(An Experimental and Clinical Study).
The object of this paper is to record the clinical and pathological appearances observed in an experimental research on prolonged feeding of fowls on a diet of raw meat. The main facts to which attention will be directed are: -
The absence of any indications of gout (uratic deposits).
(a) The variety in the clinical and pathological features observed in the different subjects.
(b) The lesions in the thyroid and parathyroid glands and bone-marrow.
(c) The very favourable manner in which one fowl affected with well-marked tuberculosis was influenced by the diet.
This research was begun with the object of confirming or otherwise the interesting research of Kionka on avian gout. It may at once be stated that the results obtained did not confirm those described in Kionka's record; the experiment was unsuccessful so far as the induction of gout was concerned. This negative result is of itself of much interest; the interest is enhanced by the changes incidentally observed in the thyroid glandular system, the bone-marrow and other tissues in the non-tuberculous fowls, and by the distinctive character of the reactions in the tuberculous subject.
The observations were begun on 10th March 1900, and consisted in feeding eight fowls, six hens and two cocks, on a diet of raw lean meat and water. Four of the fowls were a year old, and four were just under two years of age. The subjects were of a common farmyard stock. For the first six months seven of the fowls were kept in the country, the animals being confined in a hen-run by the side of a wall, the floor being composed of natural soil. This enabled the animals to have a fair amount of exercise, and also to supplement their diet by grit and other material from the soil. The remaining fowl, a cock, No. 6, was kept in an iron cage in the Physiological Department of the University during the whole course of the observations.
The fowls were fed on raw lean ox-meat and a liberal supply of water. About the third month an attempt was made to substitute horse-flesh (which had been cooked for purpose of preservation), but this was abandoned, partly on account of the difficulties in obtaining the meat, and partly because this form of diet was not readily taken by the animals. Some sand and small grit was supplied from time to time. The observations continued until July 1901, a period of sixteen months.
For the first few months the fowls took the diet greedily, the average amount of meat taken by each fowl being rather more than three-quarters of a pound per diem. In the later stages the appetites were not so keen, and at intervals the animals ate much less heartily, this defect in the appetite being usually associated with other Symptoms. The hens appeared to thrive all right for the first few weeks, but about the sixth week slight indications of ill-health set in. This was manifest in a very slight and just perceptible lameness, which later became more pronounced in one of the younger hens (No. 3) and one of the older birds. This tendency to lameness remained more or less throughout the whole course of the observation, but in the case of No. 4 it was not manifest after the fifth month. On several occasions when the lameness was distinct there was a manifest increased heat in the affected limb. A little later the fowls showed a greater tendency to sit, and would rest on the ground for much longer periods than was natural. They roosted each night.
1 Chalmers Watson, Medico-Chirurigual Transactions, London, 1904.
At the outset of the observations the number of eggs markedly increased, this increase persisting for about four weeks, when a gradual diminution set in, terminating in complete cessation. The yolks of the eggs became particularly pale; a baked custard and a dish of scrambled made with them were perfectly void of colour, and appeared more like thick curds. After four months of the diet the eggs were not edible, on account of decomposition-changes which were revealed in the process of cooking.
In about six weeks from the outset the feathers of some of the birds became disarranged. The tails drooped, and the birds appeared out of sorts generally. Several of the fowls lost many of their feathers; one fowl was almost denuded of its feather covering, the loss being hastened by its companions picking off the feathers. About this time the fowls showed a marked tendency to pick the lime off the walls, and continued doing so for some time. The cutaneous disturbance is shown in the illustration (Fig. 1).