INFECTIOUS ANEMIA OF THE HORSE 175 



industry and should it become more wide-spread the financial 

 loss resulting would be very great. 



The disease will remain on a given farm for a number of 

 years (10-15) where annually it causes losses among the 

 ' horses. 



Etiology. — Infectious anemia is due to a filterable virus 

 which cannot be demonstrated by staining methods nor by 

 cultivation. The virus is contained in the blood, urine, and 

 feces of both clinical cases of the disease and apparently 

 healthy horses. According to some authorities the feces, 

 however, will not transmit the disease. It is very probable 

 that the feces are infectious only when mixed with infected 

 urine. 



The disease may be transmitted by virulent blood or urine 

 given intravenously, subcutaneously or orally. Other domes- 

 ticated animals and guinea-pigs do not seem susceptible. 1 



Natural Infection. — The disease seems to be taken up through 

 the digestive tract in food, water, stable litter, etc., which 

 have become contaminated with the urine and feces of in- 

 fected animals. On poorly drained pasture fields pools of 

 water may easily become polluted with the discharges of 

 infected horses, especially with urine, thus serving as sources 

 of infection. The disease does not seem to be contagious or 

 directly communicable. Cases are recorded where healthy 

 horses have been confined in stables and mingled freely for 

 months with sick ones^without evidence of any transmission 

 of the disease. It is possible that patients are not eliminating 

 the virus continuously and during all stages of the disease. 



Suckling colts are not infected through nursing diseased 

 mothers nor has an intra-uterine infection been observed. 



The disease is usually introduced into a community by 

 the purchase of either a clinical case or an apparently healthy 

 horse ("missed case"). 



Necropsy. — In general the postmortem findings are those 

 of an acute or chronic septicemia. Depending upon the dura- 

 tion of the disease they offer great variations. There are no 

 postmortem changes which can be considered pathogno- 

 monic. The principal changes noted are: Petechia? and 

 ecchymoses occurring under the serous membranes especially 



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