442 INFLUENZA IN HORSES 
INFLUENZA IN HORSES 
Synonyms: Epizootic catarrhal fever; epizodtic catarrh; horse 
distemper; pink eye; mountain fever; shipping fever; typhoid 
fever; stable pneumonia. 
Characterization. Influenza is an acute infectious disease charac- 
terized by a rise of temperature and a catarrhal condition of one or 
more of the mucous membranes, more especially of the head, or by 
inflammation of the lungs and pleuree. One or more of the internal 
organs may become affected. It is a disease of horses, although asses 
and mules are susceptible and a few cases are reported of its being 
transmitted to man and to dogs. It appears sometimes in sporadic 
form and often in epizodtics. 
Influenza is a generic term employed to designate a large variety of 
symptoms. Dieckerhoff designated the pulmonary form contagious 
pleuro-pneumonia. A somewhat careful analysis of the manifesta- 
tions suggests that possibly influenza includes a number of etiologi- 
cally distinct diseases, 7. e., morbid conditions brought about by 
different causative factors. The term has long been employed to 
designate a considerable variety of equine epizodtics, the independence 
of which could not be fully established. The disease, as it is seen in 
the horse, suggests further that possibly it is in its beginning a general 
affection because of the early rise of temperature and that later in its . 
course it becomes, to a limited extent, localized. At present influenza 
is restricted to groups of symptoms and lesions in the horse that are 
analogous to those of lagrippeinman. As it is not usually fatal, little 
progress seems to be made in acquiring knowledge concerning the 
nature of its morbid anatomy. There is much need for further inves- 
tigation of this very common malady. 
History. According to the writings of Falke, influenza was recog- 
nized in very early times. There is evidence that it was known in the 
fourth and fifth centuries. It was described by Low in 1729 in an 
equine epizoétic which had spread over Southern Europe. It is also 
stated that cases of its having been transmitted to man had occurred. 
Gibson observed it in 1872 in London and in different districts of 
England. It raged in epizodtics in 1760, 1776 and 1803. The 
disease was widely disseminated during the last century. The more 
important epizodtics are reported in the years from 1813 to 1815, 1825 
to 1827, 1836 to 1840, 1846, 1851, 1853, 1862, 1870, 1873, 1881 to 1883, 
and 1890. Anker, who described influenza in Switzerland in 1826, 
