Diseases of the Mediastinum. 393 



often with caseated or calcified centres, or the whole gland or 

 group of glands may be similarly invaded and necrotic, making 

 a diseased mass of 12 inches in its longest diameter. There may 

 or may not be infiltration into the surrounding connective tissue. 

 In such cases the pressure upon vital thoracic organs may 

 be such as to produce the train of symptoms mentioned above 

 under mediastinitis. In cattle, constant tympany of the rumen 

 is a prominent feature, becoming aggravated after meals. The 

 normal, healthy, eructations of gas may be suspended, dyspnoea 

 appears under slight exertion and distension of the jugular, 

 cervical and facial veins are often marked symptoms. When the 

 tubercular glands have attained to a great size the dull, flat 

 sound on forcible percussion may show their outline. In any 

 case a cough is easily roused by exertion, and if the lungs are not 

 seriously implicated this is likely to be especially dry or husky. 

 Other signs of tuberculosis may be shown : in the lungs cir- 

 cumscribed areas of flatness on light percussion and of wheezing 

 or other abnormal sounds, with, in some instances emphysema- 

 tous, drumlike tympanitic percussion sound ; in the throat, 

 wheezing guttural breathing and distinct swelling ; in the ab- 

 domen capricious appetite, impaired rumination, a tendency to 

 scour on forced feeding and enlarged mesenteric glands felt 

 through the rectum ; in the superficial lymph glands asymmet- 

 rical enlargements, etc. In all cases of suspicion the tuberculin 

 test should be applied. 



While some cases survive slight tubercular infection and even 

 recover, there is no such hope in connection with extensive de- 

 posits, and, as in fatal, chronic, infectious diseases generally, 

 treatment only becomes a means of perpetuating and extending 

 the infection, thus giving permanence and prevalence to a disease 

 which should be completely stamped out. If preserved at all, 

 for breeding purposes, it should only be in the most rigidly 

 secluded herds from which all opportunity for extension is 

 carefully guarded. (See Tuberculosis, Vol. IV). 



