SOCIETY MEETINGS. 
137 
muscular fibres of the bronchial tubes, giving rise to paroxysms 
of dyspnoea, which are due to reflex nervous action. It is a non- 
imflaminatory disease, and may be regarded as a neurosis depend¬ 
ing upon a peculiar diathesis. The dyspnoea may be constant, with 
exacerbations and remissions at times, and the paroxysms may or 
may not be accompanied by catarrhal symptoms; if these occur, 
they may either precede or follow the attack, yet this disease is 
strictly non-imflammatory. An inflammatory condition of the 
mucous membrane of the bronchial tubes certainly acts as an ex¬ 
citing cause; this is of itself an irritation which gives rise to re¬ 
flex tonic spasms, but a peculiar condition of the nervous system 
must exist, otherwise the paroxysms would not be produced. In 
animals suffering from organic disease of the heart or lungs, it is 
likely to arise. Asthma and pulmonary emphysema have been 
confounded and considered by some veterinarians as one and the 
same disease ; although very frequently associated, they are dis¬ 
tinct affections, and each may exist independently. It is a neuro¬ 
pathic affection, and no appi'Cciable lesion is found on post-mor¬ 
tem to indicate its presence, and has no anatomical characteris¬ 
tics. Co-existing, as it may, with bronchitis and pulmonary em¬ 
physema during life, the lesion which tells of their having been 
present only arc appreciable. 
Etiology .—Its causes may be divided into predisposing and ex¬ 
citing. The predisposing cause is due to some peculiar suscepti¬ 
bility or constitutional diathesis, which is generally hereditary and 
transmitted from an animal to its offspring, and this may manifest 
itself at any period of life. It may also be acquired, and the ani¬ 
mal acquiring it transmits to its offspring. The exciting causes are 
various. It may be produced by irritants directly to the bronchial 
mucous membrane, or from some reflex origin situated in distant 
parts, and again it may occur as a complication of some other dis¬ 
ease. It originates from inhalations of smoke, irritating gases, 
emanations of hay, etc. Noxious substances present in certain 
atmospheric conditions excite it. I recall an instance where a 
gentleman demonstrated beyond a doubt, that in an animal of his 
it was caused by inhaling fumes of sulphur ; for so soon as the 
animal was led into a barn where sulphur had been burned, itim- 
