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ParaBoss News - July 2020 - Feature Articles

Moniezia expansa segments. Image: Deb Maxwell.
Moniezia expansa segments. Image: Deb Maxwell.
Hairy maggots cause extensive damage. Image: NSW DPI.
Hairy maggots cause extensive damage. Image: NSW DPI.
There is a reason samples are collected 10-14 days post-drench. Image: Gary Fry.
There is a reason samples are collected 10-14 days post-drench. Image: Gary Fry.

Fast Fact

Tapeworms, ain’t tapeworms

We normally imagine tapeworms as long fettucine-like worms, appearing as small white segments in the faeces. However, they have a completely different cyst-like stage in another host as well.  Sheep can carry different tapeworm species—and different stages of each. Sheep host the worm stage of the common sheep tapeworm, Moniezia expansa, a large, obvious and virtually harmless parasite; treatment is rarely recommended (the cyst-stage is in a tiny soil mite).

But sheep also host the cyst stage of the Hydatid tapeworm, Echinococcus granulosus. Again, it is harmless to sheep and treating sheep for tapeworm won’t kill this cyst stage.

It’s dogs that need the treatment. Dogs carry the worm stage of the Hydatid tapeworm in their intestines if they have eaten hydatid cysts in the raw offal of sheep (or goat, cattle, roo or deer), and the tapeworm segments with eggs then pass in the dog’s faeces onto the ground to reinfect sheep. When humans, instead of sheep, accidentally ingest those eggs, serious illness can result from the cysts that can develop in the liver, lungs and, sometimes, the brain. For tapeworm: worm the dog, not the sheep.

Feature articles

Checking for drench resistance: why collect faecal samples 10–14 days post-drenching?

by Dr Lillian Mukandiwa

When a drench resistance test is done, samples are checked 10–14 days after drenching. Why then, and not sooner or later?

The renowned veterinary parasitologist, Dr Brown Besier, shared his knowledge with our former Technical Manager, Lillian Mukandiwa, who prepared this article for ParaBoss. >> Read more about the time of sample collection to test for drench resistance.

Which blowflies strike first and which are worse?

by Deb Maxwell, ParaBoss Executive Officer

Lucilia cuprina initiate over 90% of strikes; Calliphora start the rest. Chrysomya don’t start any, but cause the worst damage.

Lucilia and Calliphora are “primary” strike flies because they initiate strikes on sheep skin damaged by fleece rot, urine stain, dag or wounds.

Chrysomya genus are “secondary” because they only strike an existing strike wound.

The primary fly maggots are smooth and feed on the surface of the skin, whereas Chrysomya maggots are hairy or spiky and they also burrow under the skin, turning it dark and hard and making the sheep noticeably sicker.

Large Lucilia strike wounds  (e.g. the whole rump area) can generally be successfully treated (although the sheep will suffer a severe setback and have a break in their fleece), whereas the same size wound from Chrysomya is more likely to be fatal. Susceptible sheep should be checked frequently during times of high flystrike-risk. >> Read more about blowfly maggots.

The lousy late-pregnant pregnant ewe

by Deb Maxwell, ParaBoss Executive Officer

I had a discussion recently with a grazier who had found himself in a very unwelcome position. In his lice-free flock for over 25 years, he unexpectedly found a handful of his soon-to-lamb maiden ewes were rubbing—just a little. A thorough inspection by his daughter (who has good eyesight) of the slightly scruffier looking sheep finally revealed just a few lice on the seventeenth sheep examined (it pays to be thorough and to persevere).

The critical periods we discussed were the time to lambing, time since last shearing and to next shearing, and the time for any particular treatment to kill all of the lice, as well as his equipment and confidence to effectively treat.

I suggested he use the LiceBoss Ewe-lamb Treatments Tool, which asks a series of simple questions to come up with the best option to eradicate the lice under that situation. Sometimes, of course, such as when the ewes are already a month off shears and on the point of lambing, eradication won’t be possible until the following shearing. >> Read more about lice management in late-pregnant or lambing ewes.

Why are goats more likely to carry drench-resistant worms than sheep?

by Deb Maxwell, ParaBoss Executive Officer

Goats metabolize some drenches more rapidly than sheep. Using the sheep dose rate on product labels generally results in the goat being under-dosed and this leads to survival of more worms that can resist drenches. But take care! Increasing the dose too much can be dangerous, with some drenches having small safety margins.

Most goat owners do not realise that using a sheep-only drench, or indeed increasing the dose above the label instructions is illegal in most states of Australia without a veterinary prescription. It’s why WormBoss doesn’t publish the recommended dose rates, which vary with the particular drench groups and products. And your vet is also obliged to include information with the prescription, such as withholding periods. >> Read more about correct and legal use of drenches for goats.

Goats are likely to carry drench-resistant worms.Image: Berwyn Squire.
Goats are likely to carry drench-resistant worms.Image: Berwyn Squire.
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