101 



treatment recommended is : Give a pint of linseed oil and after it has 

 operated administers drams of bromide of potassium three times a day, 

 dissolved in the drinking water, or give as a drench in about a half 

 pint of water, for a week. Then give a dram of powdered nux vomica 

 (either on the food or skaken with water as a drench) once a day for 

 a few weeks. 



CROUP AND DIPHTHERIA. 



Both of these diseases, it is claimed, aflfecfc the horse. But such 

 cases must be rare, as veterinarians of extended experience have failed 

 to recognize a single case in their practice. The symptoms are so much 

 like those of inflammation of the larynx that it would be imjjossible 

 for the general reader to discriminate between them. 



ROARING. 



Horses that are affected with a chronic disease that causes a loud 

 unnatural noise in breathing are called " roarers." This class does not 

 include those affected with severe sore throat, as in these cases the 

 breathing is noisy only during the attack of the acute disease. 



Eoaring is caused by an obstruction to the free passage of the air in 

 some part of the respiratory tract. Nasal polypi, thickening of the 

 membrane, pharyngeal polypi, deformed bones, paralysis of the wing 

 of the nostril, etc., are occasional causes. The noisy breathing of horses 

 after having been idle and put to sudden exertion is not due to any dis- 

 ease, and is only temporary. Very often a nervous, excitable horse will 

 make a noise for a short time when started off, generally caused by the 

 cramped position in which the head and neck are forced, in order to hold 

 him back. 



Many other causes may occasion temporary, intermitting or perma- 

 nent noisy respiration, but after all other causes are enumerated it will 

 be found that more than nine out of ten cases of chronic roaring are 

 caused by paralysis of the muscles of the larynx ; and almost invariably 

 it is the muscles of the left side of the larynx that are affected. 



In chronic roaring the noise is made when the air is drawn into the . 

 lungs; and only when the disease is far advanced is a sound i)roduced 

 when the air is expelled, and even then it is not near so loud as during 

 inspiration. 



In a normal condition the muscles dilate the aperture of the larynx 

 by moving outward the cartilage and vocal cord, allowing a sufficient 

 volume of air to rush through. But when the muscles are paralyzed, 

 the cartilage and vocal cord that are normally controlled by the af- 

 fected muscles remain stationary ; therefore when the air rushes in it 

 meets this obstruction, and the noise is produced. When the air is ex- 

 pelled from the lungs its very force pushes the cartilage and vocal cords 

 out, and consequently noise is not always produced in the expiratory 

 act. 



