THE SWAMP FEVER OF HORSES. 
225 
to an abscess in the hoof. At the end of June the horse weighed 1,230 
pounds. It seemed healthy and was worked almost daily. A blood count 
gave: red cells, 8,500,000; white cells, 11,600; hemoglobin, 75 percent." 
A differential count was made of 500 white cells from two slides, with the 
following results : Polymorphonuclears, 71 .5 per cent; lymphocytes, 16.5 
per cent; large mononuclears, 6 per cent; eosinophiles, 3.75 per cent; 
transitionals, 2.25 per cent — equals 100 per cent. 
At the present date, October 31, 1910, the horse seems to be in perfect 
health. It weighs 1,380 pounds; its pulse rate is about 35, its tempera- 
ture is normal, and there is no sign of edema or petechial hemorrhages. 
It seems possible that an occasional rise, during the summer, of its tem- 
perature may be accounted for by a more than usually severe day's work. 
If it were not for the distinct rises in temperature which 
followed the inoculation of blood from this Grey Gelding, 
especially into Horse No. 2, and also into Horses Nos. 4 and 
5, it would be permissible to question whether it were ever 
infected with Swamp Fever. As it is, it seems as though 
this were a case from which the symptoms have disappeared 
temporarily or, it may be, permanently. 
The Black Gelding was an undoubted case of Swamp 
Fever; it died twelve months after symptoms were first 
noticed. 
X. Sub-inoculations. — It has been shown that Swamp 
Fever can be transmitted to horses, mules or donkeys by 
the inoculation of blood, or blood serum, from infected 
animals ; five cubic centimeters of blood is sufficient to 
transmit the disease. The blood of infected animals is infec- 
tive up to twenty-four hours after death. The period of 
incubation, between inoculation and the appearance of the 
first symptom — a rise in temperature — lasts for from ten 
days to one and one-half months. In horses the experi- 
mental disease runs a chronic course and lasts for from two 
months to one and a half years, or longer. 
Attempts to inoculate guinea-pigs, rabbits, cats, dogs, and 
cattle have failed. 
The results of our attempts to transmit the disease are 
recorded below. 
