SURRA. 559 



The temperature on the clay of inoculation, and, in fact, for several 

 days afterwards, may remain nomial in character, there being only a 

 few degi-ees difference between the morning and evening observations. 

 In other cases there may be a slight rise from the first evening, and a 

 gradual progi-essive rise until the swelling at the seat of inoculation 

 shows signs of reduction in size, when the temperature generally 

 takes a decided rise again, and may attain 104° or 105.8° F. This 

 elevation will last a varying period of from two to six days, and on 

 the day following its onset the ordinary symptoms of fever will be 

 noticed, and in addition there will be petechiae on the conjunctival 

 membranes, lachrymation, a slight mucous discharge from the nose, 

 and in severe cases some edema of the lower portion of the legs, and 

 perhaps of the sheath in horses. At the termination of the period 

 of fever the temperature will be found to have fallen to normal or 

 nearly so; the animal will present a brighter aspect, and there is 

 every appearance of its return to health ; but in a few days the animal 

 again appears dull and half asleep ; the temperature becomes elevated 

 and a relapse takes place, and a repetition of all the symptoms in the 

 primary paroxysm, including the reappearance of the parasite, is 

 observed. 



Diagnosis. — Certain sjanptoms (anemia, fever, petechise, ravenous 

 appetite, extreme emaciation, high mortality, etc.) would naturally 

 give rise to a suspicion of surra. The positive diagnosis should, 

 however, be made with a microscope. In case of suspected surra no 

 delay in confirming or disproving the suspicion should be permitted. 



Treatment. — No satisfactory treatment is known. Intravenous in- 

 jections of Fowler's solution of arsenic give temporary relief, but re- 

 lapses occur. In view of the great economic importance of this 

 disease, it would not be advisable to attempt to treat any sporadic 

 cases should they occur in this country. On the contrary, the animals 

 should be slaughtered immediately and their carcasses promptly 

 burned. 



OSTEOPOROSIS OR BIGHEAD. 



By John R. Mohler, V. M. D., 

 Chief of the Pathological Division, Bureau of Animal Industry. 



Osteoporosis is a general disease of the bones which develops slowly 

 and progressively and is characterized by the absorption of the cal- 

 careous or compact bony substance and the formation of enlarged, 

 softened,, and porous bone. It is particularly manifest in the bones 

 of the head, causing enlargement and bulging of the face and jaws, 

 thereby giving rise to the terms " bighead " and " swelled head," which 

 are applied to it. The disease affects horses, mules, and asses of all 

 ages, classes, and breeds, and of both sexes, and is found under all soil. 



