133 



affection of the muscles leads to a paralysis of them, ana is considered 

 one of the primary stages of broken wind. 



Some eminent veterinarians maintain that the exciting cause of 

 broken ^rind is due to a lesion of the i^neumogastric nerve. That there 

 is good foundation for this opinion there can be no doubt. The pneu- 

 mogastric nerves send branches to the bronchial tubes, lungs, heart, 

 stomach, etc. All the organs just mentioned may sooner or later be- 

 come involved in connection with broken wind. It may be said that 

 broken wind is always associated with disorder of the function of 

 digestion. It is claimed that coarse or indigestible food irritates the 

 branches of the pneumogastric nerves which supply the walls of the 

 stomach, and this irritation is reflected or extended to the branches 

 of the same nerve which sujjply the lungs, when the lesions consti- 

 tuting broken wind follow. 



In itself broken wind is not a fatal disease, but death is generally 

 caused by an affection closely connected with it. After death, if the 

 organs are examined, the lesions found depend much upon the length 

 of time broken wind has affected the animal. In recent cases very 

 few changes are noticeable, but in animals that have been broken- 

 winded for a long time the changes are well marked. The lungs are 

 paler than natural, and of much less weight in x^roportion to the vol- 

 ume, as evidenced by floating them in water. The walls of the small 

 bronchial tubes and the membrane of the larger tubes are thickened. 

 The right side of the heart is enlarged and its cavities dilated. The 

 stomach is enlarged and its walls stretched. And in many old cases 

 the intestinal walls undergo the same changes. The important change 

 found in the lungs is a condition technically called pulmonary emphy- 

 sema. This is of two varieties: First, what is termed vesicular 

 emphysema, which consists of an enlargement of the capacity of the 

 air-cells (air vesicles) by dilation of their walls ; the Avails after a time 

 degenerate, and finally give way, and thus form a communication 

 with other air-cells. The second form is called interlobular emphy- 

 sema, and follows the first. In this variety the air finds its way into 

 the lung tissue between the air-cells, or, as its name indicates, in the 

 tissue between the small lobules. 



Symptoms. — Almost every experienced horseman is able to detect 

 "heaves." The peculiar movement of the flanks and abdomen point 

 out the ailment at once. But in recent cases the affected animal does 

 not always exhibit the characteristic breathing unless exerted to a 

 certain extent. The cough which accompanies this disease is peculiar 

 to it. It is difficult to describe, but the sound is short, and something 

 like a grunt. 



When air is inspired, that is, taken in, it ai)i)ears to be done in the 

 same manner as in health; it maj" possibly be done a little quicker 

 than natural, but not enough to attract anj' notice. It is when the 

 act of expiration (or expelling the air from the lungs) is perfoi'med 



