320 Hairless Pig Malady. I 
be reestablished. This condition could apply to the fetus as well 
as to the mother. This hypothesis would not preclude the 
possibility of a goitrous condition due to an actual deficiency of 
iodine in the food material in certain regions, if it really existed. 
It would, however, explain the differences observed in the effect 
of the two types of rations mentioned above and, further, ex- 
plain the sporadic occurrence of the hairless pig malady. This 
disease occurs more often in gilts than in old sows. It is more 
likely to occur in the spring and disappear with the fall litters. 
On one farm in Wisconsin fifteen from a herd of twenty brood 
‘sows produced hairless pigs in the spring of 1917. These sows 
received a ration of flour middlings, ground oats, skim milk, 
oil meal, and some ear corn. The slop for the greater part of 
the winter contained mostly skim milk. This is a high protein 
ration and probably somewhat constipating. These same sows 
on summer pasture, with more exercise and roughage farrowed 
large, healthy litters. The high protein levels fed gilts, the les- 
sened exercise, and more constipating foods of winter are exactly 
the conditions accompanying the greater prevalence of this 
malady; and these are the more likely conditions leading to a 
disturbed assimilation or absorption of iodine. 
The hypothesis that the toxicity comes directly from the food 
materials, as distinct from having its origin in intestinal putre- 
faction, and leads to a deranged thyroid metabolism is not out- 
side the pale of possibilities. Certain saponins, as digitalin, and 
toxic substances, as ricin and abrin, are said to produce thyroid 
hyperplasia. The fact that the hairless pig malady in the north- 
west is In some cases sharply limited to certain areas, but that 
within these areas there are unaffected spots, as reported by 
Smith,? strongly suggests the possibility that toxic plants may be 
concerned in the production of a faulty thyroid metabolism and 
hairless pigs in some of these localities. 
Recently Burget’ has attempted to produce thyroid hyperplasia 
in rats experimentally. In this he succeeded through the in- 
strumentality of unsanitary conditions and high protein diets. 
Further he presents evidence to show that the enlarged thyroid 
is not produced by specific infection, a view which is in harmony 
7 Burget, G. E., Am. J. Physiol., 1917, xliv, 492. 
