OF VETERINARY MEDICINE. 181 



tana, North and South Dakota, Illinois, Iowa, Manitoba and 

 several countries in Europe. 



It has been under investigation for the last three years by 

 Drs. John R. :\Iohler, M. Francis, R. P. :\Iarsteller, Winfred B. 

 Mack, A. T. Kinsley, L. \^an Es, and others. 



It is a distinctly infectious disease affecting horses, mules and 

 asses. It used to be supposed to be confined to swampy regions, 

 but within the last three years has been found in altitudes as 

 great as 7,500 feet. 



Etiology. — The specific virus has not yet been isolated, but it 

 is known to be specific by inoculation with the blood and blood 

 serum producing the disease, even after the serum has been fil- 

 tered through a fine Pasteur "filter, consequently the virus must 

 be infinitesimally small, or a toxine. 



Dr. Van Es has recently, 1911, found that the urine and feces 

 contain the virus, and that horses eating the litter soiled by 

 horses with this disease develop it. The Pasteur filter would 

 remove all known bacteria and protozoa. 



Semeiology. — It is characterized by progressive anemia and 

 remittent fever. The horses become dull, listless, weak and 

 finally stagger; the temperature may run as high as 106 for a 

 few days, then gradually fall to 102 and stay around that point 

 for two or three weeks, and then rise again for a week ; the pulse 

 becomes rapid, small, hard and thready, and jugular pulse is seen 

 after a few weeks. The mucus membranes gradually become 

 paler and paler; sometimes they develop a yellowish or even a 

 mahogany color in some cases. They also occasionally present 

 hemorrhage spots (petechiae). Oedematous enlargements on the 

 under side of the belly, sheath, mammae and legs. There are pro- 

 found changes in the blood. The red corpuscles from a normal 

 of seven million per cubic millimeter sometimes drop as low as 

 two millions. There is little or no change in the number of white 

 corpuscles. The blood becomes thin and watery. The appetite 

 usually remains good throughout the course of the disease. 



Post Mortem. — Great emaciation and loss of fat are seen, all 

 parts are extremely pale. Local hemorrhages may be seen, espe- 

 cially in and around the heart, which is generally enlarged. The 

 lungs are studded with petechiae, and there is besides a little 



