192 TNORGANIC AGENTS 



iodide has given good results in the treatment of periodic ophthalmia in 

 horses with the first attack. They are given one ounce daily for two or 

 three days, and kept in the dark with cold compresses over the eyes. 

 Potassium iodide has a clinical reputation for its power to aid absorption 

 and resolution in inflammation or effusions of the brain or cord, in hemi- 

 plegia, paraplegia and meningitis 



Summary. — Iodine and, potassium iodide resemble one another in 

 many respects. Iodine is a local irritant, potassium iodide is not. The 

 known physiological action of potassium iodide and iodine does not explain 

 their medicinal uses. In combating certain diseases, in an inexplicable 

 manner, they are known as alteratives. In man, iodine is superior to 

 potassium iodide in the treatment of scrofula. In the horse, iodine is 

 considered of more value in the treatment of diabetes insipidus ; while in 

 both man and the lower animals, potassium iodide is regarded as more 

 valuable in chronic rheumatism. In subacute rheumatism, one prescribes 

 equal parts of sodium salicylate and iodide. The action of iodine in ben- 

 efiting local disorders, when applied externally, is due to its counter 

 irritant effect, rather than to absorption. 



Administration. — Potassium iodide is given in solution. Sodium 

 iodide and syrup of hydriodic acid are simply substitutes for potassium 

 iodide. 



THYBOiDEnM SiccuM. Dried Thyroids. (U. S. P.) 



Synonym. — GlanduliE Thyroideae siccae. 



Dose. — Dogs, gr.%-ii, (.03-.12), twice daily, on food or in capsules. 



The thyroid glands of animals which are used for food by man, 

 freed from connective tissue and fat, dried and powdered and containing 

 not less than 0.]7, nor more than 0.23 per cent of iodine. A yellowish, 

 amojphous powder, having a slight characteristic odor, and containing 

 the active ingredient of thyroid tissue; partially soluble in water. One 

 part of the dried glands represents approximately 5 parts of the fresh 

 glands. As the therapeutic activity of the glands depends chiefly upon 

 their iodine content a standard of not less than 0.2 per cent of iodine 

 has been adopted for commercial preparations. 



Action. — A condition of cachexia in which the cutaneous tissues swell 

 and other abnormalities occur (myxedema), after total removal of the 

 thyroid gland, was found to be overcome by feeding thyroid tissue. 

 Likewise the same condition occurring spontaneously in the human adult 

 and cretinism in children, from absence of thyroid tissue, are cured by 

 administration of thyroid gland. This was the beginning of the thera- 

 peutic use of the thyroids. It was later discovered that iodine is the 

 main inorganic constituent of the thyroid gland and that its functional 

 activity depends largely upon this element. Nevertheless it is true that 

 individual persons and animals may possess thyroid glands wholly want- 

 ing in iodine without any interference with health. When the thyroid is 

 removed from such individuals the same severe symptoms occur as are 

 observed after removal of thyroids with high iodine content. There is 

 evidently some essential principle in the thyroid gland besides iodine 

 since no other preparation of iodine, other than the gland itself, has 



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