CHRONIC LARYNGITIS AND PERI LARYNGITIS. 
185 
and swelling show itself. Prietsch also observed this in cows which 
suffered from laryngeal tuberculosis. 
Examination through the mouth often gives more definite informa¬ 
tion. In carnivora, by drawing forward the tongue with a cloth, 
and pressing down its base with a pair of scissors or the handle of a 
spoon, it is possible to view the interior of the larynx and deteimine 
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 made use of 
wherever it is important to remove doubts. 
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 inspir¬ 
ation and expiration, though occasionally only during one portion of the 
act. It is characteristic of tumours in the trachea that the noise appears 
especially or exclusively 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 extern 
outwards can their presence be directly recognised. Diagnosis is rarely 
aided by palpation of the trachea; but pressure on the diseased spot 
may, perhaps, increase or decrease the dyspnoea. 
Prognosis is in general unfavourable. Pus formation and the discharge 
of abscesses into the trachea may occasion pneumonia. In chronic 
laryngitis with thickening of the mucous membrane, resection of the 
vocal cords may be serviceable. Prognosis of perilaryngitis fibrosa, 
and other diseases, depends in great part on the degree of dyspnoea 
. Tracheotomy is certainly a palliative. The prognosis of most laryngeal 
tumours is unfavourable ; but pedunculated growths, situated even m the 
larynx, may sometimes be removed without recurrence, section being 
made of the cricoid cartilage and first rings of the trachea. Where the 
operation is unsuccessful, tracheotomy will still render the animals 
workable for some time. 
Treatment. Tumours on the epiglottis can sometimes be removed in 
the same way as pharyngeal tumours (p. 179) m cattle, by tearing them 
away with the hand ; in dogs, with the assistance of instruments. Dieck 
removed a swelling as large as a hen’s egg from the epiglottis of a horse 
