Chapter II: Phthiriasis (2)

This condition has also been termed dermatodectic mange. This is very rare, and, like the former, of trifling clinical importance.

=Causation.= It is due to infection with _Psoroptes communis_ (_v. bovis_). Poor condition, want of grooming, bad hygienic surroundings and general neglect, facilitate its spread.

=Symptoms.= It commences at the base of the neck, in rarer cases at the sides of the neck, along the withers, and at the root of the tail; thence it gradually attacks the croup, loins, back, shoulders, sides of the chest, and finally all the body with the exception of the limbs.

It produces violent itching, the animal continually scratching itself, even causing raw sores. At first the epidermis is elevated in little miliary points, which may be isolated or confluent, and are filled with serosity. This fluid discharges, gluing together the hairs; it then hardens and produces adherent crusts, which increase in number and size. The skin exhibits large numbers of bare, mangy points; these have irregular margins, and are covered with thick, grey, scaly crusts. The psoroptes are found under these crusts.

The skin becomes hard, dry, fissured and cracked, and sometimes forms large folds on the sides of the neck, shoulders and chest.

The influence of the seasons on the development of this disease has been well shown by Gerlach and Muller. The disease commences about the end of autumn, when the animals are stabled. It continues to extend until February, but diminishes as soon as the animals return to the fields in spring. The crusts fall, the hair again grows, and the animal appears to be cured, but the disease again revives during the autumn. The psoroptes lie hidden during the summer round the poll and the horns. The disease seldom attacks animals at grass and in good condition, or those over three years old. Calves, yearlings, and two-year-olds in poor condition suffer most.

When the disease is very extensive, the animals lose condition and may even die.

=Diagnosis.= Psoroptic mange in the ox may be mistaken for several cutaneous diseases, to which it has a certain resemblance, as for instance phthiriasis and the first stage of ringworm.

These different diseases, however, show their own distinctive symptoms on a careful examination.

=The prognosis= only becomes grave when the disease has been neglected and the animals are greatly reduced in condition. When recent, this form of mange can readily be cured by the application of parasiticides.

=Treatment.= As in dealing with all transmissible diseases, the animals must be isolated and washed with soap, and the diseased parts must be dressed with some parasiticide, such as sulphur ointment. The best preparations are: Benzine and petroleum in equal quantities; concentrated solution of sulphuret of potassium (8 ounces to the quart); Helmerich’s ointment; diluted creolin solution; decoctions of tobacco; ointment of pentasulphuret of potassium, and oil of cevadilla.

One or two applications are generally sufficient to effect a cure, and relapses are not likely to take place if the stable is disinfected. In America the disease is common in the West and North-West, where it is treated by the lime-and-sulphur bath recommended for sheep scab (which see). Large vats are constructed, and the oxen are lowered into these by means of a wooden cage controlled by machinery, which is operated either by a small engine or more frequently by a horse.

The food should be of good quality, for good general health plays a great part in resisting parasitic invasions.

CHORIOPTIC MANGE.

This disease has also been termed dermatophagic and symbiotic mange.

It was first described in 1835 by Kégélaar, and has been the subject of investigation by Hering, Gerlach, Delafond, and Mégnin.

=Causation.= It is produced by the _Chorioptes bovis_, and is transferred with difficulty, even by cohabitation.

=Symptoms.= This form of mange in the ox does not affect the same parts as in other animals. In the horse, etc., it attacks the limbs, whilst in the bovine species it is usually found at the base of the tail. It causes slight itching. The diseased region becomes covered with numerous little pellicles, the hairs gradually fall, crusts form, and the skin shows deep cracks. When the disease is completely neglected, it may extend to the loins, back, sides of the body and shoulders. It may also affect the perineal region, the inner surface of the thighs, and in fact the whole of the body if the animals are young and in poor condition.

=Diagnosis.= At the outset it is difficult to distinguish between chorioptic and psoroptic mange, and the use of the microscope is necessary. On a superficial examination chorioptic mange may be mistaken for phthiriasis when the latter attacks the posterior portions of the body, particularly the base of the tail, and when it is accompanied by eruptions, loss of hair, and intense itching.

The distinction between the two conditions, however, is extremely easy after an examination of the two parasites.

=Prognosis.= The disease is of slight gravity, and does not threaten the animal’s health unless neglected for so long a time that the parasites invade all parts of the body. In that case the disease may cause anæmia and loss of condition.

=The treatment= of this form of mange comprises nothing special, it being sufficient to proceed as directed in the previous article.

The stables ought always to be thoroughly disinfected.

MANGE IN THE GOAT.

The goat suffers from the attacks of sarcoptes, psoroptes, and chorioptes, but up to the present time only two forms of mange have been described, sarcoptic and chorioptic mange.

Psoroptes have only been found about the eye, where the disturbance they produce is comparatively trifling.

SARCOPTIC MANGE.

This disease was noticed in 1818 in goats imported into France from Thibet.

Henderson published the history of a Persian goat which conveyed sarcoptic mange to men and horses. In 1851 Walraff noticed an epizootic mange which attacked the goats in the Prattigau valley of Switzerland, which was transmitted to men and sheep and which exhibited the clinical characters of sarcoptic mange.

=Causation.= This disease is due to the presence of _Sarcoptes scabiei_ (_v. capræ_).

It sometimes occurs in an epizootic form, as Walraff’s observations show, but it seems specially to attack goats in Asia and Africa.

This mange may be transmitted by the goat to sheep, in which animals it attacks the head and muzzle; it is particularly contagious in sheep having coarse, dry fleeces.

Similarly sarcoptic mange of sheep may be conveyed to the goat, in which animal it extends all over the body.

=Symptoms.= This mange causes intense itching. It first attacks the head and ears, then the trunk, belly, udder, and limbs. If the disease is neglected it becomes generalised very rapidly, and the animals waste away and die in a very short time.

At the commencement little crusts, which discharge a viscous liquid, are found about the head. The goats rub themselves raw, and, as in facial mange of sheep, there appear dry, scaly, branlike patches. After a time the diseased area extends, the wool falls, and the skin becomes dry, thick and wrinkled. The appearance is exactly like that of sarcoptic mange in sheep, the lower part of the head being seldom invaded. The animals lose condition, waste and die of exhaustion.

=Diagnosis.= The parasite is readily recognised, and the practitioner, moreover, is often put on his guard by the epizootic character assumed by the disease.

=The prognosis= is grave. Walraff declared the mortality in Grisons (Switzerland) to be as high as 20 per cent.

=The treatment= is identical with that of psoroptic mange in sheep. After the animals have been sheared and washed with soap, they should be completely immersed in a bath of the character mentioned in connection with sheep scab. If only one animal is infected, it may be sufficient to dress it repeatedly with an ointment containing some parasiticide.

CHORIOPTIC MANGE.

This form of mange was noted by Delafond in 1854 at the Jardin des Plantes (Paris) in some angora goats, and by Mollereau in 1889. The disease studied by Delafond had invaded both sides of the neck, the eyes, withers, back, loins, and base of the tail. It was characterised by partial loss of hair, the finer hair falling and the coarser remaining in position.

In Mollereau’s case the disease was located in one of the hind pasterns, and assumed the form of a thickened band, which produced an œdematous swelling. The chorioptes were discovered in a thick crust formed by the drying on the hair of the discharge due to their punctures.

=Diagnosis.= The parasites can easily be found under the crusts, and, once recognised, distinguish the disease from any other infection.

=Treatment.= Ointments containing some parasiticide and solutions of sulphuret of potassium generally suffice, the disease having little tendency to become generalised.

MANGE IN THE PIG.

The pig suffers from one variety only of mange. It was described by Viborg, Gürlt and Spinola, who found a sarcopt in the mange of wild boars in 1847. Hertwig and Gerlach made a similar observation some years later. Delafond in 1857 discovered the sarcopt of mange in the pig.

=Causation.= Sarcoptic mange in the pig is due to the presence of _Sarcoptes scabiei_ (_v. suis_), although the pig may contract (temporarily) the sarcoptic mange of goats.

Contagion is favoured by poor condition, over-crowding, dirt and bad hygienic surroundings.

The primitive races of pigs resist the disease better than the improved races. This mange can be conveyed to man and to other animals.

=Symptoms.= It usually commences about the head, ears, and eyes, and extends to the quarters, internal surface of the thighs, etc. In the early phases it is impossible to discover the little galleries under the epidermis, but closely placed reddish papules may be seen. The active proliferation of the epidermis, together with discharge, causes the formation of dry crusts of a greyish-white, silvery tint, adherent while still thin, easy to detach at a later stage, and sometimes ⅜ of an inch in thickness. The skin becomes wrinkled, the bristles are shed or loosened in their follicles, and are glued together in little bunches before falling. As these patches extend over the whole surface of the body, the animal appears to be bespattered with dry guano (Muller).

Under the crusts the skin is rough, excoriated, and, about the thorax and abdomen, is indurated, and sometimes measures 1 to 1½ inches in thickness. In other parts, particularly at the base of the ears, the papillæ are hypertrophied; they become as large as a pea, or even a bean, and, lifting the crusts which cover them, assume the appearance of the warts sometimes found on the cheeks of dogs or the teats of cows. Sarcoptes may be found under these epidermic growths, though in order to obtain them the skin must be scraped until it almost bleeds.

The dimensions of these parasites render them visible to the naked eye. They are the largest variety of the sarcoptinæ, the egg-bearing female being half a millimètre in length. Guzzoni has found in the ears specimens of smaller size.

Mange in pigs develops slowly. When it affects the whole body, it prevents fattening and causes loss of condition.

=Diagnosis.= This is the only parasitic disease which affects the entire surface of the body and presents these peculiar powdery crusts.

=Treatment.= All the styes should first be carefully disinfected. Treatment is commenced by vigorously scrubbing the animal with a brush dipped in soap and water, and thus getting rid of the crusts as far as possible.

The animals are afterwards dressed with decoctions of tobacco, with Helmerich’s ointment, or the other mixtures above mentioned.

DEMODECIC MANGE.

This mange is produced by parasites of the family Demodecidæ (_Demodex folliculorum_), which live in the hair follicles and sebaceous glands of several species of mammals.

DEMODECIC MANGE IN THE OX.

This was described in 1845 by Gros, and in 1878 was found by Faxon in Illinois in the skins of cows prepared for tanning. It has not been met with in France. The skins examined by Faxon showed numerous rounded enlargements, resulting from dilatation of the hair follicles in the regions of the neck and shoulders.

By pressing on these enlargements a whitish, greasy, sebaceous material was ejected, very rich in demodectes.

DEMODECIC MANGE IN THE GOAT.

This was first noticed by Niederhaüsern, at the Bern Veterinary College, in a goat which showed little nodosities over different parts of the trunk, varying in size between that of a pea and that of a hazel-nut. By forcibly compressing these enlargements a yellowish-grey semi-solid material, containing a considerable number of demodectes, was caused to exude.

In 1885 Nocard and Railliet found the same parasite in a young he-goat; the pustules were spread over the sides and flank. =Treatment= consists in opening the pustules and dressing them a few times with an anti-parasitic lotion.

DEMODECIC MANGE IN THE PIG.

This was well described for the first time by Csokor. It was afterwards seen by Neumann and Lindqvist.

The isolated pustules are of the size of a grain of sand, but when confluent may reach the size of a hazel-nut. They are sometimes dark in colour, often deep-seated, are surrounded by a zone of inflammation, and appear in places where the skin is fine (the groin, neck, belly, etc.). The demodex becomes lodged and multiplies, not in the hair follicles, but in the sebaceous glands. Csokor regarded this disease as contagious; in a herd of one hundred he found twenty-two pigs affected with it. Lindqvist, however, found but one case in a herd of two hundred.

NON-PSOROPTIC FORMS OF ACARIASIS.

These are produced in farm animals by arachnide belonging to the families of Trombidiidæ and Ixodidæ.

(1.) =The Leptus autumnalis= is considered to be the larva of the _Trombidium Holoscriceum_, or silky trombidion. It lives in late summer and autumn, in the grass.

=Symptoms.= The animals show intense itching, and cannot sleep owing to burning sensations. They continually rub themselves, and thus, secondarily, produce excoriated papules and patches resembling those of eczema. When the papules are very numerous, particularly if the animals are thin-skinned, more or less extensive erythema may be produced.

At the points attacked the skin swells, becomes red, and sometimes even violet, and exhibits irregular, isolated or confluent swellings, ¼ to ⅜ of an inch in diameter.

The parasite most commonly becomes fixed round the lips, the forehead, the cheeks, the sides of the neck, and the extremities.

=The diagnosis= is easy, the discovery of the parasite removing all doubt.

The condition is of slight importance. The parasites do not live for more than a few days on the animal’s skin, so that they only produce temporary disturbance.

=Treatment= consists in bathing the parts with some lotion, such as 2 to 3 per cent. creolin or 2 per cent. chloral, or in applying mixtures of oil and petroleum, etc.

(2.) =Ixodes hexagonus=, =I. ricinus=, and other species of the tick family (Ixodidæ) attack sheep, goats, and oxen in France.

=Symptoms.= In sheep the ixodidæ usually affix themselves at points where the skin is tender and unprotected by wool, as for instance the thighs, armpit, and upper part of the neck. Their bites produce irritation, followed by an intense burning sensation, and the formation of a red blush round the point bitten.

In the ox the ticks fasten on the neck, behind and within the ears, and also wherever the skin is tender. Until the last few years little importance was attached to their development, but since it has been proved that _Rhipicephalus annulatus_ is the active factor in desseminating Texas fever, ticks have attracted much attention.

It seems, moreover, to be proved by the researches of Lignières that a form of piroplasmosis exists in France, and it seems possible that the _Ixodes ricinus_ may be a means of propagation.

=The diagnosis= of acariasis produced by ticks is easy, for the parasites attain large dimensions.

=Prognosis.= It is difficult at present to say what importance should be attached to this form of acariasis, but its existence and possible consequences should be noted.

=Treatment.= Some authors have recommended killing the ticks by touching them with benzine, petroleum, essence of turpentine, etc., but these methods do not always succeed. Applications of concentrated solution of chloral are more effective. When the parasites are so large as to render this possible it is better to remove them by hand, taking care at the same time to remove the rostrum, which, if left in place, might cause more or less suppuration. In countries where ticks are numerous and large numbers of cattle are infested, the parasites are destroyed by smearing and dipping.

(The cattle ticks of America are of especial importance in relation to the disease known as Texas fever. Those who wish to study the entomology of this subject are referred to the masterly account and fine coloured illustrations of Salmon and Stiles, “Cattle Ticks of the United States,” Ann. Rep. U.S.A. Bureau of Agriculture, 1900, p. 380.)

HYPODERMOSIS IN THE OX (WARBLES).

=Causation.= This is a parasitic disease characterised by subcutaneous swellings due to the presence of larvæ of the _Hypoderma bovis_. The larva is met with throughout Europe. It attains the perfect stage during the summer, from the middle of June to the commencement of September.

The female deposits her eggs on animals with fine skins. These eggs are elliptical, and provided with a kind of tail of a brownish colour. They soon become converted into larvæ, provided with rows of little spines.

The manner in which the eggs are laid is not exactly understood, nor are we better informed regarding the hatching of the young larvæ. Until recently it was believed that the larva perforated the skin as soon as it quitted the egg, and then penetrated as far as the subcutaneous connective tissue. Recent observations, however, have upset this view. It is probable that this larva, like other gastrophili, is swallowed by animals of the bovine species, and passes through the intestine into the surrounding tissues by a path which is yet unknown, possibly by the blood-vessels, whence it makes its way after a longer or shorter interval into the subcutaneous connective tissue.

Certain recent observations seem to support the latter view, which is also corroborated by known facts regarding hypodermic myiosis in man. The eggs are laid in summer, and the swellings indicating the presence of the larvæ only appear during the winter. Henrichsen found young larvæ in the fatty tissue situated between the periosteum and spinal dura mater, between the period from December to March.

=Symptoms.= Whatever the mode of development of the larvæ, cutaneous swellings appear between the months of February and March on the back, lumbar region, quarters, shoulders and ribs, and, less frequently, over the chest, belly and thighs.

They vary in number. Commonly there are from ten to twenty, and it is only in rare cases that less than four or five are found. As soon as they attain the subcutaneous connective tissue they act as foreign bodies, causing a circumscribed inflammation, and finally suppuration. In this way the so-called “warbles” are produced.

Each larva is surrounded by a thick wall, forming a cavity, which communicates with the outer air by a minute aperture.

When the swelling is sufficiently advanced the larva may be extricated by pressing with the fingers around the base of the warble. A few days before it leaves its shelter the larva enlarges the little opening by thrusting its last rings into it. Soon after the larva has escaped the discharge of pus ceases, and the skin wound heals.

=Diagnosis.= The times at which the swellings appear and the larvæ are present render the diagnosis easy.

=Prognosis.= This is seldom grave, for the larvæ rarely cause death. In cases where they are present in very large numbers, however, they may set up purulent infection.

=Treatment.= No really effective treatment against warbles is known. Curative treatment consists in squeezing out or killing the larvæ when in the subcutaneous tissue, but this is practically useless, as the dead larvæ then set up prolonged suppuration.