482 DISEASES OF THE BRONCHI. 



II. Chronic Bronchitis. 



Nature and Causation. — This condition of chronic bronchial 

 catarrh we meet with in the horse less frequently than m 

 some other of our patients. In him it appears occasionally 

 both as a sequel of acute bronchitis and as an independent 

 affection. It differs from any of the manifestations of the 

 acute by the absence of fever, and the persistence of a hard, 

 sonorous, troublesome cough ; while the discharged or ex- 

 pectorated material is rarely of the viscid, tenacious, cellular 

 nature of acute bronchial inflammation. 



When the result of acute bronchitis, the chronic form is 

 more usually attended with defective respiration when the 

 animal is put to rapid movement, than when developing as an 

 independent diseased condition. 



From the manner in which the symptoms seem to be sus- 

 ceptible of aggravation, the cough and dyspnoea would appear 

 to be largely dependent on constriction of the smaller bronchi, 

 either from partial occlusion, the result of thickening of the 

 lining membrane, or from irregular spasm of the encircling 

 fibres. In isolated instances chronic bronchitis may continue 

 for some time, and at last, on the occurrence of a very 

 trivial cause, terminate in a rather smart attack of the acute 

 form, from which, when the animal recovers, the original 

 chronic bronchial irritation and paroxysmal cough remain. 

 Many cases in horses spoken of as chronic cough, if examined 

 carefully, wiU be found associated with some little difficulty in 

 breathing and impediment in the process of respiration, and 

 are apparently true instances of mild chronic bronchitis. 

 Although fever may not be present in chronic bronchial 

 inflammations, and, with the exception of the local s}Tiiptoms 

 of cough and impeded respiration, the horse may show no 

 indications of ill-health, we yet find, in numerous instances 

 where this condition is of any time standing, that a steady 

 loss of flesh is not uncommon even when the appetite con- 

 tinues good. 



Symptoms. — On making examination of the respiratory 

 organs of such animals as are sufferers from chronic bronchitis, 

 auscultation may satisfy us that, although somewhat similar 

 to acute bronchitis, the lesions are not of precisely the same 



