Country Vet
Flystrike is easy to prevent, but vets still see it far too often.
6 ways to prevent flystrike WARNING: contains graphic images
Flystrike is a nasty condition commonly seen in sheep and alpaca, but it can affect any animal, including rabbits, poultry, cats, and dogs. It's simply, grossly, an infestation of maggots. The most common culprits are blowfly species, which lay eggs on the warm flesh of the animal. Maggots hatch and feast on the flesh, quickly causing large, deep wounds, extreme pain, infections, and in the worst cases, death.
It's primarily seen during warm, humid weather when flies are attracted by the scent of hot, damp animals.
Hot weather can also significantly speed up the flies' lifecycle, which means an animal can be seriously affected in just a few days.
In the South Island, the peak risk season is November to April; in the more humid North Island, it's from October to May.
It's difficult to spot an animal with flystrike from a distance, which is why it's important to check stock up close, daily.
FLYSTRIKE is horrendous and debilitating to an animal. It's easily preventable, but vets still see it a lot.
Some animals don't receive the appropriate preventative care. We also see flystrike even though stock were supposedly treated. These are some of the reasons why.
1 Shearing
This is the most critical thing you can do to avoid flystrike. Shearing is usually done:
• in June to help prevent winter lice;
• at the start of summer, to prevent flystrike. Shearing helps to keep sheep clean, cool, dry, and dag-free.
2 Prevent diarrhoea
Flies are attracted to moist, smelly areas on animals, and pooey backsides are the perfect target. If you can prevent diarrhoea, you significantly decrease the risk of flystrike. It's essential to design and follow a quality drenching program.
If an animal does get diarrhoea, trim off any smelly wool. If diarrhoea doesn't clear up quickly after drenching, get your vet to rule out other causes.
3 Tail docking
Docking tails in young lambs prevents diarrhoea from accumulating around an animal's back end.
Docking means applying a ring between the vertebrae, below the level of the vulva, so the tail is still long enough to protect the genitals and sweep away flies.
Tail docking is recognised as a painful procedure. Ideally, it's done when lambs are 1-2 weeks old. If lambs are over six months old, it must be performed under a vet's supervision, using appropriate pain relief. However, pain relief is highly recommended for animals of any age.
Pain relief options are available through your vet, either an injection (at the clinic) or a liquid you can give to your lambs if you're docking them at home.
4 Closely monitor wounds and sick stock
Any animal that suffers a wound during the warmer months is at risk of flystrike. Blood, pus, or weepy fluid is the ultimate open bar for a fly.
Stock suffering from a disease are often lethargic, which also makes them a prime target. If you have a sick animal, monitor it closely and check its entire body regularly, including the belly, in the ‘armpits,' and the tail region.
5 Use insecticides
The appropriate use of chemical insecticides is a crucial part of preventing flystrike, but they're often applied incorrectly.
Most people on blocks use products that come with a spray applicator. Carefully follow the instructions, which are usually to apply a dose along the back and rear end – don't overdo it, as too much can be toxic to the sheep.
These products work best (for up to 12 weeks) when applied about four weeks after shearing. If you apply a preventative insecticide on the day of shearing, protection may not last very long, depending on the breed, wool type, and wool length.
Even if you apply an insecticide, you still need to monitor your stock daily for signs of flystrike.
6 Control the environment
Blowflies love heat, but their eggs also need moisture to hatch. You may find there are certain humid ‘hotspots' on your block, such as sheltered gullies. Windy areas are a safer environment during high-risk weather such as warm, rainy and/or humid summer days.
Make sure you bury dead animals promptly to avoid feeding the fly population.
Tail length is important. Dock too short or long, and your sheep are more prone to flystrike.
Set out fly traps around your block. They're not going to control a soaring fly population, but they're a useful tool to alert you when flies are hatching from the soil, indicating the ideal time to shear and/or use a preventative treatment.
7 Choose the best sheep for your block
If you live in a humid region, choose sheep breeds that are less prone to flystrike, such as those with fine wool or self-shedding breeds.
However, also remember that during high-risk times, even self-shedding breeds can be struck by flies, so always monitor stock closely, whatever the breed.