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The Pamphlet Collection of Sir Robert Stout: Volume 29

Scab in Sheep and its Cure

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Scab in Sheep and its Cure.

The present article is a sequel to the one that appeared on "Scab in Sheep" in the April number of the New Zealand Country Journal, and treats of the Cure of Scab; and as in the former article, the information has been obtained from the same source (with the exception of that portion which treats of the Lime and Sulphur Cure), the pamphlet written by Mr. Alexander Bruce, Chief Inspector of Sheep for New South "Wales.

P. B. Boulton.


The Cure of Scab.

1. Its Principles.—It will be gathered from the article on Scab in Sheep, that it is necessary, in order to effect a permanent cure of Scab in Sheep, in the first place that the sheep be dipped and re-dipped in some "curative," i.e., a medicament which will completely destroy both the acari and their eggs; and, in the second place, that the sheep which have been thus thoroughly dressed should either be immediately removed to a clean run, or that such a thorough and lasting "disinfectant," i.e., a preservative against re-infection, should be used with the "curative" as would insure the protection of the sheep from the acari existing on the infected run, for a period beyond that during which the insect could possibly live in any other situation than on the sheep.

In early days the former course was adopted in Australia, as there was then plenty of spare clean ground to which the sheep could be removed on being dressed, and a permanent cure was generally effected.

2. Tobacco and Sulphur Cure.—History.—As, however, this country became so thickly stocked as to render it impracticable to find fresh pasturage for such sheep on their being dressed, the other alternative, the employment of a lasting disinfectant with the curative became necessary. Among other specifics for this purpose, sulphur was tried, but with such fluctuating success that its qualities as a disinfectant of sufficient duration to outlive the insect were for some time very much doubted. It was not until 1854, that Mr. John Rutherford, then of Hopkins Hill, now of Yarra Wonga, Upper Murray, Victoria, by properly apportioning the quantities of tobacco and sulphur (viz:—lib. of each to five gallons of water), and by dipping the sheep twice at an interval of from ten to twenty-one days in a careful and systematic manner, fairly established the character of sulphur as a lasting "disinfectant," while at the same time confirmed the belief in tobacco as a most effective "curative," which, although very destructive to insect life, is comparatively innocuous to that of animals.

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Result in Victoria, South Australia, and New South Wales.—On the Hopkins Hill Station, Mr. Rutherford, with two dressings of these ingredients, then cured over 52,000 sheep, which had been infected for eighteen months; and he also subsequently cured with two dippings the sheep on Mount Fyan's Station, where they were in a most wretched state, and had been scabby for more than three years; and that, too, in both cases, without destroying a single hurdle or yard, or removing any of the sheep from their old runs.

Since then, millions of scabby sheep have been permanently cured in Victoria in the same way; and in South Australia and New South Wales, hundreds of thousands of scabby sheep have also been cleaned with tobacco and sulphur. In fact, this dressing has the credit of having eradicated scab from the flocks of both these latter colonies; and there are good grounds for asserting that had this remedy not been known and used, neither colony would be, as they both are now, almost entirely from the scourge.

3. Tobacco and Sulphur and other Dressings Contrasted.—The particulars of the dressings used in South Australia are not here adducible, but those of New South Wales are, as returned by the different Inspectors, and they speak for themselves.

They are as follows :—Tobacco and Sulphur cured 184,270, failing at first in some few instances through the carelessness or ignorance of the operators, but in the end proving always successful. Of this number about 116,000 had only two dressings—the regular course—about 17,000 had three, about 33,000 had four, and some 18,000 had five or more, owing to mismanagement in their application.

Allen's Specific cured none, but failed in the case of 80,021. Hayes' Specific cured 6,255, and failed with 80,931. Arsenic, and Arsenic and Tobacco (with fresh runs) cured 9,284, and failed with 9,271.

In England, too, and on the Continent of Europe, the faith in tobacco as the best curative for scab is still unchanged, as may be gathered from the following extract from the Scottish Farmer :—Preparations of tobacco have as yet been recognised as the best for the destruction of the scab insect. Professor Gerlach, Director of the Veterinary College, Hanover, accords them the best position for this purpose, and farmers in this country seem to agree on this point. Experiments on a small scale on the efficacy of specifics for the cure of scab have proved thoroughly unreliable, for all these specifics which cured sheep at the trials which took place in Melbourne some years ago, failed completely when used on stations of even a moderate size; and it would seem that they did so principally from the want of a lasting disinfectant in their composition, such as sulphur has proved to be.

Almost everything tried as cures for scab will be effectual on a small scale. Even soft-soap and warm water frequently applied, have cleaned page 163 a scabby sheep. Preparations of corrosive sublimate arsenic, sulphuric acid, and other poisonous ingredients for the cure of scab should be avoided for the following reasons :—1st. They are liable to poison the sheep if administered in the shape of a bath, and their application by hand is impracticable considering the rate of wages and the number of sheep to be dressed. 2nd. To cause them to lose their teeth, and even to hurt their constitutions. 3rd. To bring on sloughing and ulcerations, which frequently carry numbers of them off, and in the case of the arsenical dressing, cold wet weather following the dip is certain to cause a great many deaths In some instances, during the last outbreak of scab in New South Wales, the deaths from dipping with arsenic in winter were from 40 to 50, and in one flock as high as 80 per cent. 4th. To cause great loss in wool. 5th. To occasion painful sores on the hands, and even deaths among the men dressing. And 6th, to be the means, through carelessness on the part of persons using the poison, of causing the deaths of animals, and sometimes even of human beings. Besides, the advocates for the use of any of these poisonous ingredients forget they are only curatives, not disinfectants; and they will find on inquiry that the cures of former days, which they attribute to these medicaments, were only affected through placing the sheep on clean runs immediately after dressing, or perhaps by keeping up such a regular round of spotting and dressing with some of these ingredients, as to continue their effect on the sheep beyond the term of the existence of the acari.

Dipping Apparatus.

As success in dipping will in a measure depend on having everything connected with the apparatus in perfect working order, no false economy should allow of make-shift expedients being resorted to.


It is very important that the yards should be so planned that they are easily worked, and of such a height and strength as will render it impossible for any of the sheep to break away before dipping.

Duration and Heat of Bath.—When the fleece is short, the bath should be administered at a temperature of 120 degrees Fahrenheit in the winter, and at 110 degrees in the summer, at which it should be the endeavour to keep it throughout the dipping (the thermometer being tried every other dip full); and the sheep should be allowed to remain in the dip from 60 to 80 seconds, and as much longer as they can stand it; for with short fleeces they dry almost immediately after being put into the draining yards, and if the bath was not severe both as to temperature and duration, they would stand less chance of being cured than if they were in full fleece or nearly so, whereby they take out and retain" more of the mixture. As the mixture cools, it will be necessary to keep the sheep longer in it, say from one-and-a-half to page 164 two minutes altogether, but in no case should the temperature be allowed to fall below 100 degrees. "When the fleece is long, the heat of the mixture should be maintained at a temperature of from 100 to 110 degrees in the summer, and from 105 to 115 degrees in the winter, and the sheep should be kept in the dip nearly, though not quite, as long as when the fleece is short. These periods are given by way of a guide for the purpose of timeing the process, which ought to be carefully attended to, but it will be for the person in charge to see that while the sheep are thoroughly saturated and kept as long in the dip as they can stand it, none of them are detained till they are in danger of being drowned.

While it only takes 30 seconds to kill the scab insect with the mixture at 90 degrees, it will live for 10 or 12 minutes in the same mixture at 45 to 50 degrees. It will thus be seen how very essential a high temperature is to the success of the dipping, and as a case in point, it may be stated that an owner at a long distance from Sydney, ran short of materials, and effected a thorough cure with half the ordinary strength of ingredients, by keeping the temperature of the bath at fully 130 degrees. There is little doubt, too, if we are to judge by the experience of the process of incubation of eggs by artificial heat, but that the high temperature here given destroys many of the eggs of the insect, which, at the time of the dipping, are still in the skin, and not near maturity. Indeed, if the destruction of the acari and their eggs on the sheep were all that was necessary to a permanent cure, there are good grounds for supposing that this might be effected by the high temperatures sometimes attained in the Turkish bath, without the use of any medicaments.

Second Dipping.—One dipping if carefully and thoroughly performed as directed, is said, in some hands, to have made a cure; but the practice ought always to be to dip twice at an interval of from ten to twenty days to make the matter a certainty; for not only will any sheep, which may have been imperfectly dressed at the first dipping be thus certain of being thoroughly so at the second, but all the acari which were in an embryo state in the skin at the first dipping and thus escaped destruction, would, by the time the second was carried out have reached maturity, and would be destroyed.

Third Dipping.—This may be necessary at times, when any doubt whatever is cast upon the efficacy of the dressing administered. Thus it is most essential, when sheep are exposed to a fall of rain, or allowed to go into water shortly after dressing, and especially so when their fleeces are short.

Lambs Dipped.—Where lambs are dropped about, or shortly after the second dressing given to their infected mothers, they should be properly dipped as soon as they are able to stand the operation, for by running on the infected ground, they would otherwise stand a good chance of becoming diseased.

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Rams Dipped.—As rams are bad swimmers, care should be taken that they are not allowed to leave the dip until they are thoroughly dressed, which their heavy fleeces and twisted horns render somewhat difficult. They should, of course, be put through by themselves, and no more than seven or eight of them should be put into the dip at once, while every part of their heads and necks should be thoroughly saturated.

Dipping Stragglers.—Although it should happen, as it is to be hoped it will, that the two dippings effect a cure, the use of the dip will not then cease, for in or near a district where scab has existed, it ought to be an established rule with the sheep owner, for at least twelve months after the last cure of infection in or near his neighbourhood, that every sheep which has strayed off his run, or has mixed with those belonging to other runs, should on recovery be carefully dipped either once or twice, according to the character of the ground on which it was found, or of the sheep with which it had mixed.

Dressed Sheep.

1. Precautions after Dressing.—Shepherding and Inspection.—While under treatment for scab, sheep should be in the charge of a particularly careful and trustworthy shepherd, but especially so after their course of dressing is completed, and he should receive strict injunctions to watch for and report the least sign of activity in the disease. The owner or superintendent should make a point of seeing the sheep every other day, and he should not only examine every sheep shewing any symptoms of the disease, but he should spend an hour now and then with the shepherd, watching the movements of the sheep as they feed, and he should be increasingly watchful when the weather is favourable to the development of the disease. If ordinary care and watchfulness be displayed by the owner and shepherd, the very first symptom of a re-outbreak will be detected, and another dressing would then make the euro a certainty.

Mode of Examination.—In examining a flock of sheep which have undergone a course of dressing for the purpose of ascertaining whether or not they are cured, every sheep shewing any symptom of the disease should be handled; and after the bare portion of any suspected spot (such as the mark of an old patch of scab) has been carefully examined, the scurf and loose wool should be well cleared away from its outer edges, and the portions of the skin thus exposed should be subjected to the strictest scrutiny, for it is at the edges of the patch that any acari which have escaped destruction by the dressing, are most likely to be found. After that, the fleece should be opened for four or five inches, at right angles to and all round the patch—in the manner already directed—and the skin and roots of the wool along the lines thus exposed should be carefully examined both with the naked eye and the scab glass.

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Keeping Infected Flocks Apart.—The duty next in importance to careful shepherding and regular inspection of sheep which have been dressed, is to see that the infected flocks are neither allowed to come in contact directly or indirectly with clean sheep, nor even with one another. It might sometimes do no harm for two infected flocks to come in contact, but at other times it would, for the one might be perfectly cured and the other not; and thus through the want of a little care, both flocks would again be infected. The infected flocks should be kept strictly apart until thoroughly clean, and the better to enforce this the owner should put a distinguishing brand on each flock when branding them as infected, or rather, he might put the scab brand (S) on the rumps of the sheep of one flock, on the back of another, and on the hips of a third.

Burning Yards.—Although not absolutely essential it is a very wise precaution to burn all brush yards, and the dung which may have accumulated in old yards and camps used by infected sheep; and if practicable, the run where infected sheep have been depastured should also be purged by fire. If these suggestions are not or cannot be followed, the sheep should at any rate be kept away from such places for six or eight months.

2. Successful Dressing.—Symptoms of a Cure of Wet Scab.—If the dressings have been thoroughly effective, the following symptoms will be observable on patches where the attack has been moderately severe. By the time the sheep are to be dipped a second time, and even earlier, there will be little or no rubbing, biting, or scratching, observable in the flock, and the scab will have become dry, while those portions of the skin of the scabby patch which were green when the sheep were dipped will have lost their moistness and appear of a pale dead colour. At a distance of a week from the second dipping the scab will become finer and drier, and the skin although still of an unhealthy colour, will be less harsh and boardy, and thinner and more pliable. At fifteen or twenty days the young wool will begin to shoot up, and, as it does, it perceptibly raises the scab (which has now assumed more the appearance of scurf) from the skin, and the skin will become much healthier in its colour and texture, although still deficient in both respects. At thirty days the young wool will begin to cover the patch, and the scurf will be almost completely cleared off, leaving the skin somewhat white and thick, but perfectly healthy; a slight scratch will at once bring up the proper hue. From that time it is purely a question of growth of wool.

When the attack is a slight one, and the patches small, if the first dressing has been effective, the scab will be quite dead and dry in the course of 12 or 14 days, and the patch will, in many instances, be clear of scab. In the course of a week from the second dressing the patches will be entirely free from scab and scurf, and the skin will have become soft, thin, and of a healthy pink colour, while the young wool will begin to sprout.

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Symptoms of a Cure in Dry Scab.—In the case again of a cure of a spot or patch of dry scab from which the wool had not been denuded when the sheep were dressed, changes, similar to those already described, would take place in the scab and skin, but the old wool would not come off until the young fleece, springing up after the second dressing, forced it, as it were, off the affected spots. In the course of a week or fourteen days after the second dressing, these spots would be noticeable by a rising and slightly ragged or broken appearance of the wool on them, and, by the latter period, a slight new crop of wool would be found on pulling away the raised portion of the old fleece.

3—Unsuccessful Dressing.

Mode of Tracing, Cause of Failure.—If it should unfortunately happen that a course of dressing has been unsuccessful, the owner should not rest satisfied until he discovers the cause of failure. To do this, he will, of course, make the necessary inquiries of the shepherds and hands on the station, and if he cannot in this way arrive at the reason for the outbreak, he should handle and examine every sheep in the flock, when he will be able to see whether any strange sheep have joined with and re-infected it, or whether the disease has re-appeared from the cure being imperfect. If the dressing is at fault, he will, of course, also be able to discover, from the appearance of the spots, whether the failure has occured in the curative or the disinfectant, and to remedy his mistake in the next dressing. Thus, where the dressing has failed through being badly applied, he will meet with the insect, or with green or active scab on some portion of an old patch, most likely at its edge, where the wool though loose has not yet fallen off. In the case of re-infection from insects on the run again, the symptoms will be pencilly, and the scab or insect found, may be at a distance from any old patch or spot, while the symptoms of the attack will of course resemble those of an original outbreak of the disease.

Recapitulation of Causes of Failure in a Cure.

Although nothing is more certain than that the process now detailed is with care, punctuality, and attention, not only a positive cure, but also a lasting disinfectant, it must be continually borne in mind, that if one sheep be omitted or is insufficiently dressed, the greater part of the labour will be lost.

It is imperative, therefore, that the person superintending the operation should be keenly alive to the responsibility devolving upon him. He will have to look after everything, and everybody, and he must see that the dressings are correctly and carefully made up and applied to every doubtful and infected sheep on the run. It is utterly needless for careless sheepowners or superintendents to attempt to cure sheep of scab.

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To those, however, who will take the necessary pains, but who are as yet little acquainted with the process of dipping, it may be useful to mention briefly the chief causes of the numerous failures which have occurred in the attempts made to cure sheep with tobacco and sulphur. They may be enumerated as follows:—
1.Leaving sheep, especially crawlers, which are unable to follow the flock to the dip out on the run, and thus omitting to dress them, or neglecting to destroy the carcases of infected sheep which may have died on the run. Before dipping is commenced every crawler should be killed and burned, and a careful account should be taken some three or four times at least, immediately before dipping, of all sheep on the run, to ascertain their actual number beyond the possibility of a doubt, with which the number dipped must be made to tally exactly, while a thorough search should be made for dead sheep, which should be burned where found.
2.Using Inferior Tobacco.—There wall be little or no difficulty with respect to the quality of imported manufactured or leaf tobacco, and the colonial leaf must be well sweated and tough in texture.
3.Omitting to keep the mixture at the proper strength and heat.—The overseer until he can thoroughly depend on the man at the boilers, must see personally that the proper quantities of tobacco and sulphur are weighed out, and the replenishing of the dips and heat of the mixture are correctly attended to.
4.Neglecting to form a "diseased" flock of those sheep which are very badly scabbed.
5.Allowing sheep to pass from the dip before the mixture has been thoroughly applied to them, or before it has had time to do its work, especially as it becomes cool. The overseer ought to time the operation, watch in hand, and the heat should be frequently tested with the thermometer.
6.Neglecting to dip within the proper time.
7.Being in too great a hurry to draft, or class sheep which although apparently clean, have not served their proper probation, and taking sheep from one flock and putting them in another. This is very imprudent, as it may happen that though the cure is perfect in one flock it is not in the other, and thus both lots would be again contaminated.

Lime and Sulphur.

Of late years the ingredients in general use in New Zealand for the cure of scab have been lime and sulphur; and this cure commends itself to the notice of sheep owners, not only on account of its cheapness, but also from the success which has attended its use where due attention has been paid to the strength and quality of the mixture.

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Mixing the Ingredients.

It is as well to crush the lime and sulphur with a heavy roller, and mix them well together; then put the whole through a fine sieve, which takes out all the small lumps, making the incorporation perfect, which latter is important.

Preparing the Mixture.

Thoroughly mix five cwt. of flour of sulphur and three cwt. of slacked lime; empty it into 1,400 gallons of boiling water, which, keep on the boil, stirring well from the bottom for twenty minutes, when it is ready for use. Keep the dip up to a temperature of 115, or 120 if the sheep are very scabby, and let them remain for two minutes in it, during which time put their heads under twice. Repeat the operation a second time within fourteen days.