ARSENICAL POISONING FROM SMELTER SMOKE IN 
THE DEER LODGE VALLEY, MONTANA. 
By D. E. Salmon, D.V.M., Montevideo, Uruguay, S. A. 
VI. 
The Nasal Ulcers of the Horses. 
The horses of the Deer Lodge Valley suffered from a peculiar 
form of nasal ulceration, locally called “ sore noses.” In the fall 
and early winter, one-half to two-thirds of the horses on some 
of the ranches might be found affected, and, in extreme cases, 
ioo per cent, presented such lesions more or less developed. 
The ulcers were usually situated in the floor of the nostril near 
to the septum, at or near the external orifice, and might be one 
and one-half or even two inches in diameter. Their surface was, 
in most cases, covered with thick, hard, dark-colored crusts, 
under which was more or less necrotic material, then the vascular 
floor of the ulcer, and beneath this a compact, fibrous layer, diffi¬ 
cult to cut. The ulceration was accompanied by considerable 
loss of tissue, so that when the healing occurred and the scar 
tissue contracted, the wing of the nostril was drawn towards the 
septum, partly, and sometimes almost completely, occluding the 
nostril. This sequel of the ulceration greatly damaged the ap¬ 
pearance of the horses, and, in some cases, decidedly interfered 
with respiration, especially when at work. In rare cases there 
was ulceration of the septum, with complete perforation. 
The farmers contended that this ulceration was due to the 
local action of the arsenic, which entered the nostril with the dust 
from the grass on which the animals were feeding, and, being 
dissolved by the secretion of the nostrils, exerted its destructive 
influence on the tissues over which this secretion flowed. The 
smelter company, on the contrary, held that it was not the result 
of arsenical action, and their experts broached the theory that it 
was due to microbic infection, stating as the basis for this con- 
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