Chronic pleurisy occasionally follows the acute form of the disease, hut in the majority of cases is a sub-acute affection from the first. It is often developed imperceptibly, those prominent symptoms observed in the acute form, being absent or lacking sufficient intensity to characterize the disease.

Anatomically, the conditions existing in chronic pleurisy are essentially the same as in the acute form. The pleural cavity contains a liquid effusion of serum and lymph, which in the event of recovery becomes absorbed. Bands of adhesion are formed uniting the inner surface of the pleura, and the chest walls become contracted, leaving a depression generally permanent, more especially in cases of large effusions.

Causation

The same influences may give rise to chronic that are involved in the causation of acute pleurisy. It may be induced traumati-cally, and is sometimes due to exposure. More often it proceeds from internal causes which are not understood.

Symptoms

Cough, pain and tenderness are frequently wanting, and rarely prominent in this disease. The most marked symptom is the increased frequency of the respirations, which may be moderate while at rest, but become evident on exercise. Here, as in the acute form, the embarrassment in breathing will depend upon the amount and rapidity with which the effusion takes place. The pulse generally runs above the normal, and is small and compressible. Appetite is impaired.

Diarrhoea occurs in some cases, and emaciation may follow, although the strength is often maintained to a marked degree, and the animal be out and take considerable easy exercise.

Diagnosis

The symptoms apparent in this disease will aid much, but a positive diagnosis can hardly be reached without auscultation and percussion. The signs of liquid effusion are the same in chronic as in acute pleurisy. In the former the amount is often greater, and the contraction of the affected side is more marked after absorption.

Chronic pleurisy is often associated with other diseases, among them pulmonary consumption and dropsical affections, which, by their individual symptoms, may be detected.

Prognosis

Simple chronic pleurisy unassociated with any other serious disease, and occurring in an animal previously healthy, may be recovered from, but a permanent deformity, in contraction of the affected side is quite certain to result. Death often occurs from associated complications. In many cases a breaking down of the lungs follows chronic pleurisy, and the disease assumes the form of consumption. In other cases absorption of the effusion may go on to a certain extent, and the animal regain good Health, even although a portion of the liquid remains.

Chronic pleurisy may end in empyema, in which disease the liquid becomes purulent, and from which recovery is very doubtful.

Treatment

The objects of treatment are to remove the effused liquid, and develop and sustain the general strength of the system. For the first object, the measures which may be employed, are the same as in the last stage of acute pleurisy. Small blisters, or the tincture of iodine may be applied to the affected side, and mild laxatives should be judiciously given if the general condition and strength warrant their use.

The second object calls for tonic remedies, which should be given three times a day. A pill, combining several of the more powerful agents, can be made as follows -

℞ Quiniae Sulph. gr. xxiv.

Ferri Carb. ℥ ss.

Ext. Nucis Vomicae gr. viij Ft. Pil. No. xxiv. Sig. Dose one three times daily.

Tonics should be persisted in, and may be changed occasionally, as the animal becomes accustomed to their use. The pills may, after a time, be discontinued, and the syrup of the iodide of iron in ten drop doses, or the elixir of calisaya bark, iron, and strychnia in teaspoonful doses, be given. If the animal be thin in flesh, cod liver oil must be added to the treatment.

Pure air, gentle exercise, and nutritious diet are essential in this, as in all exhausting diseases.

In extreme oases, where a rapid formation of the liquid effusion threat-ens death by suffocation, tapping the chest may be resorted to, but a skilful physician, the family attendant, should be employed for the operation, which, in but few cases, will result unsuccessfully, as the fluid generally returns.