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miU called aoari, which breeds and burrows in the skin. To curt 

 mange, destroy the insect. (See Skin Diseases.) 



Materia Medica. — This is a name applied to every substance 

 used in the treatment and cure of disease. 



Megrims. — A disease of the brain occurring at periods, es- 

 pecially in hot weather, and when exposed to a powerful sun. 

 This differs from epilepsy only in the absence of spasms. (See 

 Epilepsy.) 



Causes, Tumors in the choroid plexus and enlargement of the 

 pineal gland. 



Treatment. Merely palliative, by using a Dutch collar, so as not 

 to interfere with the circulation of the blood from the head. 



Observe. In summer the horses subject to brain disease, or fits 

 of any kind, should not be used for family purposes. In winter 

 they will make useful animals. 



Melanosis. — A variety of cancer peculiar to gray horses, which 

 turns white with age, and is caused by the transfer of the coloring 

 pigment from the skin to the blood. (See Cancer.) 



Melanoid. — (See Cancer and Tumors.) 



Mesentery. — A membrane formed of two folds of the peri- 

 toneum, between each of which there are numerous glands, lac- 

 teals, lymphatics, arteries, veins and nerves. It is called the 

 mesentery, because it adheres to three lumbar vertebrfe, and has 

 the small intestines hanging to it. One portion of it is called the 

 mescolon — supporter of the colon — and another the mesorectum, 

 which encloses the rectum. 



Mesenterica. — Wasting of the mesentery is a disease which is 

 not very common to horses, although sonae clearly marked cases 

 are sometimes seen, characterized by wasting of the body, weak- 

 ness, and general debility of the whole system. Bowels irregular, 

 sometimes soft, at other times hard, of a pale or straw color, and 

 frequently of bad smell. All that can be done is to keep the 

 strength and condition of the horse up by iron and gentian, so 

 frequently recommended throughout the book. 



Metastasis. — A term denoting a change or shifting of disease 

 from one part of :he body to another, as is well illustrated in caaea 

 of rheumatism. 



Moon Blindness. — (See Eye Diseases.) 



