DISEASES OF THE RESPIRATORY SYSTEM. 95 



parasites. It is clear there is nothing diagnostic about 

 the symptoms recorded, although possibly microscopical 

 examination of expectorated matter would elucidate the 

 cause of the pneumonic attack. 



Treatment should be chlorine inhalations and stimulant 

 tonics, such measures as are resorted to for cases of hoose 

 in young cattle, an exact pathological equivalent of the 

 disease under consideration. Therefore the intratracheal 

 method of administration might be tried. 



Asthma — Chronic Bronchitis — is, in the main, a disease 

 of senility, and pathologically resembles the diseases of 

 nostril and larynx already described as ozsena and chronic 

 cough. Differences between these three diseases result 

 from the structure and situation of the membrane involved. 

 In each, however, atony is the primary element. The 

 smaller bronchial tubes in the lungs have a well-developed 

 muscular layer, which, with the mucous coat, becomes 

 involved in true asthma and undergoes degenerative 

 changes. The muscular tissue in the earliest stages is 

 affected with spasm, and the mucous layef with chronic 

 congestion. Later the mucous coat becomes thickened, 

 and the fibres, often muscular, undergo fatty degeneration. 

 The air passages become blocked up, and thus access of 

 air to particular parts of the lung prevented ; emphysema, 

 true or false, then affects more or less of the rest of the 

 lung. It is a mistake to draw a line, as some have done, 

 between congestive and spasmodic asthma ; both these 

 conditions are present in all cases of the affection ; at 

 times the paroxysmal spasm proves so urgent as to mask 

 the by no means less serious indications of congestion, and 

 in others there is scarcely any indication of spasm. This 

 disease is rarely fatal, although it causes extreme distress 

 at times. 



Causes. — Pets of fancy breeds, house and watch dogs, 

 are most frequently the subjects of this disorder, because 

 they have the fewest opportunities for exercise, they are 

 generally highly fed, least inclined to exertion, and most 

 liable to indigestion, Over-feeding, pampering in other 

 ways, extreme obesity and want of sufficient exercise, are 



