178 InHueiiza of Horses. 



bacillus probably has an active part. Bourget & Prevost finally found 

 a virulent form of proteus in the pleural exudate of several horses. 



Anatomical Changes. In the catarrhal form of influenza 



an acute hyperaeniia. of the mucous nieiiibranes develops in 

 the digestive tract or in the air passages, or possibly in all 

 the mucous membranes. This condition is associated with an 

 edematous infiltration of the submucous connective tissue, as 

 a result of which the mucous membrane, especially in the larynx 

 and in the pyloric portion of the stomach, and in the small 

 intestines, forms thick gelatinous folds. In the small intestine 

 the solitary follicles, and the Peyer's patches are swollen, and 

 moreover the reddened mucous membrane contains in places 

 superficial erosions or even deep ulcers (Rips). The mesen- 

 teric lymph glands are greatly swollen, their tissue is reddish- 

 gray and moist. 



Very frequently the subcutanous connective tissue is in- 

 filtrated with a clear, or somewhat cloudy, readily coagulating 

 serous fluid. These infiltrations may occur at different parts 

 of the body, especially in the parts surrounding some of the 

 tendons of the extremities. A similar fluid may be contained 

 in the tendinous sheaths in considerable quantities. The yellow, 

 gelatinous tissue is in such cases studded with small hemor- 

 rhages, and similar changes are sometimes present in the sub- 

 and retroperitoneal connective tissue, especially in the imme- 

 diate vicinity of the kidneys. The body cavities may also 

 contain various quantities of a pure or slightly cloudy, reddish 

 exudate. 



The other internal organs are not much changed. A mod- 

 erate, acute swelling of the spleen may be present, also 

 hyperaemia or acute edema of the lungs, cloudy swelling of 

 the heart muscles, of the liver, and of the kidneys. Hyperemia 

 of the meninges, and even a slight acute hydrocephalus internus 

 may be found. 



In the pectoral form of influenza, necrotic pneumonia, in 

 association with sero-fibrinous pleurisy, represents the most 

 important and common anatomical change. The pneumonia 

 sometimes occurs in the form of lobular broncho-pneumonia, 

 or the inflammatory process extends in the form of a lobular 

 pneumonia, affecting at the same time, large contiguous areas 

 of one or both lungs. In the first case the lung contains only 

 a few dense hepatized catarrhal or hemorrhagic areas; the 

 tissue in immediate surroundings of these areas is seronsly 

 infiltrated; while in the second case, the lower sections of the 

 lungs are uniformly hepatized throughout large areas. The 

 affected lung tissue breaks readily, the cut surface is granular, 

 and depending on the stage of formation, it is either grayish- 

 brown, grayish-red, or yellowish-gray. In the parts still con- 

 taining air, besides the hyperemia or acute edema, the con- 

 nective tissue walls are gelatinously infiltrated. 



