CLINICAL OBSERVATIONS ON ROARING. 
811 
CLINICAL OBSERVATIONS ON ROARING. 
By W. E. Williams, Professor of Surgery, New York State 
Veterinary College. 
In the Review for July, 1900 (Vol. XXIV, p. 240), Dr. 
Riautard presents a brief resume of discussions upon the ques¬ 
tion of the heredity of roaring by such eminent scientists as 
Nocard, Ravalard, Cagny, Barrier, and Rabat. The latter of 
these clings to the belief in a hereditary predisposition. Much 
confusion has been caused by including under the term tc roar¬ 
ing ” all cases of disease resulting in a loud roaring noise dur¬ 
ing exertion, a heterogeneous collection of maladies of the 
greatest possible variety and scarcely related in any way. 
For our purposes we shall restrict the term to the predomi¬ 
nant pathologic condition causing this symptom, consisting of 
paralysis and atrophy of the muscles supplied by the left re¬ 
current laryngeal nerve, and which upon investigation show no 
sufficient cause for the paralysis, such as the pressure of a tumor 
on the nerve or the separation of the nerve, owing to a trauma¬ 
tism. 
In the article above quoted the query is put, “ Why should 
‘Ormonde,’ himself a roarer, produce roarers when in England 
and when taken to America not have one roarer to his credit ? n 
Other cases of confirmed roarers used as breeders without pro¬ 
ducing roarers are cited. The query concerning “ Ormonde ” 
is significant. Why did his British progeny “ inherit ” his 
defect and his American produce remain free ? If we admit 
“ heredity ” as the ruling factor we should have to conclude 
that there was a hereditary predisposition in the American 
mares against roaring which was greater than “ Ormonde’s ” 
pro-roaring tendencies. But the American mares were probably 
from British stock in which roaring has been common through¬ 
out history, and the question arises then whether the mares in 
South America had acquired an immunity against the malady. 
This at once raises the question of climatic influence on 
roaring, and unfortunately we have no statistics at hand to af¬ 
firm or deny such suggestion. In the writer’s observations, how- 
