This is more frequent in the horse than in other animals, and especially
so in young animals when newly stabled or put in training.
_Causes._ These are the same as those of _catarrh_ and _sore throat_. It
is but the continuation of the same mucous membrane which is affected in
all alike, and the same atmospheric changes, hot stables, noxious
inhalations and exposures to cold and wet will induce this disease
rather than the others when the bronchial mucous membrane is more
predisposed. Bronchitis often supervenes upon sore throat, by the
extension of the inflammation downward into the chest. Chilling of the
surface by exposure to cold, drenching rains, is a frequent cause, by
reason of the intimate sympathy existing between the skin and the mucous
membrane. For the same reason certain conditions of the skin will
predispose, thus a long, thick coat which keeps the animal constantly
drenched with sweat and the skin relaxed and sensitive. Williams draws
attention to the frequency and severity of bronchitis in both horses and
cattle conveyed by sea during stormy weather, and especially when the
hatches had to be fastened down. Such an experience combines in one the
evils of an overheated stall, a sudden transition often to extreme cold,
a lowering of the vitality of the whole system by the circulation of
non-ærated blood, a systemic poisoning by the retention of the waste
organic products that would otherwise have been eliminated, and the
special weakening of the lung tissue by congestion of the whole pulmonic
circulation.
But the development of bronchitis and broncho-pneumonia is the least
fatal result. The statistics of our European cattle traffic are rich in
the examples of absolute suffocation of cargoes in transit to Europe.
The following from Report of U. S. Treasury Cattle Commission is
illustrative:
“Dr. Thayer reports the case of a steamer from Boston to Liverpool, with
400 cattle on board, which encountered a storm and came through it with
only one animal surviving. Mr. Toffey, of Jersey City, lost 30 head out
of a cargo of 300 by suffocation in 1880. This happened, he informs us,
on a calm sea on a southern route with a temperature about 90° F., and
the wind astern and light so as just to keep pace with the ship. The air
on board the ship became perfectly stagnant, and there was no means of
establishing an artificial current. A still more disastrous experience
befell the steamer Thanemore, Captain Sibthorp, of the William Johnson &
Co. line. This vessel left Baltimore with 565 cattle on board, of which
228 perished by suffocation before she reached Cape Henry.”
Among animals that survive such treatment the susceptibility to lung
disease including even the contagious forms like tuberculosis is
enormously enhanced.