Symptoms. Tuberculosis is the most protean of all diseases, and at first sight it often seems impossible to assign to one group, clinical conditions presenting such essentially different appearances. All the tissues may be attacked, from the bones to the most delicate of the viscera, a fact which explains why all aspects of tuberculosis cannot be described. Certain forms, however, occur very frequently, and may be regarded as classic; these will be considered in the order of their frequency.
TUBERCULOSIS OF THE RESPIRATORY APPARATUS.
Without doubt this form of tuberculosis is by far the most frequent. It assumes the form either of bronchitis, laryngo-bronchitis, or pulmonary tuberculosis.
Tuberculous Bronchitis.—The symptoms of tuberculous bronchitis do not essentially differ from those of ordinary bronchitis, though the disease develops more insidiously and slowly, and is seldom accompanied by fever. At first the cough is dry and suppressed; later it becomes paroxysmal, and at a still more advanced period liquid and rough. The least irritation brings on these attacks of coughing; changes from the warmth of the stable to the coldness of the outer air or vice versâ, the presence of dust or the action of liquids when drinking, etc., etc. During the first stage coughing is not followed by expectoration, but later yellowish-grey, glairy mucus may be discharged: more frequently it is coughed into the pharynx and swallowed.
These symptoms continue for weeks or months without showing any tendency to abate. If the larynx is attacked inspiration becomes rattling and difficult, while the neck and head are held extended, and the least pressure over the larynx produces coughing.
Tuberculosis of the larynx, trachea, and bronchi is usually accompanied by disease of the lung, but may occur by itself.
When there is a discharge it consists of thick, viscous, sticky mucus of a peculiar greyish-yellow colour. Microscopical examination shows it to contain tuberculous bacilli.
Pulmonary Tuberculosis usually assumes the chronic form, and is almost always preceded by specific bronchitis. The patients retain their appearance and condition for a longer or shorter time, and, without the experience resulting from continued observation, it would be difficult to believe them to be suffering from the slow development of a serious disease.
Frequent coughing without any apparent reason is the only symptom likely to arouse suspicion.
At a later stage these animals lose condition, feed less eagerly or exhibit capricious appetite, and sometimes well-marked and repeated digestive disturbance, such as slight tympanites with constipation or diarrhœa, moderate impaction of the rumen, relative atony and slackening of peristaltic movements. The wasting gradually becomes more marked or, in the case of pregnant or milch cows, makes intermittent progress, until the animals become anæmic and finally cachectic. The cough is more frequent and more severe, and is followed by discharge from the nose or by swallowing movements. From this time phthisis, properly so called, exists.