THE ABDOMINAL FORM OF INFLUENZA IN THE HORSE. 215 



pulmonary, cardiac, or encephalic complications. Since it has per- 

 manently taken up its residence here it seems in a general sense to have 

 lost some of its gravity. During 1890 and i8gi it is said to have 

 produced many deaths in Paris and the neighbourhood, but the 

 evidence is not entirely satisfactory as to whether the cause of these 

 losses was influenza pure and simple. In great commercial and 

 industrial centres, where circumstances favour the development and 

 propagation of contagious equine diseases, several infections may 

 simultaneously be active in one stable. Thus influenza sometimes 

 co-exists with strangles, contagious pneumonia, or the pneumo-enteritis 

 caused by bad forage. I have observed cases of the kind. You will there- 

 fore see how difficult it sometimes is to solve these questions, and how 

 much more complicated the problems offered by practice really are 

 than you might imagine by perusing text-books on pathology. 



At the post-inorteui examination of animals dead of influenza most 

 of the organs exhibit extensive changes : congestion, ecchymoses, 

 infiltrations, and degenerative changes only revealed by the microscope 

 occur in varied combination, but the principal lesions are confined to 

 the mucous membranes of the digestive and respirator}' apparatus. 

 The intestinal mucous membrane is hyperaemic, swollen, ecchymosed, 

 and in places deprived of its epithelium. When incised it appears 

 infiltrated with liquid which escapes from the cut surfaces, and 

 coagulates in thin layers of gelatinous character. The submucous 

 connective tissue is often engorged with greyish or amber-coloured 

 liquid. The mucous membrane of the pyloric end of the stomach and 

 sometimes of the phar3Tix shows similar changes. 



Swelling of Peyer's patches is b}- no means constant, and I have 

 never observed necrosis or ulceration, lesions characteristic of typhoid 

 fever in man ; moreover Eberth's bacillus, the causal microbe of typhoid, 

 is never found either in these patches or at any other point in the 

 intestine. The respiratory mucous membrane is affected to a varying 

 degree. Often there is onl}- reddening and slight swelling of the larynx 

 and bronchi ; in some cases pulmonary lesions, such as catarrhal or 

 fibrinous pneumonia, or oedema of the lung, with or without pleural 

 exudate, predominate. Disease of the in}'ocardium and endocardium 

 is rarer than in pneumonia. Even when nervous symptoms occur, 

 change in the brain, spinal cord, or meninges is seldom marked ; very 

 often there is only trifling injection of the meninges and slight infiltra- 

 tion of the plexuses, the true nerve substance either of the brain or 

 medulla being rarely ecchymosed or softened. When the disease is com- 

 plicated with laminitis the podophyllous tissue is more or less congested. 



