coo SPORADIC DISEASES. 



white to a yellow or yello wish- brown. If an animal be exa- 

 mined post mortem, after the disease has existed for four or five 

 days, the windpipe and larynx will be lined for a considerable 

 distance, in some places partially only ; in other parts the entire 

 circumference will be embraced by the false membrane, forming 

 a complete hollow tube or cylinder. 



Some writers maintain that croupous inflammation is a more 

 intense form of inflammatory action than that witnessed in 

 ordinary (catarrhal) inflammation of mucous membranes. Dr. 

 Copland, however, states that subacute or slight inflammatory 

 action may be inferred as having existed in connection with an 

 increased proportion of fibro-albuminous matter in the blood, 

 whenever we find the croupal productions in the air passages. 

 Neither of these views seems to account for the peculiarity of 

 croupous inflammation, and I do not think that it is due to 

 any specific cause. Indeed, direct experiment has shown that 

 severe irritants induce the formation of false membrane on 

 mucous surfaces ; and we must rest content with the conclusion 

 that in young animals growth is rapid, and that the new forma- 

 tion is so rapid in growth, and so plastic in consistence, as to 

 remain more or less firmly adherent to the structure from which 

 it is developed. 



The causes, as already indicated, are damp and cold, particu- 

 larly exposure to heavy dews at night. 



Symptoms. — These generally commence M'ith a hoarse cough, 

 discharge of frothy saliva from the mouth, and of mucus from the 

 nose ; the animal is unthrifty, has some difficulty in swallowing; 

 sometimes swellings appear in the parotid and submaxillary 

 regions, succeeded by difficulty in breathing, the inspiratory act 

 being accompanied by a crowing noise, and by spasm of the 

 laryngeal muscles, causing violent paroxysms. In other cases 

 the spasmodic affection of the larynx and difiicult breathing 

 may occur without any premonitory warning. The pulse, hard 

 and quick at the commencement, becomes feeble and indistinct 

 as the disease advances, the fits of coughing more and more 

 troublesome and violent; paroxysms constantly occur, particu- 

 larly if the animal be subjected to any sudden excitement. In 

 the course of two or three days flakes of the non-vascular 

 and unorganised false membrane are coughed up ; the expecto- 

 ration becomes more profuse ; being loosened and detached by 



