Anatomical Changes. Symptoms. 287 



intestines. The intestines may also show hemorrhages and 

 ulcerations, and in about two-thirds of the cases a well marked, 

 acute edema of the lungs with serous infiltration of the inter- 

 lobular connective tissue; sometimes gelatinous pseudo-mem- 

 branes will be found on the pleura, and hemorrhages under the 

 peri- and endocardium, as well as in the heart muscle. The 

 spleen is normal or only slightly enlarged, the liver hyperemic, 

 the kidneys show hyperemia, or an acute inflammation with 

 small hemorrhages. 



Symptoms. Horse-sickness usually develops after a period 

 of incubation averaging 6 to 7 days in two forms (Theiler). 



In the acute cases (Dunkop-Paardenziekte, Dun-Perre- 

 ziekte, pulmonal form) the body temperature rises within a few 

 days up to 40-42°. The patients show corresponding signs of 

 feeling ill, although the appetite remains unimpaired for a long 

 time. At the height of the disease, towards the end of the first 

 week, the animals are strikingly feeble, the pulse is frequent 

 and small, the heart throbbing, the respiration accelerated and 

 labored. In a small number of cases improvement and subse- 

 quent recovery take place in the course of the second week, the 

 fever diminishing. In most cases however at this time, 1 to 2 

 days before death, manifestations of edema of the lungs de- 

 velop, as a result of which the animals show very labored 

 respiration, at the same time passing great quantities of a 

 yellowish-white foam from mouth and nose, which is also ex- 

 pelled by spasmodic coughing. Swelling of the superficial lymph 

 glands may also be observed, and frequent manifestations of 

 metritis (Friedrichsen). In rare cases the course takes a 

 sudden unfavorable turn, after slight prodromal febrile mani- 

 festations lasting 4 to 6 days. The condition of the animal 

 becoming worse from hour to hour, the temperature drops and 

 death ensues inside of from 4 to 6 hours with symptoms of 

 dyspnea and heart weakness (Theiler 's peracute septicemic 

 form). 



In the subacute form (Dikkop-Paardenziekte, Dikkopziekte) 

 the disease develops in a similar manner, although considerably 

 more slowly. At the height of the fever, or possibly somewhat 

 later, the parts surrounding the orbits become edematously 

 swollen, and at the same time an exophthalmia develops ; then in 

 some cases edematous swellings appear on the forehead, on the 

 head, on the chest and abdomen, on the back and on the extremi- 

 ties, and sometimes even the tongue is swollen to a great extent 

 (blue tongue). In the meantime marked muscular weakness is 

 noticeable in the animals, in the majority of cases however 

 recovery finally takes place. 



Frel demonstrated by extensive physical-chemical blood and serum 

 examinations the following differences from normal blood: the volume 

 of red blood corpuscles and the viscosity is increased at the height 

 of the disease, later diminished; specific gravity, inside friction, and 



