Art. XXXVIII.—On Pseudo-scab and Lung-worm in Sheep.
[Read before the Wellington Philosophical Society, 6th August, 1881.]
Pseudo-scab in sheep.
A disease in sheep resembling Acari Scab, having recently; attracted attention among flock-owners, several pieces of affected skin were forwarded by the Sheep Department to the Museum for examination and report, but with no definite results, in consequence of the disease in every case having reached its crisis and the wool having again begun to grow, and only in one case was it clear that the skin had been burrowed by worms.
The conclusions arrived at in lung-worm disease, regarding the life-history of the lung-worm (Strongylus filaria), are clearly applicable in the present case, and it is also highly probable that the same species or an allied one produces this eruption on the sheep, the eruption disappearing in autumn, after which the sheep regain their usual health. The conditions most favourable to the selection of the skin as a nidus, are wet seasons, when the sheep are in a continually soaking condition from rain; such weather is also favourable to the movements of the young worms when in search of a host.
It is doubtful whether the worms in every case burrow into the skin, as no doubt the clotted secretions of yolk at the base of the wool offer sufficient shelter in many cases; it is certain, however, that a scab is produced in every case where the worms have selected the body as a nidus, and their leaving in autumn is coincident with the departure of the lung-worm.
Positive proof of the species infesting the skin can only be ascertained by those having opportunities of searching for them at the proper time, when this pseudo-scab is prevalent.
The lung-worm in sheep.
The result of an examination of a portion of a sheep's lung forwarded by the Stock Department is as follows:—The sheep was depastured at Marton and was killed in June last. Near the opening of the bronchial tube was found a contorted heap of filiform white worms, which, on examination, proved to be a species of Strongylus. All the specimens examined of this travelling detachment, were found to be packed with eggs, each egg showing under the microscope a coiled embryo within, in an advanced stage of development; a large portion of the lung structure was found to be perfectly healthy, and evidently had not been visited by the worm, but in the remaining portion some worms were found which proved under the microscope to be nearly filled with eggs, none of which, however, showed any traces of an embryo, thus no doubt explaining their delay in moving with the others; male worms were also found here. This portion of the lung proved to be in a diseased state, being flabby and white, the worms having evidently burrowed through its body and formed a lodgment there till they should arrive at their normal size and become fertile with ova. It appears that they remain in the lung till the embryos reach the mature stage of bursting their envelopes, when the parent worms commence to evacuate their temporary abode and move towards the damp ground, where they find the conditions best adapted for the first stage of life of the young worms, and where the parents no doubt die.
It is at this travelling stage that the worms become most dangerous to their host, in proportion to their numbers, filling the air passages of the lungs and nostrils, and often when numerous in weak sheep or lambs causing suffocation. The life-history of this nematode clearly shows that it only occupies the lungs of sheep for a few weeks during summer; leaving the ground in spring while yet in an immature condition and scarcely visible to the unassisted eye, and crawling up the nostrils of the sheep, they reach the lungs without causing much annoyance. The period of escape by the same track in autumn, after they have reached their mature condition and become fertile with embryotic ova, may extend over several days, during which time the sheep labour under great annoyance, and if the worms are numerous are in much danger of suffocation; as they advance towards the nostrils in contorted balls and fill up the air passages, if not speedily expelled the sheep must die. From what has been said it is shown that the maturity of the embryo occurs in some worms earlier than in others, thus lengthening the period of annoyance although diminishing the danger of suffocation, as the worms are not all travelling at one time.
Preventative measures with this disease should always be tried in preference to what may be termed a cure, for it is only when the worms are leaving instinctively that any cure is ever tried, and it were better to assist their escape by cleaning out the nostrils of the sheep than killing them in the air passages of the lungs with the fumes of burning sulphur
Either prevention of access of the worm to the sheep in spring, by their removal to dry ground—or keeping rock-salt in places where the sheep can have access to it, more especially when the young nematode has newly reached the lungs and is of a microscopic size—should be adopted.
When the young worm finds a nidus on the back, and the wool shows the first symptoms of raggedness, an application of a mixture of soft soap in water with a little turpentine or kerosene, if distributed in the opened wool with a groove-corked bottle, would speedily check the evil.
Extracts from Reports of Sheep Inspectors and Notes thereon.
Mr. Foster in a report to the Stock Department describes very correctly; the disease in sheep caused by worms in the lungs; but the proper time for administering remedies is not stated, and any treatment which would kill the worms after they have reached an advanced stage of development is more likely to kill the sheep; every means should be used to get the worms out of the nostrils and prevent suffocation of the sheep. It is very probable that sulphur fumes might prove beneficial if applied when the worms are of a microscopic size, on their earliest arrival from the wet ground.
Mr. Boyes seems to be on the right track with the sulphur fumes, he says he is sure it will cure the bronchial disease “in its earlier stage,” and he means to use it as a preventative; perhaps he expects too much in that as sulphur fumes are not likely to do much damage to worms before their arrival. Why not put soluble sulphur in the blood through the stomach?
Mr. Reginald Foster points out the main feature of the whole subject:
“Most stock-owners wean their lambs on their best feed, which in summer is usually on the moist low-lying land where these parasites or rather their ova exist. Lambing paddocks should be virgin pasture.”
Sheep Inspector Simpson, Marton District, reports as follows: “I forward by mail to-day a package containing portion of a sheep's lung showing a number of worms in its tubes, perhaps you may be able to obtain reliable information if this is the cause of the heavy losses, chiefly in hoggets, for several years past.
“The first symptom is a severe cough, afterwards followed by scouring, which invariably terminates in death. I have very little doubt but the worm is the cause of the cough, and the scouring is an after consequence.”
Mr. Reginald Foster, of Amberley, writes to the Christchurch papers in July last, in reference to a mortality among sheep in some districts of Canterbury, supposed to have been caused by worms. He says: “On Friday last, at the farm of Mr. James Guild, of Ohoka, I examined some hoggets which had apparently died from scour. I found that the lungs were in a highly diseased state, and opening the bronchial tubes I discovered several white thread-like worms about one inch in length. I also found a considerable number of these parasites in the air passages of the lungs. With the exception of a little inflammation in the intestines, caused no doubt by the diarrhœa from which all these hoggets had suffered, the rest of the internal organs were perfectly healthy. Mr. Guild has recently lost a considerable number of hoggets, and there is little doubt that these worms were the cause of their death. So far as I can learn, this disease, well known in England, has not as yet been noticed in New Zealand, but I think it is highly probable that it has been one of the causes of the heavy mortality in young stock, especially in hoggets and calves, from which stock-owners have suffered for several seasons past. The remedial treatment recommended is turpentine, in doses of a quarter of an ounce, given in oil. A simple and more direct remedy is to make the sheep inhale fumes of sulphur in a shed. In advanced cases, where diarrhœa has set in, some medicine to act on the stomach would also be necessary.”
The remarks of Inspector Reginald Foster, in the concluding part of his report are worthy of notice.
“I think that future investigations should be directed towards noticing the earliest stages of the disease, by watching the young stock on farms known to be infected, at what rate the disease progresses, so as to form an opinion as to when is the best time to use remedial measures. Several breeders of stock who have taken some trouble to investigate this disease agree with me, that when the cough is bad and is accompanied by diarrhœa the malady is in too advanced a stage to hope much from remedial measures. So for as my knowledge of the bronchial disease goes at present, I am strongly of the opinion that breeders of stock in low-lying districts, to which the disease appears to be almost entirely confined, should put their weaners through a course of inhalation of the fumes of sulphur about the month of April; this remedy is known to be effectual and is very inexpensive, two men could put 400 or 500 hoggets through in half a day.”
Mr. Charles C. Boyes, in writing to Mr. R. Foster, Amberley, says: “Since writing you I am glad to say my sheep are fast recovering, and I have only one death to record. I have persevered in the sulphur treatment, in which I have great faith, and I am now quite certain that it will cure the bronchial disease in its earlier stage. I tried the oil and turpentine in a few cases,
but I fear the sheep were too far gone for any remedy to have effect. In each of these latter cases I found on opening the sheep that the worms had penetrated the lungs, and when this has occurred I am afraid there is no cure. I have made the infected sheep inhale sulphur four times at intervals of three days, and the flock seem now quite recovered, in good heart and feeding well. The sulphur inhalation is the cheapest and speed iest cure, and I am much indebted to you for your suggestion of it; in future I intend putting the sheep through a course of this treatment at the end of each autumn as a preventative, as I have noticed that this is the season when the disease always shows itself first.
Mr. Reginald Foster, writing to the Stock Department, says:—“We must look rather to preventive means. In this, as in the case of most diseases, I think there must be some predisposition to contract disease, and this is most likely to occur soon after weaning, when those lambs Tyhich had not weaned themselves, being suddenly deprived of their natural food, are for a time debilitated, and would therefore be the more susceptible to disease.
“Most stock-owners wean their lambs on their best feed, which in summer is usually on the moist low-lying land, where these parasites or rather their ova, exist. None but adult stock which are able to resist the attacks of the bronchial worms should be put on rich swampy pastures. Lambing paddocks should if possible be virgin pasture, or should have been saved some time for the purpose, and the lambs should always have access to rock-salt, which is the best known preventative for worms If all kinds The simplest remedies recommended are a dessert-spoonful of turpentine to two of linseed oil, given every other day, about three or four doses; or the sheep should be placed in a close shed and made to inhale the fumes of sulphur. This may be done by sprinkling sulphur on a pan of live coals.
“These remedies have been tried in two or three instances here, but I have not yet heard with what result. I think they would only be effectual in the very earliest stages.”
Extract from Report of the Commissioner of Agriculture, Ohio.
“We have no knowledge of the cause of the lung-worm-a name given for the want of a bettery perhaps. It affects young sheep in a greater degree and to a greater extent than matured animals. The worm is a small white one, and is found in considerable numbers in the lungs, or in tubes connecting the windpipe with the lungs. The symptoms are weakness, failure to eat, loss of flesh, and a cough. This disease is but little understood by the wool-grower.
“Stricana or Strichnia is perhaps a very incorrect name for the disease I wish to describe. It is caused by a very small worm, so minute, indeed, that it cannot be seen without the aid of a magnifying-glass. It is believed
to. cause the sheep to pick or bite the wool from its sides, flank, and other parts, until the fleece becomes more or less ragged and wasted. The skin becomes rough, and shows, symptoms of disease. It is not contagious, but attacks sheep of all ages. It is more damaging in flocks that have been closely bred ‘ in and in ’ for many years; indeed this is the case with most diseases. As both a preventative and cure, wood and cob ashes with salt are used, with partial success.”