Treatment of struck sheep
The recommended way to treat flystruck sheep:
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1. Shear struck wool and a 5 cm barrier of clean wool around the strike close to the skin to remove maggots.
- Unless wool is shorn off it is likely that maggot trails will be missed and sheep will remain struck.
- Machine-shearing is generally better than hand-shearing.
2. Collect the maggot-infested wool into a maggot-proof (plastic) bag and leave the bag in the sun for a couple of days to kill all maggots.
- This breaks the life cycle, which is especially important if the maggots have survived on sheep that have had a preventative product applied previously and these maggots are resistant to the product.
- Don’t rely on registered flystrike dressings to kill maggots—some are incapable of killing large maggots and many maggots escape treatment by dropping from the sheep and burrowing into the soil before the insecticide can be applied. Unless maggot infested wool is collected and bagged, most maggots will survive and pupate and come back as adult flies.
3. Apply a registered flystrike dressing to the shorn area to prevent re-strike.
- If necessary, these treated sheep may be jetted or backlined along with other susceptible sheep to provide long-term flystrike protection. Ensure a product with a suitable withholding period is chosen.
- Note: A product registered as a flystrike "dressing" is different to a preventative. A dressing has two purposes: to kill remaining maggots and to prevent re-strike as the affected area is drying and healing. Where maggots remain, the two common flystrike preventatives, dicyclanil (e.g. CLiK) and cyromazine (e.g. Vetrazin), when applied alone, are not suitable on welfare grounds, as maggots will take up to 4 days to die. Where maggots may remain, a dressing that rapidly kills maggots should be applied; these contain either ivermectin, spinosyn or organosphosphates. There is a high level of resistance to the organophosphate, diazinon, which may reduce its effectiveness in killing larger larvae. One of the dicyclanil or cyromazine preventatives may also be applied if longer ongoing protection is required.
4. Remove struck sheep from the mob.
- Leaving struck sheep in the mob attracts more blowflies.
- Moving struck sheep to a ‘hospital’ paddock allows closer monitoring of recovery and reduces the risk to the rest of the mob.
5. Cull struck sheep from breeding programs
- Susceptibility to flystrike is heritable and repeatable. Sheep that have been provided suitable management and/or chemical protection, but have become struck when most of their flockmates have not are best culled from breeding programs to improve both current and future flock resistance to flystrike. They can be maintained with extra protection as dry sheep.
- Adult sheep that sustain repeated flystrike (crutch or body) are best removed from the property.
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Video of best practice treatment of flystruck sheep.
Notes on best practice treatment of flystrike.