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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.
Whip Worm (Trichuris ovis) of Sheep
E. A. FARLEIGH, B.V.Sc., Veterinary Inspector, Glen Innes
During the drought on the Northern Tablelands in 1965 it was noted that there appeared to be a significant increase in whip worm infestation in sheep that were in poor condition.
It is normally accepted by parasitologists that, although whip worms can be found in many sheep, they do not cause any concern and no definite pathological change can be specifically attributed to their presence.
The first indication that this statement might not be correct was during post-mortem examinations carried out on merino weaners, early in July, 1965, on a property 15 miles west of Glen Innes. These sheep had been totally hand fed on wheat for some months and evidence of scouring and loss of condition had been noted and deaths were increasing each week.
Six autopsies were carried out and the only parasite present was whip worm. No attempt was made to count the worms, which extended from the end of the caecum into the coiled portion of the colon. It was estimated that the number of worms in each caecum would be many hundreds.
All the sheep were dosed with “Mintic" and immediately improvement was noted, scouring ceased and no further deaths took place.
Six weeks later a four-tooth merino wether was examined post-mortem on a property in the Ben Lomond area and an equally heavy whip worm infestation was seen in this animal and no other internal parasites were found. This sheep, from a flock being fed on wheat, had been losing condition and scouring and had been removed to a hospital paddock where a green pick was available and it was fed on hay. It was unable to stand after being in the paddock for a few days and was becoming progressively weaker. No wheat could be found in the rumen and it was considered that the animal had not been eating grain.
The same day on an adjoining property post-mortem examinations were carried out on two poor conditioned ewes, which were four to five weeks off lambing and had been too weak to stand for some days. One ewe was still eating hay, but the other would not eat.
Again a very heavy whip worm infestation was seen in both animals extending throughout the length of the caecum and into the colon. In one case 10 to 12 nodule worms were also seen. Both ewes were scouring badly.
These sheep had been hand fed on wheat for two weeks and also on the day in question nuts were added to the diet of the flock.
Eight days later a further visit was paid to this property. One autopsy was carried out on a recently dead ewe, which was not in lamb. It had been scouring and again a massive infestation of whip worms were seen. Three poor ewes showing evidence of scouring were taken alive to the Veterinary Laboratory at Armidale. On post-mortem examination two showed a heavy whip worm burden and one only a very light burden. An attempt was made to make a total worm count, but this could not be done owing to the clumping nature of the worm after removal from the caecum. Other worms present in one sheep were two hundred adult and six hundred immature Ostertagia in the abomasum. and in the other four hundred adult and five hundred immature Haemonchus. There was no evidence of any inflammation in the caecum or colon, which could be attributed to the presence of the whip worms.
The significance of a heavy whip worm infestation in sheep in poor condition and being hand fed on grain is not known, but it is felt that this worm may assume some pathological importance under periods of stress.
A feature noted in sheep with a high build up of whip worms is that the worm is situated not only in the blind end of the caecum, but also it is attached throughout the whole length of the caecum and into the colon.