(398 Enzootic S])iiial i'aralysis of the Horse. 



Aceoiiliii;^ to DaliJstiuiii a contagious lumbar paralysis has lieeu kuowu in Den- 

 mark and ISweden for more than 50 years, which is probably the same disease. 



Christianssen and Kasmussen observed weakness of the hind quarters in foals 

 from 1 to 2 years old which lasted for months and even 1 to 2 years. 



In Austria a similar disease has been observed among the army horses in 

 the neighborhood of N'ienna. This was considered by Szerdahelyi to be due to 

 alkaloid poisoning. 



Small outbreaks have been recorded in Italy by Perucci in Bologna. 



Etiology. A streptococcus which is noncapsulated has 

 been described as the cause of the disease by Schlegel, Zwick 

 and Perucci; and Schlegel has named it streptococcus nielano- 

 genes. The organism can be found in the blood, parench^ina- 

 tous organs, bone marrow, spinal cord, the gelatinous infiltra- 

 tion around the bladder and genital organs and in the urine. 

 In the circulating blood it occurs either as mono- or diplo- 

 cocci, or in short chains, but as a general rule the chains are 

 longer. These long chains are prominent in the acute cases. 



Staining. The streptococcus stains easily and well with the l)asic 

 anilin dyes, and according to Zwick and Perucci, is Grram-positive ; but 

 according to Schlegel, it is Gram-negative. 



Cultivation. The organism is an aerobe and the optimum temper- 

 ature for growth is that of the liody. The best growths are obtained 

 on media containing detil)rinated rai)bit or horse blood. In broth col- 

 onies develop in large numbers in 24 hours. These settle to the l)ottom 

 or on to the sides of the vessel, the liquid remaining clear. Perucci 

 observed a rapid decrease in the profnseness of growth in simple broth cul- 

 tures and also on other media containing no ])lood. In broth contain- 

 ing ])lood, growth is abundant, and the colonies which fall to the bot- 

 tom appear brownish-gray in color, owing to decomposition of the blood- 

 pigment. In agar growth takes place along the needle track in the 

 form of a fine grayish-white thread with down-like outgrowths. On 

 l)lood-agar the organism produces pale grayish-white colonies surround- 

 ed ])y a deep browm zone, resulting from the decomposition of the blood 

 by the streptococci. Nieter found the last-mentioned characteristic, 

 common to many other streptococci. 



Pathogenicity. The organism isolated hy Schlegel causes a gen- 

 ci-al infection in the small experimental animals, characterized by pa- 

 ralysis of the hind quarters, and other lesions similar to those seen in a 

 natural case in the horse. Perucci, however, was able to infect rabbits 

 only by intravenous, intraperitoneal, and subcutaneous inoculation with 

 blood or culture, the inoculation setting up a general disease, associated 

 ■\vith degeneration of the parenchymatous organs. In the horse, Schle- 

 gel observed only a temporary weakness of the hind cpiarters after the 

 intravenous introduction of large (juantities of culture. Zwick produced 

 the typical disease by repeated injections, and Perucci succeeded with 

 a single intravenous inoculation of 10 cc. of broth culture. The admin- 

 istration of cultures by the mouth caused only a transitory paresis in 

 a horse (Zwick), while intraperitoneal inoculation caused a slowly pro- 

 gressive lumbar weakness without hemoglobinuria, a sero-purulent peri- 

 tonitis, and lesions similar to those seen in a natural case (Schlegel). 



So far the natural infection is not know^n. Schlegel sup- 

 poses that the streptococci maintain a saprophytic existence in 

 the intestine of otherwise healthv horses, and under certain 



