Controlling Worms and Dags

• Scouring, leading to dags, is primarily caused by worm infestations.
• Regular worm egg counts (WEC) help manage worm burdens effectively.
• Dag scores range from 1 (no dags) to 5 (extremely daggy), affecting susceptibility to breech strike.

Crutching and Shearing Practices

• Both practices can provide protection from breech strike for up to six weeks, with protection duration shortened if sheep are scouring.
• Timing is crucial: aligning crutching/shearing with the start of the fly season enhances effectiveness.
• Pre-lambing crutching is vital for reducing udder strikes and facilitating easier suckling.

Tail Docking Techniques

• Proper tail docking at the third palpable joint reduces dags and urine staining; overly short docking may increase rectal prolapses.
• The Te Pari Patesco knife is a newer tool for effective tail docking, aiming to enhance bare skin area and reduce fly attraction.

Mulesing Guidelines

• May not be necessary with breeding for fly and worm resistance.
• Regulations stipulate trained personnel must perform the procedure, with pain relief required for certain age groups.

Chemical Application for Flystrike Control

• Effective chemical use involves understanding fly biology, product choice, and correct dosage based on the heaviest animals.
• Classes of registered chemicals include insect growth regulators (IGR), macrocyclic lactones (ML), and spinosyns.

Occupational Safety Measures

• Follow safety labels, wear protective gear during chemical application to prevent exposure to harmful substances.

Withholding Period Considerations

• Understand wool and meat withholding periods when applying chemicals to prevent residues.

Long-term Genetic Solutions

• Breeding for resistance focuses on selecting sheep with desirable traits linked to flystrike resistance, such as low wrinkle and dag presence.
• Genetic selection can be applied within both the existing ewe flock and among lambs for future breeding programs.

This quiz covers the use of Tri-Solfen for pain relief during veterinary procedures involving sheep, specifically around mulesing practices. It highlights the approval process for the product and its implications for veterinarians and sheep industry workers. Test your knowledge on the application and effects of pain relief measures in livestock management.