642 DISEASES OF SWINE 



Corn is an excellent food for hogs when properly fed, but it does 

 not form a well-balanced diet when fed without any other grain. 



When for some reason the mother of the litter dies or fails to 

 nurse the pigs, and it is necessary to bring them up on cows' milk 

 or some other form of food, rickets may develop. The milk of the 

 cow, while suitable for the growth of calves, is not of the proper 

 quality for feeding rapidly growing young pigs. As a result, the 

 bone development in pigs fed in this manner is delayed and typical 

 rachitis may occur. 



Disease of the stomach and intestines of a chronic type is 

 another frequent cause of rachitis. As a result of the inflam- 

 mation of the bowels and stomach, food is not properly digested and 

 absorbed, and while the animal may be taking into the body the 

 necessary amount of food and of the proper quality, it does not get 

 the usual benefit from it, on account of being unable to properly 

 digest and use it in building of bone and other tissues in the body. 



In like manner, presence of worms in the stomach and intestines 

 may sufficiently interfere with digestion and assimilation of foods 

 to result in lack of development and growth. These parasites are 

 perhaps a more frequent cause of digestive disturbances than is 

 generally recognized. 



Changes Produced. — As a result of the lack of calcium or bone- 

 forming salts the bones fail to harden as they should. The constant 

 movements and the weight of the animal produce irritation of the 

 soft bone-forming tissues, and, as a result, a sort of inflammation 

 is produced. This results in an increased production of cartilages, 

 especially around the ends of the long bones. When this process 

 has been continued for some time it will be found that the ends 

 of the bones are enlarged and the long bones may show considerable 

 deformity from bending under the weight of the body. The swell- 

 ing of the ends of the bones gives a swollen appearance to the joints, 

 and this is one of the first symptoms noticed by the owner. As a 

 result of the weakness of the bones it is not unusual for them to 

 break under the weight of the animal. This is especially likely to 

 occur in the case of the long bones of the hind limbs, producing 

 symptoms quite similar to those described under Paralysis of the 

 Posterior Part of the Body. 



Symptoms. — If the animals are closely observed it will be found 



