210 CHAPTEi; 22. 



BRONCHITIS. 



428. Xature, seat, ami causes. 



Bronchitis consists in inflammation of the Bronchial tubes. There are 

 two fomis of the disease, namely inflammation of the larger tubes, and 

 2ndlv inflammation of the smaller tubes, called capillary bronchitis. The 

 latter attack is far the more dangerous, because the inflamed and 

 thickened state of the membrane of the minute tubes or the increased 

 secretion of mucus in them prevents the blood from being properly 



aerated. 



Bronchitis usuallv commences with slight catarrh and cough, and the 

 horse is oS his feed and a little feverish. At other times there are no 

 catarrhal svmptoms. and the only noticeable sign is feverishness and 

 quickened breathing. This state of the breathing, if not carefully looked 

 for, mav easilv escape observation. Hence grooms so often declare that 

 the breathing "is perfectly regular, whilst the practised eye of a man. who 

 is accustomed to observe', sees at once the mischie! which is going on. 



The first positive sign of Bronchitis is indicated by quickened breath- 

 ing, accompanied with a slight whistling or hissing sound heard on 

 auscultation at the sides of the chest, or else by a deeper and more 

 noisy sound in front of the chest. The whistling sound is technically 

 known as Sibilus, and marks inflammation of the smaller tubes ; whilst 

 the deeper sound, which is known as Rhonchus, indicates inflammation 

 of the larger tubes. The peculiarity of these sounds arises from the 

 passage of^the air over a dry inflamed membrane in the tubes. During 

 this, or the - dry stage," the pulse is harder and quicker than natural, 

 and' as the disease progresses it becomes quicker and smaller, until in 

 very bad cases it can be no longer felt. The breathing is also much 

 quickened, and the membrane of the nostril is red and inflamed. 



About the second day the dry state of the bronchial memlirane is 

 succeeded by a moist state, with an increa.sed secretion of mucus accom- 

 panied with a suppressed cough. This change, though it has no par- 

 tic\ilar sienificance, is yet often indicative of relief, inasmuch as it shows 

 that one stage of the inflammation has passed. It is the result of the 

 effusion, which always (except when the attack ends in resolution) takes 

 place in inflammatory attacks when the blood-vessels of a part have 

 become overloaded and over-distended. (See Chapter 18 on Inflamma- 

 tion.) The pulse, which during the dry stage had been harder and 

 quicker than natural, now becomes decreased in volume and increased in 

 frequency. Should the Schneiderian membrane, which had been red 

 and inflamed, become moist, and at the same time the secretion from it 

 of a more natural character, it is a very favorable symptom. 



If the mucus which is now secreted is not freely expectorated, it will 

 accumulate either in the larger or smaller tubes, according to the locale 

 of the attack. In the larger tubes it affords considerable impediment to 

 the respiration. The sound of the air passing through them is known as 



