Sheep measles is the cystic (larval) stage of a dog tapeworm. The parasite confusingly has two names with the cystic stage in sheep called Cysticercus ovis and the adult tapeworm stage in dogs calledTaenia ovis.
The sheep measles cysts are usually found in the muscle of sheep, including the heart.
Abattoir meat inspectors detect oval, white/cream coloured cysts up to 12mm wide. If cysts have been present for some time they may become hard (calcified).
The condition does not affect sheep health or production on farm.
Condemnations – if five or more cysts are found the entire carcass is condemned.
Trimming – cysts must be trimmed from the muscle. This results in a significant reduction in carcass/dressed weight.
HOW DO SHEEP GET SHEEP MEASLES?
Sheep measles occurs when sheep ingest tapeworm eggs from contaminated pastures. For the completion of the tapeworm’s life cycle two hosts are required. Different stages of the parasite life cycle occur in each of the following hosts:
An ‘intermediate (sheep) host’ - or goat.
Sheep are infested when they graze pasture contaminated with dog tapeworm eggs.
Once ingested the eggs hatch and the larvae form cysts in the muscle.
A ‘definitive (dog) host’ (dingos and foxes are also possible definitive hosts).
Dogs/foxes/dingos are infested when they eat raw meat and offal containing cysts.
Worm your dog/s - worm all dogs on the property MONTHLY with a tapewormer containing the active ingredient praziquantel.
Worming must be monthly (not every three months) as the parasite life cycle is 35 days, worming needs to be before the parasite completes its life cycle to prevent worms laying eggs that will contaminate pastures. Worming monthly is not dangerous to your dog.
Worm all farm dogs and ensure all dogs coming onto the property are appropriately wormed (within the last month) - including those belonging to shearers, truckies and other contractors, friends or family who visit, retired working dogs and pets.
Ensure you dose according to the weight of the dog. Round the dose up, not down, to the nearest tablet or half tablet.
It is cheapest to purchase wormers in bulk (from rural resellers or online).
Every three months swap the tapewormer for an all-wormer containing praziquantel – this will ensure your dogs are protected against other important worms.
Don’t allow dogs to eat sheep or goat meat
Home killing of sheep/goats should be carried out in a dog proof enclosure.
Raw sheep or goat meat/offal should not be fed to dogs, instead feed commercial dry dog food (or meat that has been frozen for two weeks or well cooked).
Prevent dogs from scavenging or roaming – when not working tie up dogs or keep in a run or kennel.
Clean up and dispose of dead sheep quickly and effectively (only burning or burial will stop scavenging). This will also stop other species (foxes and dingos) becoming infected.
Remember to think long term in the control of sheep measles. After initiating prevention strategies it is likely you will continue to see sheep measles on abattoir reports for some time as, once infected, cysts are present for life. Control is achieved with time and persistence.
FOR FURTHER INFORMATION:
Contact the Enhanced Abattoir Surveillance (EAS) Program manager Dr Elise Matthews, your local veterinary practitioner, livestock consultant or local PIRSA Animal Health Officer.
FOR ANY SIGNS OF UNUSUAL OR SERIOUS ANIMAL DISEASE, PLEASE CALL THE 24/7 DISEASE WATCH HOTLINE: 1800 675 888