510 DISEASES OF THE HORSE. 
VACCINATION. 
In recent years vaccination for the prevention of certain infectious 
diseases has been successfully developed, and without a doubt the 
future has a great deal in store for this phase of prevention. At the 
present time vaccination has been found effective against blackleg, 
hog cholera, anthrax, lockjaw, strangles, rabies, hemorrhagic sep- 
ticemia, white scours, etc. It is always essential, of course, that the 
products used for the vaccination be pure and potent; also they 
should be employed only with the advice of competent authorities 
and with proper care. The biological products prepared for the 
cure and prevention of infections are prepared by manufacturers 
who, in order to conduct an interstate business, are required to 
obtain a license from the United States Department of Agriculture 
for the manufacture of such preparations. 
Since July 1, 1918, the Department of Agriculture, by an act of 
Congress of March 4, 1918, has had control of the manufacture of 
biological products for the treatment of domestic animals. The 
numerous complaints which were received from time to time rela- 
tive to the impotency of some of the preparations, and also the fact 
that in some instances the use of the products were directly respon- 
sible in causing outbreaks of disease, made the necessity for such 
control obvious. This supervision is no doubt of far-reaching im- 
portance, as it assures the users that the preparations are reliable. 
INFLUENZA. 
Synonyms.—Pinkeye, typhoid fever, epizooty, epihippic fever, hepatic fever, 
bilious fever, etc.; fiévre typhoide, grippe (French) ; Pferdestaupe (German) ; 
gastro-enteritis of Vatel and d’Arboval; febris erysipelatodes, Zundel; typhus 
of Delafond. 
Definition —The term influenza is applied to a febrile, contagious, 
infectious disease of horses, which is characterized by a blood infec- 
tion, with inflammation of the mucous membranes, which frequently 
involves the lungs. Inflammatory complications also occur in the 
form of swellings of the subcutis, tendons, and tendinous sheaths 
and laminz of the feet. The causative agent has not been satis- 
factorily established. One attack usually protects the animal from 
future ones of the same disease, but not always. An apparently com- 
plete recovery is sometimes followed by serious sequele of the ner- 
vous and blood-vessel systems. Under certain conditions of the at- 
mosphere or from unknown causes, the disease is very liable to as- 
sume an epizootic form, with tendency to complications of especial 
organs, as, at one period, the lungs, at another the intestines, etc. 
The first description of influenza is given by Laurentius Rusius 
in 1301, when it spread over a considerable portion of Italy, causing 
