DEFORMITY AND STENOSIS OP THE TRACHEA. 445 



difficulty in swallowing and breathing, and the animal again became fit 

 for work. 



But such injuries cannot always be successfully treated ; de- 

 formities of the trachea sometimes result ; extensive wounds produce 

 stenosis of the trachea, accompanied by dyspnoea. Schwanefeld 

 describes a horse in which the trachea was flattened about the middle 

 of the neck and greatly narrowed. The presence of a stallion in 

 the stable excited it and induced suffocation. Some deformities 

 of the trachea are clearly congenital. Occasionally the posterior 

 ends of the tracheal rings are bent inwards, or flattened so that the 

 lumen forms merely a narrow fissure. 



Guilt saw a dog with marked flattening of the air tube. Harms and 

 Hagen note similar cases in cows. Johne describes two instances of 

 dilatation in horses, one about 24 inches in length, and a similar condition 

 was recorded by Bartenstein. Vegezzi found the dorsal surface of the air 

 tube of a horse presenting a furrow produced by bending inwards of the 

 ends of the cartilages and rupture of the inter-annular ligament. In this 

 furrow lay the (esophagus, carotid, vagus, and sympathetic. Eberbach 

 describes a horse in which dyspnoea was caused by compression of the 

 trachea, due to a large sarcoma (compression stenosis). 



The intact condition of the mucous membrane and the extension 

 of the change throughout the trachea shows the deformity to be 

 congenital. Compression, with narrowing of the trachea, may also 

 result from goitre, from enlargement of the bronchial glands, or 

 from tumour formation. Johne relates a case in a giraffe, and 

 Dietrich another in a foal which had died with symptoms of suffocation. 

 Between the first pair of ribs was a diseased gland, which had com- 

 pressed the trachea and caused suffocation. 



Cicatricial stenosis of the trachea is not an infrequent result of 

 'tracheotomy, especially in foals, or where the tube, worn for a long 

 period, does not fit well. Chronic perichondritis, resulting from the 

 continued irritation, induces formation of new fibrous tissue, which 

 sometimes ossifies, and narrows the lumen of the tube by contracting 

 around it. Thus Tiede found the trachea narrowed to the size of 

 a goose quill. Stricture is not always a result of unskilfulness in 

 performing tracheotomy or in selecting a tube, for stenosis sometimes 

 recurs in horses in which tracheotomy has been performed below 

 a previous stricture. 



The symptoms of injury to the trachea are difficulty in breathing, 

 and emphysema of the neck, with localised inflammation, swelling, 

 and pain. The degree to which the lumen of the tube is narrowed 

 in consequence of haemorrhage, dislocation of its cartilages, or 

 inflammatory swelling, determines the extent of the respiratory 



