SECTION VIII.. Diseases of the Skin and Subcutaneous Connective Tissue.

DISEASES OF THE SKIN AND SUBCUTANEOUS CONNECTIVE TISSUE.

CHAPTER I. ECZEMA.

Under the name of eczema may be grouped a series of cutaneous diseases characterised by pruritus, by a discharge from the skin, or simply by epidermic proliferation, without any apparent parasitic or accidental cause.

These diseases have been referred to a special constitutional condition termed a diathesis, although during the last few years we have come to recognise certain microbic and toxic influences in their production. In the ox eczema assumes different appearances. Accordingly, the disease has been divided into the acute, chronic, sebaceous, and toxic forms.

ACUTE ECZEMA.

=Causation.= In the ox, as in all other species, the determining cause is to be found in bad hygienic conditions, improper feeding, and in a special individual condition of the animal affected, that is to say, a diathesis.

=Symptoms.= During a preliminary period, which might be termed a prodromic period, only general symptoms can be detected, such as fever, loss of appetite, digestive disturbance, constipation, etc. Local signs are still absent, or at least are not noticeable, and are only represented by congestion of the skin.

The second phase is characterised by a papulous eruption which is difficult to detect, inasmuch as it occurs in the depths of the coat. Nevertheless, the skin is distinctly sensitive, and at numerous small points the hairs appear to stand upright.

The third phase consists in the development of more or less confluent vesicles, with exudation and discharge. The disease is not really visible externally until after the hair has become agglutinated by the discharge. This discharge is seldom as abundant as in eczema in the dog or horse. It is produced slowly and dries rapidly.

As the crusts fall, carrying with them a portion of the hair, the general symptoms disappear, but the sites of these vesicular patches now show cracks extending as deep as the dermis and often complicated by secondary infection involving suppuration, adenitis, abscess formation, or diffuse subcutaneous suppuration.

Acute eczema is generally confined to the limbs. It may develop fully in from twenty-four to forty-eight hours. The acute stage is attained in a few days, and the condition disappears in two to three weeks provided it does not assume the chronic form as the result of complications.

=Diagnosis.= The absence of parasites enables the condition to be distinguished from phthiriasis and acariasis, whilst the history prevents its being confounded with toxic eczema.

=Prognosis.= The condition is troublesome rather than grave. Suppuration is often persistent, and despite careful attention the discharge may only diminish slowly, while the disease is always liable to return.

=The treatment= is local and general. Local treatment consists in emollient and antiseptic washes and the application of drying powders. The former comprise glycerole of starch, bran water, boric ointments, camphorated vaseline, iodine and glycerine. At a later stage the skin can be washed with decoction of oak bark or a weak iodine solution, followed by the application of talc or starch powder. As far as possible this external treatment should be supplemented by the frequent use of mild purgatives and various diuretics, which seem to have a special action on the arthritic diathesis.

CHRONIC ECZEMA.

Comparatively few cases of chronic eczema have hitherto been described in oxen, and the details given are extremely meagre. Chronic eczema may assume that form from the first or may succeed acute eczema. The causes are probably the same in both conditions.

=The symptoms= appear to be those of the acute form, but are much less severe. They consist in papulation, a miliary vesicular eruption, pruritus, and the formation of crusts and epidermic scales.

In a case seen by Mégnin the crusts separated and fell away, leaving bare spots. The disease re-appeared for several years in succession. The spots finally remained bare, but showed no thickening of the skin and no microscopic changes.

=Diagnosis.= Microscopical examination is necessary to distinguish this disease from scabies or ringworm.

=The prognosis= is grave, because large areas of the skin may be invaded in succession.

=Treatment.= As in acute eczema, the condition is improved by the prolonged administration of small doses of salines and diuretics. Arsenical preparations are also valuable, but should only be employed for two or three weeks together, with intervals of equal duration. The dangerous complications which sometimes result from accumulations of this drug in the system are thus avoided.

SEBACEOUS OR SEBORRHŒIC ECZEMA.

Whilst the two preceding forms of eczema result from vascular disturbance of the skin or dermis that now under consideration seems due to vascular and secretory troubles in the accessory structures of the skin, and more particularly in the sebaceous glands.

=Symptoms.= The disease develops slowly. At first circular or elliptical patches of skin, distributed regularly over the body, more especially round the natural orifices, become deprived of hair. The surface of these patches is covered either with thick crusts of a peculiar greyish-brown tint which display numerous superficial cracks, or parts normally free from hair exhibit shining epidermic crusts arranged in layers, which are shed on the slightest touch.

This depilation has a strong tendency to spread, and so at first it often resembles ringworm. It results from changes in the hair follicles, with atrophy of the papillæ and complete loss of hair. The changes in the skin, however, are little marked. The skin itself is but slightly thickened and preserves its usual suppleness, while the subcutaneous tissue is not œdematous.

The hairs, however, when examined microscopically are found to be thickened at their roots, though otherwise throughout their whole length they remain normal. The condition is a consequence of disturbance in the circulation and nutrition of the papilla and the root of the hair.

Finally, the congestive process extends to the sebaceous glands, the secretion of which it modifies, and sets up seborrhœa, which is responsible for the formation of the crusts and epidermic scales above-mentioned.

The pathogeny of the disease is difficult to explain, but the stages in the clinical development are as follows: the skin undergoes repeated attacks of congestion, followed by seborrhœic folliculitis, epidermitis and loss of hair.

=The diagnosis= is easy, the absence of ringworm being proved by the absence of the spores of trichophyton and by the non-contagious character of the discharge.

=The prognosis= is not grave from the point of view of general health, the chief functions being perfectly regular, but it is otherwise as regards possible terminations, viz., partial or total loss of the coat, which may be irremediable.

=Treatment.= It is difficult to lay down a really satisfactory method of treatment, because the exact cause of seborrhœa is still unknown. As it is probably to be sought in some individual constitutional peculiarity, the feeding and method of life should be changed and the skin stimulated by washing with lukewarm water and soap and by dry friction. Locally, if the alopecia threatens to be permanent stimulating applications may be tried. These comprise lotions containing alcohol, solutions of chloral, salicylate of soda, etc., and they should be applied with smart friction.

The sufferers should not be used for breeding purposes.

ECZEMA DUE TO FEEDING WITH POTATO PULP.

Among the forms of eczema due to toxins, several varieties may be recognised. Some result from the administration of drugs such as iodine, others from special forms of food. The only one of clinical importance is that following the consumption of excessive quantities of potato pulp.

=Causation.= The disease is seen in all districts in which potatoes are employed for the manufacture of alcohol and starch, more especially in Germany. The disease seems to be a direct consequence of feeding with residual products of distilleries and starch manufactories.

Spinola states that 160 lbs. of potato refuse per day to 1,000 lbs. of body weight would certainly produce eczema: 60 to 80 lbs. only produce it in rare cases and 20 to 40 lbs. are harmless.

There is a further point to consider as regards the variation of potato pulp in toxicity. Potatoes yield a more or less active residue, according to the year in which they are grown, their state of germination, and the variety to which they belong. Raw or cooked potatoes may produce eczema if given in large quantities or for long periods.

Numerous theories have been advanced as to the nature of the morbid disturbance producing eczema. Some authorities declare the appearance of the disease to be due to the presence of a toxic principle contained in potatoes, viz., solanin. It might be objected that this chemical principle only exists during germination while potatoes that have not undergone germination produce the disease. Further, the symptoms of poisoning by solanin differ from those of this form of eczema, among which loss of appetite, for instance, or stupefaction, or narcosis is never observable.

According to other writers eczema is due to the action of the lower alcohols contained in the refuse pulp, but again these properties exist in brewers’ and distillers’ grains, the consumption of which produces no bad results. Similar objections might be made regarding the suggested action of the acids of fermentation (lactic, butyric, and acetic acids, etc.).

Johne blames the salts of potassium, which, however, can only act as digestive irritants, and Zürn suggests mycosic inflammation.

Whatever the toxic principle, its effects are most marked in animals undergoing fattening, and are rarely found in working oxen, still more rarely in milch cows. In the last named the injurious principle appears to be eliminated in the milk, and this theory is supported by the fact that the liquid has purgative properties; the calves which consume it suffer from diarrhœa, which ceases when the feeding is altered.

Finally, it has been proved that different animals show different degrees of susceptibility to the action of potato pulp.

=The symptoms= do not appear until after two or three weeks’ feeding on the potato pulp. Then the animals walk stiffly, rise with difficulty, and display redness, swelling and sensitiveness of the limbs. When the œdematous infiltration and reddening have become distinctly marked there appear, not only between the claws, as in foot-and-mouth disease, but over the entire limb and principally near the folds of skin about the joints, numerous closely-packed small papules, which in one or two days become transformed into vesicles through exudation below the epidermis.

This marks the eczematous phase properly so called. The vesicles then become ruptured, the exuded matter glues the hairs together, dries, and forms crusts, which have a peculiar and distinctive odour.

The disease may extend towards the hocks, the knees, the stifle, the armpit, etc. In the folds of skin surrounding the joints deep cracks form, and sometimes become secondarily infected, thus leading to the development of lymphangitis.

General symptoms, such as fever, loss of appetite and constipation, always follow; they are afterwards succeeded by diarrhœa and progressive weakness, ending in death.

The disease is easily curable if seen in its earlier stages, but after all signs of the first attack have disappeared, the condition may return five or six times in a year if potato pulp is again given. Recovery is always very difficult in aged or enfeebled patients.

The mortality varies greatly; formerly it was as high as 20 per cent., but at the present time it is much lower.

=Diagnosis.= Provided the history of the case is borne in mind, the diagnosis is always easy.

=The prognosis= is not grave if the disease is treated early.

=Treatment.= This consists first of all in altering the diet and reducing the quantity of potato pulp, or, better still, in discontinuing it entirely. The food should consist of good hay, bran, oatmeal gruel, pollard, etc. Internally, diuretics are given to assist in the elimination of the toxic products.

This treatment arrests the course of the disease. Suitable local treatment will remove the existing lesions. It is precisely similar in character to that of acute eczema, but it must be borne in mind that it can only prove effective if the primary cause be removed.

IMPETIGO IN THE PIG.

The term impetigo is used to describe a disease characterised by an eruption of papules, the discharge from which forms yellowish crusts, which when dry are of a grey or brown colour. The point of origin of the eruption is unknown, but the crusts rapidly become infected on contact with the air, and the bodily lesions may end in suppuration. The disease is not frequent nowadays except in sucking pigs and in large or badly-kept piggeries.

=Symptoms.= The eruption usually appears between the ages of two and three months, and is accompanied from the first by moderate pruritus. The papules rupture after two or three days and discharge a lemon-coloured liquid, which is distributed over the surface, dries rapidly, and causes the bristles to stick together at the roots. The crusts formed in this way remain adherent to the skin, though their surface becomes cracked. They increase in thickness, cover the head and part of the body, particularly the belly and the inner surface of the thighs, and if removed, an operation of some difficulty, leave exposed a bleeding, sanious, or purulent wound. The animals lose condition and appetite, cease to grow, seem as though attacked with rachitis, and may die if the general conditions of their maintenance are not improved.

The =diagnosis= is not difficult, but the =prognosis= depends on how long the disease has existed and the bodily condition of the patients.

=The treatment= consists entirely in improving the hygienic conditions and the feeding. The patients must be repeatedly washed or bathed and carefully disinfected, and they must have better food.

The crusts should be softened before the animals are washed, so that bleeding may be avoided and the affected areas not be transformed into suppurating wounds. By applying oil or some fatty matter to the crusts it is possible to cleanse the parts with bran water. If considered necessary, this cleansing can be followed by dressing with boric or weak creolin solution. Open-air life and good food soon relieve the principal symptoms.

ACNE IN SHEEP.

Acne, that is to say, localised inflammation of the sebaceous glands and hair follicles, sometimes occurs in sheep apart from any parasitic invasion. The eruption is particularly seen after shearing, and it is probable that, as in the horse, irritation produced by the machine, and possibly by accidental infection, constitute the principal determining causes.

=Symptoms.= The disease is indicated by the appearance of cutaneous pustules, which are only slightly painful on pressure and which involve the entire thickness of the skin. The dermis is hardly congested, and no constitutional disturbance occurs.

Acne lesions may be more or less confluent, and may attain the size of a small hazel-nut.

=The diagnosis= presents no difficulty. Puncture or incision reveals the fact that the abscesses are filled with white sebaceous material and are quite free from parasites.

=The prognosis= is not grave. Recovery occurs spontaneously in a few weeks.

=Treatment.= Liquid emollient applications and the opening of the small follicular abscesses appear to represent the only means of hastening recovery.

FAGOPYRISM (BUCKWHEAT POISONING).

Fagopyrism is a disease of toxic origin in sheep, and is due to eating buckwheat (Polygonum fagopyrum).

The disease has also been entitled erysipelatous or gangrenous dermatitis, according to its form and gravity.

=Causation.= The cause is extremely simple, viz., the consumption of buckwheat and other food pertaining to a like species, such as Polygonum persicaria. The green plant and the straw give the same results, but the action of light and air are also necessary for the production of the disease, a fact which is somewhat difficult to explain.

According to German writers the disease occurs more frequently in white sheep and lambs than in those in which the skin is of a very dark colour.

=Symptoms.= When the sheep are fed in folds, with the green plant in summer or with the straw in winter, nothing unusual is seen, the herds being, to all appearance, in perfect health. On their being set at liberty, however, the first symptoms appear, perhaps in less than an hour. Some animals become restless, make peculiar movements of the head, and soon display intense congestion of the parts free of wool, together with redness and swelling of the ears, eyelids, face, throat, etc. The condition develops with extreme rapidity, the animals being immediately afflicted with pruritus over the affected regions. If they are not removed to the quiet and warmth of the fold the symptoms increase and papules appear, which may be transformed into vesicles and bullæ. In the fold, on the other hand, all the symptoms rapidly disappear.

The disease rarely assumes an erysipelatous form, but respiratory and cerebral symptoms, together with fever and vertigo, are not exceptional.

=Treatment.= The feeding on buckwheat should at once be discontinued, and the patients should be kept in the fold until the toxic principles have been eliminated, that is, for a month or more.

Bicarbonate of soda may be added to the drinking water. The local lesions about the head must be kept clean and dressed with antiseptic astringent lotions.