440 DISEASES OF THE LARYNX AND TRACHEA. 



dimensions before marked symptoms appear ; but difficulty both of 

 breathing and swallowing are then noted. As in diseases of the 

 tongue, and in the so-called pharyngeal lymphoma, dyspnoea may 

 occur, particularly during feeding. The disturbed respiration and 

 deglutition are not uniform in their appearance, as Fricker and Dieck 

 have noted in horses. Pedunculated tumours at the base of the 

 tongue, dropping on to the larynx, may suddenly produce symptoms 

 of severe inspiratory dyspnoea, causing the animals to fall and occa- 

 sionally to die of asphyxia. The sudden appearance of dyspnoea, 

 without febrile or other constitutional disturbance, denotes the 

 presence of such tumours. The condition may be easily mistaken 

 for oedema of the glottis. 



The exterior of the larynx is seldom visibly altered. Only where 

 the new growth has spread to the exterior, or has produced marked 

 changes in the wall of the trachea, does the region of the larynx 

 appear fuller and swelling show itself. Prietsch also observed this 

 in cows which suffered from laryngeal tuberculosis. 



Examination through the mouth often gives more definite 

 information. In carnivora, by drawing forward the tongue with a 

 cloth and pressing down its base with a spatula it is possible to view 

 the interior of the larynx and determine the presence of tumours 

 on its upper borders. In horses this may be effected with the 

 laryngoscope constructed by Polansky and Schindelka. When this 

 instrument is not available, the pharynx may sometimes be examined 

 when the horse is cast, provided the position of the molars and the 

 soft palate allow the passage of the hand. Such examination is 

 more easy in oxen, and, if the head is fixed, may be made while the 

 animal is standing. 



In doubtful cases the larynx can be opened and a view of its 

 interior obtained, an operation entirely without danger, and to be 

 resorted to whenever it is important positively to ascertain whether 

 or not disease exists within the tube. 



Tumours in the trachea are first remarked when they narrow 

 the lumen of the tube considerably, and produce dyspnoea. This 

 is generally accompanied by loud breathing sounds, which occur 

 both during inspiration and expiration, though occasionally only 

 during expiration. It is characteristic of tumours in the trachea 

 that the noise appears especially during expiration. The position 

 and nature of the new growth explain this peculiarity. Dyspnoea 

 increases with the growth of the swelling, and may terminate in 

 suffocation. Only where malignant tumours perforate the wall of 

 the trachea and extend outwards can their presence be directly 



