POLL-EVIL. 407 



four to six weeks. But more frequently infection, produced 

 through skin abrasions caused when the bursa was injured, extends. 

 Chronic inflammation sets in, the bursal walls and surroundings 

 become thickened ; small spherical growths, proceeding from the 

 inner surface of the bursa, separate after a time, so that the cavity 

 may become filled with a great number of rice-like grains. There 

 are frequently large masses of these corpora oryzoidea. Vincent 

 erroneously considered them to be entozoa. When chronic inflam- 

 mation has occurred, recovery is slow ; but the working usefulness 

 of the horse may not greatly suffer. The swelling in such cases 

 becomes smaller, harder, and less movable with the lapse of time. 

 In most cases, however, pyogenic infection of the bursa follows, 

 the inflammatory appearances increase greatly, spread to the neigh- 

 bouring connective tissue and muscles (parabursitis), and finally, 

 after acute pain and fever, end in abscess formation with perfora- 

 tion of the skin. The finger, introduced into the abscess cavity, 

 detects necrosis of the ligamentum nuchas or other tissue and 

 purulent inflammation of the bursa, which may continue for months 

 and baffle treatment. Sometimes inflammatory symptoms, and 

 especially pus formation, abate, although purulent fluid, mixed 

 with blood, continues to flow from the small fistulous opening. 

 Necrosis may extend to the occipito-atloid ligament, the occipital 

 bone, first and second cervical vertebrae, and the deeper lying 

 portions of the ligamentum nuchse and cause inflammatory inter- 

 muscular swelling in the throat. Recovery is most tedious, especially 

 if proper treatment is not adopted, and unless in valuable subjects, 

 slaughter may be advisable. The thickening left produces no 

 difficulty in moving the neck ; but permanent stiffness occasionally 

 results from adhesion between two vertebrae (Lafosse) ; and fatal 

 cases occur from embolism, from spreading infection, or finally, 

 from pus breaking into the vertebral canal. Death then occurs 

 suddenly, with general paralysis and epileptiform seizures. 



The course depends principally on whether the tissues remain 

 aseptic. Should this be the case recovery follows in four to six 

 weeks ; otherwise the above described complications are very apt 

 to occur and the disease to become chronic. The prognosis is then 

 unfavourable. Special care must be exercised in giving an opinion 

 where there is much suppuration, swelling and pain. Except in 

 valuable animals treatment is seldom justified when suppuration 

 has extended to deep-seated structures and the lower portions of 

 the ligamentum nuchae have become necrotic. 



Treatment. In recent aseptic conditions of the bursa, inflam- 



