DISEASES OF THE AIR-PASSAGES OF HORSES. 225 
from November to April. The exciting causes I consider are, 
commonly, cold and moisture, and such other states of the atmo¬ 
sphere as check the insensible perspiration, and alter the func¬ 
tions of such parts of the mucous tissue most obnoxious to their 
first impression. There can be no question of the state of the air 
at certain periods influencing the prevalence of catarrhal disorders; 
but much is depending on the condition of the system to render 
such impressions capable of producing disease. Moving horses 
from one locality to another will sometimes produce colds and 
coughs, and at others remove such ailments. Another cause of in-, 
flammation of the respiratory mucous surface is the continuance of 
travelling with a cold wind in the face; the sudden change from a 
low to a high temperature, particularly following a long exposure 
to a cold moist atmosphere, or the exposure to wet for some time 
of such horses as are stabled. Cynanche trachealis generally arises 
from extension of inflammation either from the larynx or bronchi, 
and I therefore direct my observations to the principal part of my 
subject. Bronchitis. 
Inflammation of the bronchial surface, as a distinct disease, has 
not had that particular attention by authors and systematic writers 
so important a disorder requires, but has been confounded with 
catarrh and the diseases of the lungs. However, I presume there 
are few practitioners of experience but are by this time satisfied 
that bronchitis is a distinct disease, and by no means of unfrequent 
occurrence. Inflammation of this part of the mucous surface of 
air-tube arises variously, and presents different grades of intensity, 
according to »the severity of the exciting causes and the state of 
the animal at the time of attack. It is very prevalent during some 
seasons, and frequently fatal. Acute bronchitis, in its sthenic or 
true form, is sometimes preceded by a soreness of throat and cough; 
a sense of soreness in the larynx, evidenced by coughing after water 
and food is swallowed ; and by external compression. As the sore¬ 
ness of throat diminishes, the inflammatory action advances along 
the mucous tissue of the trachea to the bronchi. But without this 
precedence of morbid action, it commences in the latter situation, and 
assumes a severe form: marked chills, with a death-like coldness of 
the nose, ears, and legs, precede the attack, or a complete rigor before 
or early in the commencement of the ailment. The cold fit is soon 
followed by a general warmth, a quick pulse, increased respiration, 
and oppression at the chest, painful cough or sneeze, eyes injected, 
loss of appetite, and considerable prostration of strength. The fre¬ 
quency of the pulse, respiration, and cough, increase as the disease 
proceeds, and a secretion of mucus in the bronchi comes on : the 
oppression and anxiety of countenance is more marked. The 
bronchial murmur, which at first is sonorous or wheezing, becomes 
