100 DISEASES OF SWINE 



able time, very frequently pull through the disease all right and 

 recover. The same holds true with old boars. They are often 

 not attacked at all by the disease, and, when so attacked, they 

 also show a marked resistance to the disease and frequently recover. 



It is a most constant observation that young shoats, young 

 barrows, and young gilts are most early to show the sjTuptoms of 

 the disease, and also in this class of hogs the disease is most severe 

 and produces the most severe losses. Young pigs when attacked 

 by cholera almost invariably all die, or what few are left are so 

 stunted as to be worthless, and are usually profitably knocked in 

 the head. 



As a general statement, then, it may be put down that hog- 

 cholera may appear at any age, but that it is more likely to break 

 out in a herd of young animals, and that the younger the animal, 

 the more severe the outbreak, as a rule, and the higher the death- 

 rate among the affected hogs. Old sows and old boars seem to 

 possess a more or less strong resistance, both to the attack and to 

 the severity of the symptoms, even when the disease does attack 

 them. It must be remembered, however, that even old sows and 

 old boars are often carried away by the disease. This is especially 

 true in certain outbreaks of hog-cholera which appear to be espe- 

 cially severe and especially fatal, often sweeping the pens clear of 

 every living hog in the course of a few days. This kind of an 

 outbreak is especially likely to occur in newly settled districts and 

 in locahties where outbreaks of cholera have been absent for a 

 number of seasons. In these cases it seems that when the disease 

 is introduced or recurs that it is especially severe, and the herds 

 melt away like snow on a hot summer day, and it is not unusual 

 to find large numbers of animals dead in the course of forty-eight 

 hours from the beginning of an outbreak on any given farm. 



(2) Sex. — This also is to some extent a determining factor in 

 the susceptibility of an animal to cholera. In the young barrows, 

 young boars, and gilts sex seems to make little or no difference in 

 the appearance of the disease. An acute epidemic of cholera ap- 

 pears to attack animals of male or female sex with equal frequency 

 and equal severity. In the adult animals, however, the uncas- 

 trated male appears to be less susceptible to attack and more 

 resistant to the disease if attacked. That is to say, they are less 



