The object of this investigation was to ascertain what effects, if any, were produced in the teeth of rats by an excessive meat diet. The material employed was: -

(a) A series of eight animals, which were fed on an exclusive ox-flesh diet for five months, the diet being commenced when the animals were weaned, six controls (bread-and-milk-fed) being examined from the same litters.

(b) Three rats, which were fed on an exclusive horse-flesh diet for five and eight months, the diet being commenced when the animals were about two and a half months old.

(c) A series of the second generation of meat-fed rats, thirty in number, with a like number of control subjects, the ages varying from one day to three months.

The methods of investigation were: -

I. A naked-eye examination of the size and general appearance of the teeth.

II. Grinding down the teeth, and submitting to microscopic examination.

III. Comparison of the histological appearance of the decalcified tissues. This applies to the third series.

The general results may be summarised: -

In series (a) and (b) the enamel and the dentine of the meat-fed subjects are well developed, and, with one exception, show no gross defect Two of the controls show defects similar to the exception noted. An examination of series (c) shows that the general development of the teeth in the meat-fed subjects is perhaps somewhat behind that of the controls.

It is, however, noteworthy that in the oldest animals examined - a litter of three rats - the histological appearances show no indication of retarded growth. We are not in a position to express an opinion as to the rate of eruption of the teeth. A striking feature in our observations was the extreme softness of the bones of the jaws in the meat-fed animals, and in view of this alteration in the bones it is of interest to note the relatively normal condition of the teeth.

1 G. W. Watson, L.D.S., and J. H. Gibbs, F.R.C.S.E., Journal of Physiology.