DISEASES OP THE RESPIRATORY SYSTEM. &3 



the main passage for air expired or inspired in the dog. 

 In the emergencies of respiratory disease and extreme 

 exertion it is kept open and the tongue protruded ; the 

 velum pendulum palati is short and so allows free respira- 

 tion through the mouth. Indeed, for respiratory purposes 

 we must consider that the nasal passages have only an 

 everyday function ; they become quite subordinate in 

 emergencies. They are, in some breeds, however, very 

 important organs of smell, but from a respiratory point of 

 view will bear no comparison with the wide, complex, 

 highly vascular, air- warming passages seen in herbivora. 

 This adaptation of the mouth to passage of air as well as 

 food is possible in carnivora, because in them the food is 

 rapidly passed through the mouth and feeding takes a very 

 short time, whereas the mouth of herbivora is generally 

 filled with food and its passage occluded in the act of 

 mastication or remastication. These details are necessary 

 in order that we may understand why diseases of the 

 nostrils and their accessories are of so little importance 

 and so infrequent in the dog as compared with the horse. 



Catarrh or Cortza, which is congestion, running on to 

 inflammation, of the lining membrane of the nasal cham- 

 bers, is somewhat frequent. It results from exposure to 

 draughts, severe weather, east winds, and especially when 

 the dog has been used to warm, close quarters. 



The symptoms are fever, more or less severe, discharge 

 from the nostrils, at first watery, later mucous, and then 

 becoming intermingled with pus. The animal snorts out 

 the discharge frequently and snuffles in breathing. The 

 eyes generally water through sympathy or the excess of 

 tears flows through the ductus ad nasum ; persistent 

 sneezing and an occasional cough are present. The dis- 

 ease is liable to extend and involve the pharynx and larynx. 

 When the sinuses are invaded the animal is very dull and 

 " snuffles " a good deal. Difficulty in swallowing and 

 tingeing of the nasal discharge with the liquids of the food, 

 also severe cough, show that the throat is becoming in- 

 volved. 



As treatment simple nursing generally suffices, but in 



