340 PRINCIPLES OP VETERINARY SCIENCE 



This compound is essential to the development of an animal. 

 When there is need of this compound and the iodin content of 

 the food is not sufficient to supply it, the gland enlarges to let 

 more blood pass through in a given time. The cause of many- 

 cases of goiter, therefore, appears to be either a failure of the 

 intestines to absorb the iodin from the feed, or a failure of the 

 thyroid gland to absorb and store the iodin that is in the blood. 



Symptoms. — Calves, foals, and lambs affected with goiter 

 are either born with an enlarged neck or develop one soon there- 

 after. They are weak, lifeless, and fail to thrive. Often the 

 enlargement presses on the windpipe to such an extent that 

 breathing is interfered with. Hairless pigs are of normal weight 

 and size. They may be born alive but always die sooner or later 

 if no hair is present. When entirely hairless the skin is smooth 

 and shiny, except for a few hairs around the eyes and snout. 

 The hoofs are thin and brittle. All pigs in the same litter are 

 not always similarly affected; some may be hairless, others 

 scantily-haired, and still others normal. The sow giving birth 

 to pigs of this kind has also been found to have an enlarged 

 thyroid, but does not show the characteristic large neck on account 

 of her neck being so fat and fleshy. Goiter in the sow neither 

 seriously affects her health, nor renders her flesh unfit for food; 

 but unless corrected does interfere with her breeding propensity. 



The thyroid gland of a normal new-born pig is about the size 

 of a pea and contains no iodin, while that of a hairless pig is the 

 size of a hickory nut and when dry contains about 0.2 per cent, 

 iodin. The gland in a normal sow varies in size, but usually is 

 not larger than a walnut, while in a sow that has given birth to 

 hairless pigs it may be as large as a man's fist. 



Treatment. — Most feeding stuffs contain enough iodin to 

 meet the needs of animals. Only When an animal is incapable 

 of absorbing sufficient iodin for body needs is treatment neces- 

 sary. At the Wisconsin Agricultural Experiment Station goiter 

 resulting in hairless pigs has been corrected by giving the sow 

 potassium iodid in her feed during the last sixty days of the gesta- 

 tion period. Ten grams of finely pulverized potassium iodid 

 crystals are mixed with each 100 pounds of feed. When hogs 

 are on pasture and get plenty of exercise the disease occurs so 

 rarely that the remedy mentioned above need not be given. The 

 liberal feeding of roughage and concentrates not high in protein 



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