176 DISEASES OF THE BLOOD 



of the epicardium and endocardium, spleen and bowels; 

 swelling of the lymph glands which are usually blood-shot; 

 changes in the color and structure of the bone-marrow, 

 especially of the long bones. A longitudinal section of the 

 femur or humerus, for instance, will show in the bone-marrow 

 dark red areas which are sharply demarcated from the 

 yellow portion. In acute cases there may be marked swelling 

 of the spleen, a symptom not so manifest in chronic cases. 

 The blood may show no macroscopic changes; in chronic 

 cases it appears of lighter color, watery. While the condition 

 of the cadaver may be good in acute cases, in chronic ones 

 it is usually emaciated and shows edematous swellings of the 

 skin of pendant portions (sheath). Icteric discoloration of 

 the tissues is not rare. 



Symptoms. — The period of incubation after artificial inocu- 

 lation varies from five to nine days. From natural infection 

 it is usually two or three weeks. Two clinical types of the 

 disease may be recognized : (a) The acute form which begins 

 suddenly with symptoms of languor and muscular weakness. 

 The horse tires easily at work, may fall to the ground in 

 harness and must be assisted to its feet. Quite often this 

 weakness is most pronounced in the hind parts ("loin 

 distemper"). 



Fever is a constant symptom, the temperature reaching 

 its acme in two or three days, ranging from 104° to 107° F. The 

 fever is of a remittent or intermittent type continuing until 

 the death of the patient, periods of increased temperature 

 alternating with feverless periods lasting one or two days. 

 The pulse usually ranges from 60 to 90, is soft and weak. The 

 heart beat is often tumultuous, a symptom increased by 

 exercise. 



The conjunctiva appears puffy, swollen, slightly tinged with 

 yellow and occasionally spotted with petechia? which are 

 principally on the nictating membrane. There is usually 

 slight lacrimation. The nasal mucosa is congested and shows 

 petechia;. There may be a slight nasal discharge of reddish 

 color. The patient often shows diarrhea, the feces blood- 

 stained, and a constant symptom is albuminuria, the amount 

 of albumin varying from a mere trace to 1.5 per cent. The 



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