INFECTIOUS LEUKEMIA OF CHICKENS 325 



more or less extensive hemorrhages occur in the various 

 organs. 



Course.— The disease is usually chronic. The acute form 

 is very rare in small animals. The course usually extends 

 over a long period, and complications are common. 



Diagnosis.— The characteristic involvement of the lymph 

 glands, spleen and liver, and the increase in the number of 

 white corpuscles, will make the diagnosis comparatively 

 easy. A microscopic examination of the blood is necessary 

 in order to make the diagnosis accurate. The differentiation 

 between the forms of leukemia is determined definitely in this 

 manner. 



Prognosis.— Very unfavorable. When the disease is once 

 established there is little hope of recovery. 



Treatment.— Owing to the pathological changes present 

 not much can be expected in the way of treatment. In some 

 cases the patient's general condition may be improved by 

 allowing plenty of nutritious food and administering altera- 

 tives and tonics. Iron and quinin citrate (0.2 to 0.4 twice 

 daily) have given the best results. Transfusion of blood 

 has proved unsatisfactory in small animals. 



INFECTIOUS LEUKEMIA OF CHICKENS. 



Definition.— An infectious disease of chickens probably 

 produced by an ultramicroscopic virus. It is characterized 

 by an increase in the number of leukocytes, an atrophy of 

 the marrow of the bones, and an increase in the size of the 

 spleen and liver. In many cases the number of red blood 

 corpuscles is reduced and the white ones increased. 



Occurrence. — Up to the present time the disease is found 

 only in chickens. Other fowls are not affected. It often 

 appears in an enzootic or epizootic form when large numbers 

 in a flock or community will be affected. 



Etiology.— From rather extensive investigations made 

 with this disease it is evidently due to a virus found in the 

 affected organs, viz.: The spleen, lymph glands, and bone- 

 marrow. The disease is easily transmitted by intraperi- 

 toneal or intravenous injections, while subcutaneous injec- 



