Chapter II: Phthiriasis (1)

The term phthiriasis is applied to infestation of the skin with lice.

=Causation.= These diseases are due to the presence of various parasites which live by destroying the epidermic scales, or by piercing the superficial layers of the skin. They are of a greyish-yellow colour, and belong to the genera _Hæmatopinus_ and _Trichodectes_.

The _Hæmatopinus_ forms have pointed heads, and are equipped for penetrating the skin by suction. The _Trichodectes_ have a large flat head constructed for masticating.

The ox harbours two forms of _Hæmatopinus_ and one of _Trichodectes_, the _Hæmatopinus eurysternus_ and _tenuirostrus_, and the _Trichodectes scalaris_.

The sheep suffers from _Trichodectes sphærocephalus_ and a _Melophagus_, the goat from the _Hæmatopinus stenops_ and the _Trichodectes climax_, and the pig from the _Hæmatopinus urius_.

=The symptoms= are, with trifling variations, the same in all domestic animals, the principal being rubbing and itching. The animals scratch, bite and attempt to rub against hard objects, even abrading the skin when this is thin and the irritation is severe.

The parasites may, however, remain localised, and it rarely happens that they are present in any considerable number in all parts of the body.

In the ox they are principally found in the depression at the back of the base of the horns, and in the upper margin of the neck and the back. In the absence of treatment phthiriasis may become generalised over the entire surface of the body.

The trichodectes and the melophagus of the sheep choose similar points, but when the wool is long they may be found nearly all over the body.

In the pig the hæmatopinus is found on the neck, in the region of the poll, about the armpits, and round the eyes and ears.

These parasites, whose powers of increase are astonishing, keep the patients in a continual state of irritation, causing them to lose condition and, in the absence of treatment, to die of exhaustion.

=The diagnosis= is very easy, the parasites being visible to the naked eye.

=The prognosis= is not grave unless the condition affects a large number of animals in herds. In young animals the prognosis is much graver, for the little creatures rapidly become anæmic and die in a state of exhaustion.

=Treatment.= When the byre, fold, or piggery is infested the first point is to remove the animals and thoroughly disinfect and cleanse all parts.

After the manure has been cleared out, the walls, mangers, racks, etc., are washed with boiling water, or, better still, potash solution, and disinfected first with vaporised sulphurous acid, then, if necessary, with a washing of caustic lime.

The patients are afterwards clipped, washed with soft soap and dressed with anti-parasitic solutions, such as 1 per cent. tobacco juice, or a mixture of equal parts of benzine and oil or benzine and petroleum, etc., which give excellent results.

A 3 per cent. creolin solution is also a very active anti-parasitic and very easy to use.

All these solutions, however, are more or less poisonous and need to be used with caution, weak solutions only being used at first, particularly in the case of animals, such as oxen, which are given to licking themselves.

SCABIES—SCAB—MANGE.

The term scabies is given to a group of diseases affecting man and all domestic animals. These diseases are produced by two classes of parasites, viz., sarcoptinæ, which live within the epidermis or on the surface of the skin, and demodectes (_sing._ demodex), which penetrate into the sebaceous glands and hair follicles.

Scabies, though known from the earliest times, has long been confounded with constitutional diseases characterised by cutaneous eruptions. The symptoms shown were formerly regarded as due to the elimination of “humours” which the organism was casting off, for which reason scabies was even treated with internal medicines.

At the present time the cause of the disease is perfectly well understood, as well as the mode of development of the different parasites. The rate at which these parasites develop is almost incredible, a fact which explains the highly contagious character of the disease.

Each species of animal may present several varieties of scabies, caused by different parasites, such as sarcoptes, psoroptes, chorioptes, demodectes, etc.

SCABIES IN SHEEP.

Scabies in sheep usually assumes one of three forms—sarcoptic, psoroptic, or chorioptic scabies. Follicular, or demodectic, mange affects the eyelids, and is very rare. It is produced by the _Demodex folliculorum_ var. _ovis_.

SARCOPTIC SCABIES

This scabies has long been recognised as affecting more especially the head, muzzle, etc. It was mentioned as long ago as the fourteenth century by Jehan de Brie, but, until Delafond’s time, no one recognised that it was caused by an acarus. In 1858 Delafond discovered the parasite in Piedmont sheep.

=Causation.= Formerly, writers on the subject and shepherds attributed this disease to the wounds and excoriations which sheep receive in passing through brambles, holly, etc., or in rubbing against their racks. The true cause of the disease is the presence under the skin of the _Sarcoptes scabiei_ var. _ovis_, which passes from sheep to sheep by direct contact. The animals attempt to rub against everything about them, even against their neighbours. These parasites can be transferred from the goat to the sheep, and _vice versâ_.

Walraff, Roloff, Delafond, Gerlach and Railliet have described cases of infection in man, but the disease is rarely more than of a temporary character.

=Symptoms.= This form of scabies affects the head and the parts free from wool.

At first the parasites invade the upper lip and the tissues about the nostrils, sometimes, but more rarely, the eyes and ears. They cause the formation of vesicular papules, accompanied by violent itching. The animal, in rubbing itself, excoriates these papules, which discharge a fluid and soon become covered with yellowish-brown crusts.

The disease afterwards invades the face, forehead, jaws, and entire head. The skin becomes wrinkled and the brownish crusts thicker and more abundant. These are fissured and bleeding, and they give the face the appearance of one vast sore.

The parasite rarely attacks the region of the elbow, the belly, or the inside of the thigh. The disease never advances in parts covered by wool, although in breeds of sheep with thick wool, such as are found in Algeria and Tunis, the sarcoptic form of scabies may become generalised and attack the entire body. The extremities of the limbs, however, are usually attacked after all the head has become involved.

Throughout the course of the disease the patients scratch and rub themselves, thus tearing off the crusts and causing bleeding and the formation of new crusts of a blackish hue. This form of scabies about the head may become complicated with conjunctivitis, the inflammation extending from the extremity of the eyelids to the conjunctiva. This arises from the fact that the membrane is frequently injured by the animal rubbing the parts. Conjunctivitis may be so intense as to lead to purulent ophthalmia and the loss of the eye.

=Diagnosis.= Sarcoptic mange in sheep cannot be mistaken for any other disease on account of its localisation.

=Prognosis.= The disease is not very dangerous, for it is easy to treat, though if left to itself it might in time become fatal.

=Treatment.= Preventive treatment consists in isolating diseased animals, cleansing and disinfecting the folds, and preventing the introduction of diseased animals into healthy flocks.

=Curative treatment.= When the disease is detected at an early stage anti-psoroptic remedies may be directly employed.

If, however, it is of old standing, the crusts must first be softened and removed by the use of fatty substances, such as vaseline or oil, before any curative treatment can be undertaken.

The crusts can be removed in from twenty-four to forty-eight hours by vigorous washing with soft soap and the application of anti-parasitic solutions. The omission to wash the parts causes drugs to lose much of their efficacy.

Helmerich’s ointment, oil of cade, mixtures of oil, benzine and petroleum, and 3 per cent. to 4 per cent. of tobacco juice, are the commonest and most efficacious applications.

A non-poisonous ointment may be made by taking 4 ounces of oil of turpentine, 6 ounces of flowers of sulphur, and 1 lb. of lard. Mix the ingredients at a gentle heat, and rub in well with the hands or with a brush, at the same time breaking the crusts. The simple sulphur ointment may be made of one part of sulphur and four parts of lard; one fourth part of mercurial ointment may be added. Few remedies are so useful as sulphur iodide, and it may well be given a trial on head scab.

In most countries this disease has been made the subject of special legislation.

PSOROPTIC MANGE—SHEEP SCAB.

This is probably the gravest form of mange. It was described by Cato the Censor in 160 B.C., by Virgil, Juvenal, Celsius, Columella, Pliny, Vegetius, etc. In 1787 Abildgaard first showed that psoroptic mange in sheep could be cured by simple external remedies, without internal medications. In 1809 Walz described the causes, nature, seat, and treatment of the disease.

Since then, the parasitic, contagious nature of mange or scabies has been more and more clearly recognised.

=Causation.= Experience and observation have long shown that the only cause is the presence of the _Psoroptes communis_ (_ovis_). This disease is much more contagious than that just described. Psoroptic mange or scabies exclusively affects those portions of the body covered by the wool, and may for a long time remain unrecognised.

The parasite is visible to the naked eye, though most inspectors employ the microscope. The adult female is about ¹⁄₄₀ of an inch long and ¹⁄₆₀ of an inch broad; the male is ¹⁄₅₀ of an inch long and ¹⁄₈₀ of an inch broad. The mites are discovered more easily on a dark background, and if a portion of the wool and crusts is placed on black paper and exposed to the sun for a few minutes the parasites will generally be seen crawling about on the paper.

The disease is transmitted directly or indirectly by contact from diseased to healthy animals in the folds, fields, or sheep runs. One diseased sheep may contaminate an entire flock. The disease is extremely contagious, and may appear even within a week after exposure.

The parasites have exceptional vitality. It is generally stated that, kept at a moderate temperature on portions of scab, the adults may live from four to twenty days, but they will occasionally live much longer; cases are on record where they have lived three, four, or even six weeks when separated from sheep; if the atmosphere is dry they will generally die in about fifteen days; but death is often only apparent, for the mites may sometimes be revived by warmth and moisture even after six or eight weeks; the fecundated females are especially tenacious of life.

Experience has shown that in some cases apparently healthy sheep have become infected in places where no sheep have been kept for four, eight, twelve, or even twenty-four months. The conditions underlying this infection are not thoroughly understood. Possibly some of the eggs have retained their vitality a long time and then hatched out; possibly the vitality of the fecundated female has also played a _rôle_; while it is not at all improbable that an entirely new infection has accidentally been introduced by birds or other animals. Certain authors of high standing scout the idea that birds can introduce an infection of scab, but there is no reason why birds should not do this, and there are some reasons for believing that they do. It has been noticed on the Experiment Station of the United States Bureau of Agriculture, for instance, that crows delight in perching on the backs of scabby sheep and picking at the scab; while so doing it is only natural that small tags of wool would adhere to their feet, and thus scatter scab.

Delafond’s experiments show that psoroptic mange is most troublesome amongst thin, ill-nourished, weakly animals, whilst robust sheep in good condition may be cured simply by attention to cleanliness and abundant feeding.

In America this disease causes extremely heavy pecuniary loss, second only in importance to that produced by hog cholera. It has also interfered very seriously with the export of American sheep.

=The course= of the disease is affected by the time of year and surrounding conditions. In autumn and winter, when sheep are in continual contact in a moist, warm atmosphere within the folds, the disease makes rapid progress. Young, weak, closely-inbred animals, and those with long, coarse wool, most quickly succumb. Unhealthy surroundings, damp, and bad ventilation favour the disease. Pure or mixed bred merino sheep suffer severely. In summer the animals are generally shorn and live in the open, and the disease then usually diminishes or may even be arrested.

A study of the life history of the scab parasite is necessary in order to determine several important points of practical value, such as the proper time for the second dipping, etc.

The female mite lays about fifteen to twenty-four eggs on the skin, or fastened to the wool near the skin; a six-legged larva is hatched; these larvæ cast their skin and become mature; the mites pair and the females lay their eggs, after which they die. The exact number of days required for each stage varies somewhat, according to the writings of different authors, a fact which is probably to be explained by individual variation, and by the conditions under which the observations and experiments were made. Thus Gerlach, in his well-known work (1857) estimates about fourteen to fifteen days as the period required for a generation of mites from the time of pairing to the maturity of the next generation. He divides this time as follows: Under ordinary conditions the eggs hatch in three to four days, although two authors allow ten to eleven days for the egg stage; three or four days after birth the six-legged larvæ moult and the fourth pair of legs appears; this fourth pair is always present when the mites are two-thirds the size of the adults; when seven to eight days old the mites are mature and ready to pair; several (three or four) days are allowed for pairing; another generation of eggs may be laid fourteen to fifteen days after the laying of the first generation of eggs. Without going into all of the other observations on these points, it may be remarked that the eggs may not hatch for six or seven days; the six-legged larvæ may moult when three to four days old, and become mature; after pairing, a second moult takes place, lasting four to five days; a third moult follows immediately, then eggs are laid and the adults die; in some cases there is a fourth moult, but apparently without any further production of eggs. Accepting Gerlach’s estimate of fifteen days as an average for each generation of ten females and five males, in three months time the sixth generation would appear and consist of about 1,000,000 females and 500,000 males.

Several practical lessons are to be drawn from these figures: Firstly, it is seen that the parasites increase very rapidly, so that if scab is discovered in a flock, the diseased sheep should immediately be isolated; secondly, if new sheep are placed in a flock, they should either first be dipped, as a precautionary measure, or they should at least be kept separate for several weeks to see whether scab develops; thirdly, since the chances for infection are very great, the entire flock should be treated, even in case scab is found only in one or two animals; fourthly, as dipping is not certain to kill the eggs, the sheep should be dipped a second time, the time being selected between the moment of the hatching of eggs and the moment the next generation of eggs is laid. As eggs may hatch between three and seven, possibly ten or eleven days, and as fourteen to fifteen days are required for the entire cycle, the second dipping should take place after the seventh day, but before the fourteenth day; allowing for individual variation and variation of conditions, the tenth, eleventh, or twelfth day will be the best time to repeat the dipping.

=Symptoms.= Psoroptic mange attacks the parts covered with wool, so that attention is only drawn to the disease by some slight injury to the fleece, which becomes rough, matted, brittle, and liable to fall.

Scabies commences with intense pruritus. The animals scratch and bite themselves, and tear away the fleece. These symptoms become aggravated when the animals are hot, as, for instance, when travelling. If the sheep have travelled through mud, the fleece becomes matted on the neck, behind the shoulders, and at all points where they are able to scratch themselves with the hind limbs.

When a scabby sheep is touched at a diseased point, the animal shows pleasure by nibbling and moving the head up and down.

At an early stage, if the fleece is divided and the skin examined, little papules may be discovered somewhat less in size than a lentil. They are of a yellowish colour, and are distinctly visible against the reddish colour of the skin. These papules are due to the attacks of the psoroptes.

They soon become more numerous and even confluent, break and discharge, become converted into pustules, and cause the formation of crusts. In a few days the diseased points are covered with a squamous, yellowish, sticky covering, under which the psoroptes lie hidden and which affords them nourishment.

The crusts steadily grow thicker and lift the individual fibres of wool, tearing them from their follicles, so that patches of skin become bare. The patches thus formed increase in diameter, for the acari leave the centre, where crust-formation is replaced by abundant desquamation of the epidermis. The skin is thickened, assumes the character of parchment, and in old-standing cases becomes wrinkled.

The disease always commences along the back, withers, loins, and the upper part of the quarters. Thence it spreads to the flanks and sides of the chest. The psoroptes are almost exclusively confined to recently affected points on the edges of the scabby patches. They are visible to the naked eye, and appear as little whitish-brown points.

Scab is specially liable to attack a flock containing lambs and yearling sheep, whose skin is thin, fine and supple, and therefore more susceptible to their attacks. If a portion of a scabby flock be shorn, the shorn animals will probably recover on account of the psoroptes transferring themselves to the animals with long fleeces.

=The diagnosis= is easy. Psoroptic mange cannot be mistaken for sarcoptic mange, on account of the different points affected.

Psoroptic mange only attacks regions covered by wool, and sarcoptic mange those free of wool. A microscopical examination of acari removed from the diseased animals will, however, immediately remove all doubt.

Nor can the disease be confounded with phthiriasis, the trichodectes being immediately distinguished from the psoroptes by their greater size and the shape of their head. Moreover, they are usually to be found on the front portions of the shoulders.

It is more likely to be mistaken for another disease, termed by some writers seborrhœa and studied and described by Delafond under the name of sebaceous folliculitis. This disease appears mostly in autumn, and attacks animals much exposed to the weather and on moist, cold soils. It begins with very violent pruritus, followed by biting and loss of portions of the fleece. The skin is red, inflamed and painful, and the wounds are covered with large quantities of yellowish acid discharge of a sticky and offensive nature. The treatment of this disease consists in placing the sheep in clean, dry, well-ventilated sheds. Recovery is assisted by clipping and the application of some emollient dressing to the diseased parts.

The ease with which the disease can be cured and the absence of parasites enable one to readily distinguish it from psoroptic mange (scab).

=Prognosis.= The disease is not specially grave, so long as only a few animals are affected, for it is not difficult to cure by isolation, good feeding, and proper external treatment; but if scab appears in a flock, the freedom with which the animals intermingle is such that all are rapidly attacked, and the irritation produced at once checks their growth and causes loss in condition. Many ewes give birth to small, feeble lambs, which are almost certain to die, and in any case the wool is considerably diminished in value.

Delafond estimated that psoroptic mange formerly attacked one thirty-fifth of all the sheep in France every year, causing damage to the extent of five francs per head. At the present time, and since proper sanitary laws have been instituted, it has become much less common.

During the bad season of the year the mortality is greater, and may reach as much as from 40 to 50 per cent. In cases where scab is accompanied by some other disease, such as distomatosis, it may even rise to 80 per cent.

The treatment is preventive and curative. =Preventive treatment= consists in separating the healthy from the diseased animals and in disinfecting the folds, sheds, etc.

=Curative treatment.= The first point in this treatment consists in improving the diseased animal’s food both as to quality and quantity.

It is to be observed that the parasite has more difficulty in living on robust and well-nourished animals. Moreover, observation shows that transference from poor land to rich pastures is sometimes in itself sufficient to bring about a spontaneous cure. Such, at least, is the belief of the Spanish sheep farmers in Estramadura and of the French shepherds.

The shepherd can do a great deal to arrest the course of the disease. If he is careful, zealous, intelligent and observant he will quickly note the first indications of the disease and, by isolating the animals, check its spread.

The second point consists in shearing the diseased animals, and this must be carried out at any season of the year. The money loss is sometimes important, but must be met, for otherwise treatment is impossible. In cases of localised scab, empyreumatic oil, oil of cade, solutions of sulphuret of potassium, decoctions of black hellebore (water 1 quart, fresh rhizome 4 ounces or dry rhizome 2 ounces), decoction of tobacco and diluted tobacco juice (6 ounces in 1 quart of water) have been recommended. Such local treatment, however, is often useless, because incomplete.

When scab is generalised and it is impossible to define the parts attacked, general treatment is indispensable and the diseased sheep should be dipped.

As a preliminary, however, and in order to make sure that the application will produce its effect, the animals after shearing should be passed, twenty-four hours before the medicinal bath, through a warm bath containing soap in order to soften and remove the scabs. Applications of oil or some fatty substance will also soften the scabs, which may afterwards be removed with a scraper without producing bleeding. One pound of soft soap may be dissolved in fifty quarts of water and each sheep plunged into this and scrubbed with a brush for a few minutes. Washing alone removes a large number of the parasites.

Whatever bath be used it should not be given until four or five hours after the last feeding. The dips most popular in France are as follows:—

_Tessier’s Bath_ (1810).

For 100 sheep Arsenious acid 1½ parts or lbs.
„ Sulphate of iron 10 „
„ Water 100 „

The above materials should be boiled for ten minutes, and, as a consequence of the chemical fusion which occurs in the process, the proportion of arsenious acid dissolved amounts to about 2 drachms per quart instead of 3¾ drachms.

In this bath the arsenious acid acts as a parasiticide and the sulphate of iron as an astringent, the latter checking the absorption of toxic principles by the skin and sores, and preventing the sheep from licking themselves.

Absorption by the skin is not so dangerous as has been believed. Rossignol has shown that poisoning need not be feared in chemical baths unless the proportion of dissolved arsenic is above 150 grains per quart, especially if the period of immersion does not exceed five minutes. Even pure solutions of arsenic, free from any astringent, may be used, provided the quantity in the bath does not exceed 120 grains per quart.

The bath should, if possible, be kept warm—85° to 95° Fahr. (30° to 35° C.).

Four men are generally employed for the operation. One drives in the sheep, two others hold and brush them in the bath, and the fourth holds the head of the animal above the liquid. Tessier recommended gloves for the use of the operators, but experience has shown that such a precaution is unnecessary. The udder, and particularly the teats, of ewes with young may, if necessary, be smeared with some fatty substance, such as vaseline or oil, in order to guard against the astringent action of the liquid.

Each sheep is plunged in the bath for one or two minutes, or five minutes at the most. All the diseased spots must be brushed, rubbed and cleansed; but care must be taken not to make them bleed.

Tessier suggested leaving the animals for twenty-four hours in some disinfected place, without straw or food, to prevent these materials from being wetted by the liquid which runs from the fleece, and which, if afterwards eaten, might have a poisonous effect. Here, again, the danger has been exaggerated. Delafond has shown that sheep may be given a fluid ounce of Tessier’s bath for eight days running without producing the slightest unfavourable symptom.

Tessier’s bath is excellent from the therapeutic standpoint, but it imparts a yellow tint to the fleece, which is thus rendered less valuable. The mixture has therefore been modified in various ways.

_Clément’s Bath_ (1846).

For 100 sheep Arsenious acid 1·5 parts or lbs.
„ Sulphate of zinc 5 „
„ Water 100 „

In this bath every quart contains about 2½ drachms of arsenious acid. Its toxic power, therefore, is considerably greater than that of Tessier’s bath.

Clément’s formula has one drawback. The sulphate of zinc may be mistaken for a non-astringent alkaline sulphate (sulphate of soda), and as a consequence poisoning may occur, as experience has shown.

Mathieu of Sèvres replaced the sulphate of iron by an equal quantity of alum. In this case, each quart of the bath contains 2½ drachms of arsenious acid.

Clément’s and Mathieu’s formulæ have given just as good results as Tessier’s.

A last formula is that of Professor Trasbot. The aloes is of very little use, however, because it is almost insoluble.

For 100 sheep Arsenious acid 2 lbs.
„ Sulphate of zinc 10 „
„ Aloes 1 „
„ Water 25 gallons.

_Condition of the animals after the bath._—On leaving the bath the abraded parts are slightly cauterised. During the five or six following days the skin is stiff, and covered with adherent crusts over the points attacked by the parasites. The animals no longer scratch or bite themselves.

Towards the eighth day the crusts fall, the skin appears supple and of a pink colour, and the wounds cicatrise. In animals which have suffered for a long time recovery is much slower, and may extend over from thirty to fifty days. The wool again grows soft and bright, while the sheep rapidly regain their spirits and condition. The cicatrisation of the wounds is often accompanied by intense itching, which must not be taken as a sign of the persistence of the disease. It is well, however, to keep the animals under observation at this period.

Under any circumstances, six weeks or two months should always be allowed to elapse before giving a second bath. Should a few spots appear to be attacked secondarily, they may be moistened with a little of one of the bath liquids.

In Germany the creolin bath is generally employed:

For 100 sheep { Water 250 gallons or parts.
„ { Creolin 6·5 „

Each sheep is bathed a second time after an interval of one week, the animal being immersed for three minutes in the bath and thoroughly scrubbed with a brush. The efficacy of this method, however, is less certain.

In America, where the flocks are large and scabies is frequent, sulphur baths are employed, the baths themselves being of great size. The animals are forced to pass through them and remain there for some minutes.

The size and value of American, Australian, and New Zealand flocks demand that the modes of treatment practised and the experience gained in these countries should receive something more than passing notice. We therefore purpose giving a short _résumé_ of some parts of the very valuable monograph on sheep scab issued in 1897 by Dr. Salmon and Mr. Stiles, for the American Bureau of Animal Industry.

In selecting a dip the question of expense will naturally arise; next, the question as to whether or not scab actually exists in the flock to be dipped. The facilities at hand, the set-back to the sheep, and the length of the wool are also matters for consideration, as well as the pastures into which the dipped sheep are to be placed.

_Expense._—In estimating the expense one should consider not only the actual outlay for the ingredients of the ooze, but the cost of fuel and labour, the injury, if any, to the sheep, and the liability of not curing the disease. It is much more economical to use an expensive dip and cure scab, than it is to use a cheap dip and fail to cure it.

_Does scab exist in the flock?_—If scab does not actually exist and the wool is long, the dipping in this case simply being a matter of precaution, it is best not to select a dip containing lime.

_The facilities at hand for preparing dip._—If fuel is very scarce, so that it is impracticable to boil the mixture for at least two hours, the lime-and-sulphur dips should not be selected.

_The pastures._—In case it is necessary to place the dipped sheep on the same pastures they occupied before being dipped, it is always best to use a dip containing sulphur. If a proprietary dip is selected under those circumstances, it is suggested that sulphur be added, about 1 lb. of flowers of sulphur to every 6 gallons of dip. The object in using sulphur is to place in the wool a material which will not evaporate quickly, but will remain there for a longer period of time than the scab parasites ordinarily remain alive away from their hosts. By doing this the sheep are protected against reinfection.

Sulphur is one of the oldest known remedies for scab; its use is best known in the tobacco-and-sulphur dip and in the lime-and-sulphur dip. These home-made mixtures are the two dips which have played the most important _rôles_ in the eradication of scab from certain English colonies, and their use is extensive in America.

_The Tobacco-and-Sulphur Dip._

The formula as given here, and as adopted by the New South Wales sanitary authorities, appears to have first been proposed in 1854 by Mr. John Rutherford. “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. 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 cleansed with tobacco and sulphur. Judging, therefore, from the experience of the three colonies, there is no medicament or specific yet known that can be compared with tobacco and sulphur as a thorough and lasting cure for scab in sheep.” (Dr. Bruce, Chief Inspector of Sheep for New South Wales.)

The proportions adopted by Rutherford, and afterwards made official by the scab sanitary authorities, are—

Tobacco leaves 1 lb.
Flowers of sulphur 1 „
Water 5 gallons.

The advantage of this dip lies in the fact that two of the best scab remedies, namely, tobacco (nicotine) and sulphur, are used together, each of which kills the parasites, while the sulphur remains in the wool and protects for some time against reinfection. As no caustic is used to soften the scab, heat must be relied on to penetrate the crusts.

_Directions for preparing the dip._—Infusing the tobacco:—Place 1 lb. of gold-leaf or manufactured tobacco for every 6 gallons of dip desired in a covered boiler of cold or lukewarm water, and allow to stand for about twenty-four hours; on the evening before dipping bring the water to near the boiling point (212° Fahr.) for an instant, then remove the fire and allow the infusion to stand overnight.

Thoroughly mix the sulphur (1 lb. to every 6 gallons of dip desired) with the hand in a bucket of water to the consistency of gruel.

When ready to dip, thoroughly strain the tobacco infusion from the leaves by pressure, mix the liquid with the sulphur gruel, add enough water to make the required amount of dip, and thoroughly stir the entire mixture.

_Lime-and-Sulphur Dips._

Under the term “lime-and-sulphur dips” is included a large number, of different formulæ requiring lime and sulphur in different proportions.

To give an idea of the variety of the lime-and-sulphur dips, the following list is quoted, the ingredients being reduced in all cases to avoirdupois pounds and United States gallons:

(1.) The original “Victorian lime-and-sulphur dip,” proposed by Dr. Rowe, adopted as official in Australia:

Flowers of sulphur 20⅚ lbs.
Fresh slaked lime 10⁵⁄₁₂ „
Water 100 gallons.

(2.) South African (Cape Town) official lime-and-sulphur dip, February 4th, 1897:

Flowers of sulphur 20⅚ lbs.
Unslaked lime 16⅔ „
Water 100 gallons.

(3.) Fort Collins lime-and-sulphur dip:

Flowers of sulphur 33 lbs.
Unslaked lime 11 „
Water 100 gallons.

(4.) A mixture which, used to some extent by the Bureau of Animal Industry, contains the same proportions of lime and sulphur (namely, 1 to 3) as the Fort Collins dip, but the quantities are reduced to—

Flowers of sulphur 24 lbs.
Unslaked lime 8 „
Water 100 gallons.

In case of fresh scab Formula No. 4 will act as efficaciously as the dips with a greater amount of lime, but in cases of very hard scab a stronger dip, as the Fort Collins dip, should be preferred; or, in unusually severe cases, an ooze with more lime in proportion to the amount of sulphur, such as the Victorian (No. 1) or the South African (No. 2) dip might be used.

_Prejudice against Lime-and-Sulphur Dips._

There is at present great prejudice (a certain amount of it justified, no doubt) against the use of lime and sulphur, emanating chiefly from the agents of patent or proprietary dips and from the wool manufacturers.

In the first place, it is frequently asserted that lime and sulphur does not cure scab. Experience in Australia and South Africa, as well as in America, has shown beyond any doubt that a lime-and-sulphur dip, when properly proportioned, properly prepared, and properly used, is one of the best scab eradicators known.

It is claimed by some that it produces “blood poisoning.” But the cases of death following the use of lime-and-sulphur dips have been infinitesimally few when compared with the number of sheep dipped in these solutions, and when compared with the deaths which have been known to follow the use of certain proprietary dips. The details of such accidents, so far as they have been reported, have not shown that death was due to any property prepared and properly used lime-and-sulphur dip. It is highly probable that the cases of so-called “blood poisoning” of shear-cut sheep are generally due to an infection with bacteria in stale dip containing putrefying material.

The greatest objection raised against the use of lime-and-sulphur dip is that it injures the wool. This objection is raised by many wool manufacturers and echoed with ever-increasing emphasis by the manufacturers of prepared dips; while, after years of extensive experience with properly prepared dip, its injury to the wool is strongly and steadfastly denied by the Agricultural Department of Cape Colony.

It is believed that a certain amount of justice is attached to this objection to lime and sulphur as generally used; unless, therefore, lime and sulphur can be used in a way which will not injure the wool to an appreciable extent, we should advise against its use in certain cases; in certain other cases the good accomplished far outweighs the injury it does. Let us, therefore, examine into this damage and its causes.

The usual time for dipping sheep is shortly after shearing, when the wool is very short; whatever the damage at this time, then, it can be only slight, and the small amount of lime left in the wool will surely do but little harm.

In full fleece lime and sulphur will cause more injury. In Australia the deterioration was computed by wool buyers at 17 per cent., although in Cape Colony the Department of Agriculture maintains that if properly prepared, and if only the clear liquid is used, the sediment being thrown away, the official lime-and-sulphur formula will not injure the long wool. The United States Bureau of Agriculture have found some samples of wool injured by dipping, while on other samples no appreciable effect was noticeable.

If a lime-and-sulphur dip is used, care must be taken to give the solution ample time to settle; then only the clear liquid should be used, while the sediment should be discarded. In some of the above tests on samples of wool it was found that the dip with sediment had produced very serious effects, even when no appreciable effects were noticed on samples dipped in the corresponding clear liquid.

Experience has amply demonstrated that a properly made and properly used lime-and-sulphur dip is one of the cheapest and most efficient scab eradicators known, but its use should be confined to flocks in which scab is known to exist, and to shorn sheep, with the exception of very severe cases of scab in unshorn sheep. It should only be used when it can be properly boiled and settled. The use of lime-and-sulphur dips in flocks not known to have scab, especially if the sheep are full fleeced, cannot be recommended; in such cases tobacco, or sulphur and tobacco, is safer and equally good.

All things considered, where it is a choice between sacrificing the weight of sheep and to some extent the colour of the wool by using tobacco and sulphur, and sacrificing the staple of the wool by using lime and sulphur, the owner should not hesitate an instant in selecting tobacco in preference to lime. The loss in weight by using tobacco and sulphur is not much greater than the loss in using lime and sulphur, while the loss in staple is of more importance than a slight discoloration.

_Preparation of the mixture._—Take 8 to 11 lbs. of unslaked lime, place it in a mortar-box or a kettle or pail of some kind, and add enough water to slake the lime and form a “lime paste” or “lime putty.”[8]

Footnote 8:

Many persons prefer to slake the lime to a powder, which is to be
sifted and mixed with sifted sulphur. One pint of water will slake 3
lbs. of lime if the slaking is performed slowly and carefully. As a
rule, however, it is necessary to use more water. This method takes
more time and requires more work than the one given above, and does
not give any better results. If the boiled solution is allowed to
settle the ooze will be equally safe.

Sift into this lime paste three times as many pounds of flowers of sulphur as of lime, and stir the mixture well.

Be sure to weigh both the lime and the sulphur. Do not trust to measuring them in a bucket or to guessing at the weight.

Place the sulphur-lime paste in a kettle or boiler with about twenty-five to thirty gallons of boiling water, and boil the mixture for two hours at least, stirring the liquid and sediment. The boiling should be continued until the sulphur disappears, or almost disappears, from the surface; the solution is then of a chocolate or liver colour. The longer the solution boils the more the sulphur is dissolved and the less caustic the ooze becomes.

Pour the mixture and sediment into a tub or barrel placed near the dipping vat and provided with a bung-hole about 4 inches from the bottom, and allow ample time (two to three hours, or more if necessary) to settle.

When fully settled draw off the clear liquid into the dipping vat, and add enough water to make a hundred gallons. _Under no circumstances should the sediment be used for dipping purposes._

To summarise the position of the United States Department of Agriculture on the lime-and-sulphur dips:—When properly made and properly used these dips are second to none and equalled by few as scab eradicators. There is always some injury to the wool resulting from the use of these dips, but when properly made and properly used upon shorn sheep, it is believed that this injury is so slight that it need not be considered; on long wool the injury is greater and seems to vary with different wools, being greater on a fine than on a coarse wool. This injury consists chiefly in a change in the microscopic structure of the fibre, caused by the caustic action of the ooze. When improperly made and improperly used the lime and sulphur dips are both injurious and dangerous, and in these cases the cheapness of the ingredients does not justify their use. In case scab exists in a flock and the farmer wishes to eradicate it, he cannot choose a dip which will bring about a more thorough cure than will lime and sulphur (properly made and properly used), although it will be perfectly possible for the farmer to find several other dips which will, when properly used, be nearly or equally as effectual as any lime-and-sulphur dip. There is no dip to which objections cannot be raised.

_Arsenical Dips._

There are both home-made arsenical dips and secret proprietary arsenical dips. It is well to use special precautions with both, because of the danger connected with them. One of the prominent manufacturers of dips, a firm which places on the market both a powder arsenical dip and a liquid non-poisonous dip, recently summarised the evils of arsenical dips in the following remarkable manner:

“The drawbacks to the use of arsenic may be summed up somewhat as follows: (_a_) Its danger as a deadly poison. (_b_) Its drying effect on the wool. (_c_) Its weakening of the fibre of the wool in one particular part near the skin, where it comes in contact with the tender wool roots at the time of dipping. (_d_) Its not feeding the wool or stimulating the growth, or increasing the weight of the fleece, as good oleaginous dips do. (_e_) The danger arising from the sheep pasturing, after coming out of the bath, where the wash may possibly have dripped from the fleece, or where showers of rain, after the dipping, have washed the dip out of the fleece upon the pasture. (_f_) Its occasionally throwing sheep off their feed for a few days after dipping, and so prejudicing the condition of the sheep. (_g_) Its frequent effect upon the skin of the sheep, causing excoriation, blistering, and hardness, which stiffen and injure the animal, sometimes resulting in death.”

Although this manufacturer has gone further in his attack upon arsenic than the United States Bureau of Agriculture would have been inclined to do, it must be remarked that when a manufacturer of such a dip cannot speak more highly of the chief ingredient of his compound than this one has done in the above quotations, his remarks tend to discredit dips based upon that ingredient. Bruce, the Chief Inspector of Live Stock for New South Wales, speaking of arsenical dips, says: “Arsenic and arsenic and tobacco (with fresh runs) cured 9,284 and failed with 9,271.”

It may be said, on the other hand, that arsenic really has excellent scab-curing qualities; it enters into the composition of a number of the secret dipping powders, and forms the chief ingredient in one of the oldest secret dips used. This particular dip has been given second place (with some qualifications) among the officially recognised dips in South Africa.

_Formulæ for arsenical dips._—Finlay Dun recommends the following:—Take 3 lbs. each of arsenic, soda ash (impure sodium carbonate) or pearl ash (impure potassium carbonate), soft soap, and sulphur. A pint or two of naphtha may be added if desired. The ingredients are best dissolved in 10 to 20 gallons of boiling water, and cold water is added to make up 100 gallons. The head of the sheep must, of course, be kept out of the bath.

A mixture highly endorsed by certain parties consists of the following ingredients:

Commercially pure arsenite of soda 14 lbs.
Ground roll sulphur 34½ „
Water 432 gallons (U.S.)

The arsenite of soda is thoroughly mixed with the sulphur before being added to the water.

_Precautions in use of arsenical mixtures._—Any person using an arsenical dip should bear in mind that he is dealing with a deadly poison. The following precautions should be observed:

(1) Yards into which newly-dipped sheep are to be turned should first be cleared of all green food, hay, and even fresh litter; if perfectly empty they are still safer. (2) When the dipping is finished, the yard should be cleaned, washed, and swept, and any unused ooze should at once be poured down a drain which will not contaminate food or premises used by any animals. (3) Dipped sheep should remain in an open, exposed place, as on dry ground. (4) Overcrowding should be avoided, and every facility given for rapid drying, which is greatly facilitated by selecting fine, clear, dry weather for dipping. (5) On no account should sheep be returned to their grazings until they are dry and all risk of dripping is passed.

The feeling of the United States Bureau of Agriculture towards arsenical dips is shown by the following:

_Suggestion as to danger._—The formulæ given above are copied from the writings of men who have had wide experience in dipping, but this Bureau assumes no responsibility for the efficacy of the dips given, or for their correct proportions. Furthermore, as long as efficacious non-poisonous dips are to be had, we see no necessity for running the risks attendant upon the use of poisonous dips.

_Carbolic Dips._

This class of dips kills the scab mites very quickly, but unfortunately the wash soon leaves the sheep, which is consequently not protected from reinfection in the pastures. If, therefore, a carbolic dip is selected, it is well to add flowers of sulphur (1 lb. to every 6 gallons) as a protection against reinfection.

The advantages of carbolic dips are that they act more rapidly than the tobacco or sulphur dips, and that the prepared carbolic dips are very easily mixed in the bath. They also seem, according to Gillette, to have a greater effect on the eggs of the parasites than either the sulphur or the tobacco dips. The great disadvantages of this class of dips are—first, in some of the proprietary dips, that the farmer is uncertain regarding the strength of material he is using; second, the sheep receive a greater set-back than they do with either lime and sulphur or tobacco.

The United States Bureau of Agriculture is inclined to be extremely conservative in regard to them, and to advise their manufacturers to prepare them in a guaranteed strength with more explicit directions for use than are to be found in the present circulars.

One of the prominent proprietary carbolic dips was formerly recognised as one of the three official dips in New South Wales, but it has now been erased from the list. In Cape Town carbolic dips are not much used, and in the official reports little is said concerning them.

The United States Bureau of Animal Industry gives the following advice as regards dipping:

(1.) Select a dip containing sulphur. If a prepared “dip” is used which does not contain sulphur, it is always safer to add about 16½ lbs. of sifted flowers of sulphur to every 100 gallons of water, especially if, after dipping, the sheep have to be returned to the old pastures.

(2.) Shear all the sheep at one time, and immediately after shearing confine them to one-half the farm for two to four weeks. Many persons prefer to dip immediately after shearing.

(3.) At the end of this time dip every sheep (and every goat also, if there are any on the farm).

(4.) Ten days later dip the entire flock a second time.

(5.) After the second dipping, place the flock on the portion of the farm from which they have been excluded during the previous four or five weeks.

(6.) Use the dip at a temperature of 100° to 110° Fahr.

(7.) Keep each sheep in the dip for two minutes by the watch—do not guess at the time—and duck its head at least once.

(8.) Be careful in dipping rams, as they are more likely to be overcome in the dip than are the ewes.

(9.) Injury may, however, result to pregnant ewes, which must on this account be carefully handled. Some farmers arrange a stage, with sides, to hold the pregnant ewes, which is lowered carefully into the vat, and raised after the proper time.

(10.) In case a patent or proprietary dip, especially an arsenical dip, is used, the directions given on the package should be carried out to the letter.

CHORIOPTIC MANGE, SYMBIOTIC MANGE, FOOT SCAB.

This disease was studied in Germany by Zürn in 1874, and by Schleg in 1877. It has not yet been seen in France.

=Causation.= The sole cause is the presence of _Chorioptes scabiei_ (_v. ovis_). Contagion is favoured by the animals being in poor condition. The disease extends very slowly. Only 2 to 3 per cent. of the animals are affected, and the sufferers are usually those with fine skins.

German shepherds consider this disease to be due to an excessive allowance of salt, because it is most common during the winter, when the sheep are housed. Needless to say, this theory is incorrect.

=Symptoms.= Sometimes this form of mange attacks the limbs and develops very slowly. It commences about the pasterns, and gradually extends upwards towards the knee or hock. It really advances beyond these points. The parasites are much smaller than those of common scab, and are often overlooked. The sheep stamp their feet and scratch and bite the infected parts, sometimes transferring the disease to the lips and face, where it may persist for a time.

In very old standing cases which have been entirely neglected, it may be met with in the region of the armpit and thigh, the limbs becoming swollen so as to suggest lymphangitis. In the folds of the hock and pastern the thickening of the skin may lead to the formation of yellowish or brownish crusts, according to whether the exudation is merely of a serous character or accompanied by bleeding.

=The diagnosis= is easy. The parasites are found in the thickness of the crusts, and are readily recognised under the microscope.

=The prognosis= is not grave, because of the comparative rarity of the disease and its mildly contagious character. This disease, moreover, never attacks the head or body, but remains localised in the lower portions of the limbs.

=Treatment.= The crusts should be removed by washing or by standing the animals for a time in warm water. Simple cleanliness often suffices, but, to save time, some anti-parasitic may be used. The condition is easily cured even without disinfecting the folds.

MANGE IN THE OX.

Bovine animals may be attacked by three varieties of mange, all of which have long been known.

SARCOPTIC MANGE.

This is not of any great clinical importance, as it is purely accidental, and only results from the conveyance of sarcoptes from other animals, such as the horse, sheep, dog, goat or cat, to an animal of the bovine species. That the disease does occur, however, is shown by the following excerpt from a report by Professor McFadyean: The animal showed no symptom of skin disease at the time of purchase, but soon after it was brought home it was noticed to be rubbing, and the skin began to assume an unhealthy appearance. When seen in January (four months after purchase) it was rather poor, although it had been in very good condition when sold. Almost the entire skin had become affected, including that of the legs down to the top of the hoofs. There had been extensive loss of hair, and the skin was thick, grey, wrinkled, and dry. At some places it had become thrown into thick folds. Only a few scabs or crusts had formed where the animal had recently rubbed itself. In some scurf scraped from what seemed to be the parts most recently invaded, numbers of acari were without much difficulty found with the microscope.

A good many cases of mange of undetermined character have been reported as occurring among cattle in various parts of England during the last year or two, and in a number of instances the disease was believed to have been contracted during exhibition at a show. It is not improbable that some or all of these were cases of this sarcoptic mange, and in view of its very contagious character it is desirable that care should be taken to exclude from shows animals exhibiting any symptom of the disease.

PSOROPTIC MANGE.