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This article was published in 1966
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Field Observations on Moniezia expansa Infestations in Sheep
G. CHARLES, B.V.Sc., Veterinary Inspector, Forbes
Over the years little importance has been attached to the presence of Moniezia species in sheep, but it would now appear that we may have to recast our thoughts on this subject in view of field experiences covering not only weaners in good condition on good feed but also poor weaners under drought conditions. Admittedly there is no controlled experimental work to support this contention but observations over the past five years in the field do appear to indicate that the presence of tapeworms has a definite bearing on the well-being of young sheep, especially lambs and weaners.
In prime lambs and weaners dying from entero-toxaemia, one frequently finds heavy infestations of tapeworms and these infestations are often of such a magnitude as to impede the flow of ingesta. Do these infestations interfere with the digestion of starch or do they cause irritation of the bowel wall thus in either case creating a suitable environment for the growth of Clostridium perfringens? The presence of tapeworm infestations may be purely coincidental but observations made in this district would appear to indicate that losses from entero-toxaemia are higher in flocks infested with tapeworms than in those free from these parasites.
Prime lambs inoculated against entero-toxaemia appear to tolerate a light to moderate infestation without obvious ill-effects. On the other hand forward lambs carrying a heavy infestation have been seen to lose their bloom and develop a scour despite drenching with thiabendazole and access to good pasture. Following a request from the owner, examination revealed the presence of tapeworm segments in the droppings and the lambs were drenched with a phenothiazine-lead arsenate mixture. Within seven days there was a noticeable improvement and the lambs were sold to a butcher four weeks after drenching.
This is just one of a number of similar cases seen over the past five years.
During the recent drought a number of mobs of poor weaners were travelling the stock routes in this district in search of feed, which was limited and scarcely suitable for weaners. Several such mobs developed a scour, lost condition and were unable to travel. The owners drenched them with thiabendazole but with no beneficial result. Assistance was then sought and the condition was diagnosed as a heavy tapeworm infestation, no other internal parasites being found in stained sections of bowel or scrapings. One owner, with a view to reducing expenditure, drenched with a proprietary phenothiazine-lead arsenate mixture, only those weaners showing a scour. These treated weaners showed a marked improvement over the next seven days, whereas the untreated ones, on the same feed, slipped back and commenced scouring with some deaths. At this stage all the weaners were treated, after which deaths and scouring ceased. Ten days after drenching, the weaners were improving in condition and were capable of travelling a short daily stage.
These drought affected weaners were possibly the best example of the ill effects of tapeworms as they were free of other internal parasites and were able to improve in condition, even on poor feed, once the tapeworms were removed. Again, the evidence is only circumstantial and based on field observations, but there would appear to be sufficient basis to justify at least some change in our attitude to tapeworm infestation in sheep.