LUNG PLAGUE OF CATTLE 411 



Symptoms. — ^The period of incubation is from one to four 

 weeks. In many instances it appears shorter, the early symp- 

 toms (temperature) being obscure and passing unobserved. 

 In very hot weather the attack is often more sudden and 

 severe than in the cold season. 



The symptoms are very varied. From a clinical standpoint 

 usually two stages can be recognized. During the first stage 

 (so-called occult stage) a peculiar, short, weak, painful cough 

 is heard, especially after drinking or eating, or when driven up 

 or out of the barn. The patients are languid, show capricious 

 appetite, suppressed rumination and stand with back arched, 

 head down and ears pendent. Driving the animal induces 

 dyspnea. The temperature is usually somewhat elevated 

 (one or two degrees). This condition may exist from two to 

 four weeks, and lead to recovery or the symptoms may 

 become more pronounced. Second stage : The temperature 

 ascends to 104° to 108° F., and severe dyspnea develops, the 

 mouth is held open, tongue protrudes, and each expiration is 

 accompanied by a loud moan. The patient usually stands 

 with its neck extended and elbows turned out; if it lies down 

 it does so on the affected side. There is usually complete 

 loss of appetite, suppressed rumination and cessation of milk 

 flow. There is often a mucopiu-ulent nasal discharge stained 

 with blood. The feces are dark and dry; later a profuse, fetid 

 diarrhea develops. On percussion (which is painful) over the 

 affected side an extensive area of dulness may be detected. 

 On auscultation bronchial tones and rales and occasionally 

 frictional soimds are heard. If the consolidated area is not 

 near the lung surface, however, percussion and auscultation 

 are negative. The abnormal respirations are best heard after 

 exercising the patient. 



In fatal cases the patient rapidly emaciates, becomes hide- 

 bound, anemic, cachectic and dies of exhaustion in three to 

 six weeks. 



If recovery occur, it generally takes place gradually and is 

 not always complete, the patient remaining unthrifty for a 

 long time. 



Diagnosis. — Intra mtam a positive diagnosis is very diffi- 

 cult or impossible. Usually only a careful necropsy will 



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