The following article is by Dr Bruce Watt of Tablelands LHPA (central tablelands area of NSW) and is published here with permission.
(Hyperlinks added by blog owner).
ABATTOIR MONITORING NOW REPORTING ON A RANGE OF SHEEP DISEASES
In the last few weeks, a number of sheep producers have phoned to ask me about bladder worm (Cysticercus tenuicollis) in sheep. The reason for the sudden interest in this parasite is that these producers have recently consigned sheep for slaughter. Abattoir meat inspectors have detected bladder worm in the carcase. These finding have now been reported back to producers via the National Sheep Health Monitoring Program.
The program is being piloted in the Tablelands LHPA. Meat inspectors are reporting on a wide range of conditions from hydatids, sheep measles, liver fluke, OJD (ovine Johnes disease) and pneumonia to grass seeds, dog bites and bruising.
Dr Ian Links, Biosecurity Special Projects Officer who works for an alliance between Industry and Investment NSW and CSU Wagga then collates and distributes the reports to producers.
Bladder worm is a tapeworm cyst. It is quite common and is sometimes mistaken for hydatids. However as the name suggests the cysts look like a bladder filled with clear fluid. It also contains a white spot, the tapeworm head. These cysts occur around the liver while the adult tapeworm lives in dogs.
I needed to know more before answering the questions these producers put to me so I turned to Dr David Jenkins now also at CSU. I have known David for nearly thirty years and have always enjoyed his infectious enthusiasm. He is also a world expert on tapeworms.
David reminded me that dogs acquire the tapeworm when they are fed sheep offal that contains the cysts. The mature tapeworms inside dogs produce segments every day or two and these segments contain a massive number of eggs. These eggs are also tough, surviving for a year or two.
Sheep consume the eggs when they eat contaminated pasture. After the eggs hatch inside the sheep, the little worms burrow through the gut wall and migrate through the liver causing damage along the way. If sheep eat sufficient larval their health and productivity can be affected.
The larvae then develop to form a cyst on the liver while they wait for the opportunity to become a dog’s breakfast and complete their life cycle.
Bladder worms are harmless to dogs and people but their presence indicates that tapeworms are maturing in home or visiting dogs. This means that these dogs could also be carrying the much more serious hydatid tapeworm or the tapeworm that cause sheep measles.
If you have lived in rural NSW for a generation or two you will almost certainly know someone who has suffered the consequences of hydatid cysts. As you will know, they are dangerous and can be fatal.
Sheep measles causes small white cysts through the meat leading to carcase condemnation. Fortunately, it is not a health risk to consumers but the rice grain sized lumps in their roast do not impress them. You will also not be impressed when the abattoir reports to you that they have condemned a proportion of your consignment.
Therefore, if your get a report of bladder worms in your sheep consignment take it as a gentle reminder that you need to control tapeworms in your dogs. You can do this by dosing them every 4-6 weeks (using a product containing praziquantel) and by ensuring that your dogs and those of your visitors are not fed fresh sheep meat (unless it has been frozen for 14days) or offal.
Remember that dogs belonging to casual farm workers are a source of tapeworms. It is recommended that you ask that they be tied up for 3 days after dosing and their droppings collected and disposed of safely.
The National Sheep Health Monitoring Program has the potential to deliver valuable information both to individual farmers and to the region. I am sure I will be reporting more of its findings to you in the future. I would like to commend The Sheepmeat Council of Australia, WoolProducers Australia and Industry and Investment for supporting this initiative.
For further information on larval cestodes of sheep and other animals see:
The following Primefacts at the NSW DII website:
The sheep measles Primefact also has a table with a summary of ‘cysts of larval cestodes (tapeworms) of sheep and cattle’.
Also see the WormBoss website: www.wool.com/wormboss (The old URL, http://www.wormboss.com.au , will redirect to the new location).
While you are there, spend a few minutes doing the WormBoss on-line Survey. 🙂