The combs of all the fowls became pale in colour, indicating anemia. The degree of pallor varied, and was not constant. In some cases it was associated with great duskiness of the comb in its most dependent parts. An examination of blood-films taken just before death from two fowls, Nos. 3 and 6, showed very striking deficiency of white blood-corpuscles.
The later history of the eight fowls may be summarised: -
(a) At the end of six months two of them were returned to the yard in apparent perfect health.
(b) Two had succumbed to acute nervous derangements at the fourth and seventh months respectively. The animals went off their food, showed symptoms of paralysis and defective co-ordination, rapidly became unconscious, and died. No gross lesions were observed at the post mortem; there was no trace of uratic deposits. The macroscopic and microscopic records are not so complete as in the later group.
(c) Of the four remaining fowls, which were subsequently observed in the laboratory of the Physiological department of the University, the chart illustrates the records of freights. Attention is specially directed to the following points: -
I. No. 4 steadily gained in weight in place of losing, as in the other cases. This subject had. throughout the course of the observation, shown a much greater tolerance of the diet than its fellows. At the post-mortem examination this fowl was found to be tuberculous.
Record of weights of four fowls fed on raw meat for fourteen to sixteen months. Nos. III., V., and VI. showed great hypertrophy of thyroid and parathyroid glands. In No. IV. these glands appeared normal; this fowl was affected with intestinal and hepatic tuberculosis.
2. While the other animals lost weight, the loss in the case of No. 6 was remarkably steady and continuous (see chart). This animal was unique in showing profound atrophic changes in the intestinal tract. This animal was fed in the laboratory throughout the whole course of the experiment.
The terminal histories are of interest. No. 3, which all along had been the most injuriously affected by the diet, was killed on the fourteenth month on account of the supervention of a third attack of paralysis. These attacks wore characterised by marked paralysis and loss of appetite, lasting about a week; they were spontaneously recovered from without any change in the regime. Fig. 1 illustrates the paralysis, and also the cutaneous disturbance present during one of these attacks. It will be observed that the paralysis involved mainly the extensors of the limb.
Fig. 1. Illustrates a paralytic attack which developed after six months' raw-meat diet, and also at later intervals (see p. 559). Note also the cutaneous disturbance.
1 Face page 660.
No. 4 remained remarkably well until the end of the thirteenth month, when it appeared ailing. It rested much and ate less. At the end of the fourteenth month it developed symptoms very similar to those of strychnine poisoning (opisthotonos, spasms, etc.), but with this distinction, that the symptoms did not appear to be aggravated by handling the animal. The terminal symptoms in this case were unlike those seen in any of the others.
At the thirteenth month symptoms of distinct paralysis (acute) were manifested, the weakness being much more pronounced on one side. The animal could not maintain itself in the sitting posture, but fell invariably to one side. The general nutrition of the animal had been fairly well maintained, and the loss of weight was not considerable.
The general nutrition of this animal was poor. Many of its feathers had gradually assumed a brown tint; the comb showed a combination of pallor and duskiness. The fowl became paretic, and it was observed that in walking the right leg was raised higher and put down more sharply than its fellows. Blood-films taken before death showed very pronounced leucopcenia.
Before passing from the consideration of the clinical picture, reference may be made to the striking absence of the clinical features of gout. The occasional lameness and increased heat in the affected limbs were the only symptoms which in any way resembled those of gout. Both the subsequent history and the entirely negative post-mortem evidences show that the attempt to induce gout was entirely unsuccessful. If any doubt exists on this point, that will be dispelled by a reference to the illustrations of Kionka, which show the presence of marked uratic deposits in the limbs of animals in which these local symptoms had been much more severe than in the author's observations. It is worthy of note that Kionka only succeeded in inducing gout in a small proportion of his cases.
An examination of the two fowls that succumbed at the fourth and seventh months respectively revealed no gross lesions. There was no trace of uratic deposits in the articulations or other tissues. The serous membranes, liver, spleen, kidneys, and heart showed no abnormality. Histologically the livers showed a moderate degree of cellular infiltration along the portal tracts and bile ducts, with considerable deposit of pigment throughout the organ. The renal epithelium contained many fine pigment granules. The spleens were not enlarged; they showed some pigment deposit. There was no trace of vascular disease in any of these organs, and their parenchyma generally presented a normal appearance. As the examination of these cases was, however, especially directed to the presence or absence of manifestations of gout, the actual records are less complete than in the larger number of cases which survived for longer periods.
No. 4 fowl, after fourteen months on raw-meat diet. The general nutrition was good (see chart). All the organs and tissues appeared healthy, with the following exceptions: -
(a) The liver was studded with small caseous-looking nodules, which vaned in size from the head of a pin to a small bean. Microscopic examination (and the application of suitable staining methods, carried out for me by Mr Richard Muir, of the Pathological Department of the University) revealed their tuberculous nature.
(d) The lowest part of the ileum, for a distance of 6 inches, showed numerous small circular ulcers. On histological examination characteristic tuberculous nodules were seen in the mucous, submucous, and muscular coats; the ulcers were produced by the extrusion of small caseous masses.
(c) The bone-marrow was unduly dark in colour, and microscopically was of a leucoblastic type. The microscopic examination of the spleen, kidneys, heart, thyroid, pancreas, and muscular system revealed no abnormal appearances.
Similarly, the examination of the spinal cord at three different levels, kindly made for me by Ur Ford Robertson, failed to reveal any indication of (a) desease of the vessels, or (b) degeneration of nerve-fibres (Marchi and Weigert-Pal methods). The systemic vessels generally appeared perfectly healthy, with the exception of one artery (sciatic), which showed a well-marked patch of endarteritis. This may have been due to a previous thrombosis.
After fourteen and sixteen months' raw-meat diet. No trace of gout was present. These fowls, unlike the former, showed some pronounced lesions. Of these the only changes common to all of them were found in the thyroid and parathyroid glands. The thyroid gland was much enlarged in the case of Nos. 3 and 6 (see Fig. 3), and enormously so in No. 5. The weights of the two glands in the last mentioned were 9.5 grammes and 3.0 grammes respectively. Histological examination showed: i. Increase in size of the vesicles, which were filled with colloid substance which stained perfectly (see Fig. 2, and compare Fig. 3).
(ii). Diminution in the intervesicular glandular tissue.
(iii). Increase in the number of cells in the wall of vesicles.
The enlarged glands in No. 5 showed well-marked haemorrhages into the vesicles. The parathyroid glands were very markedly enlarged in all three cases, more especially in Nos. 3 and 0 (see Fig. 3). Normally these glands are not visible to the unaided eye; in these three animals the glands stood out as more or less globular masses distinctly larger than a pea (see Fig. 4). Histologically the sections presented the appearance of normal parathyroid tissue.
Very striking changes were found in the bony system in two cases (Nos. 3 and 6). In No. 3 the long bones were increased in thickness, and irregular on their surface; the femora were markedly curved. On section of the long bones it was found that the marrow had almost entirely disappeared (see Fig. 5), being replaced by fairly dense tissue. On microscopic examination the appearance was remarkable (see Fig. 71). The marrow proper was replaced by a non-cellular tissue presenting some of the characters of an osteoid tissue; a similar appearance was seen in the outer part of the bone (see Fig. 7). The large masses apparently represent much altered Haversian spaces, the appearances being due to an infiltration of some substance which stains pink with picro-carmine. Chemical examination showed a great increase in the proportion of organic matter. The appearances in the bone in No. 6 were of a similar character, but less pronounced. The marrow in No. 5 appeared unusually soft in consistence and dark in colour. It was not submitted to microscopic examination.
Fig. 2. - Thyroid Gland after 14 months' raw-meat diet. ( x 50.) Cf. Fig. 3. Observe - i. The increase in size 1 if the vesicles. ii. The increased thickness of wall of vesicles. iii. The disappearance of the intervesicular glandular tissue.
Fig. 3. - Thyroid Gland from normal Fowl. ( x 50.) Cf. Fig. 3.
i. The size of the vesicles. ii. The thickness of walls of the vesicles iii. The large amount of intervesicular glandular tissue.
Fact page 562.
No uniform lesions were present; the organs were for the most part normal. The following lesions were, however, noted: -
1. The intestinal tract in No. 5 showed very pronounced atrophic changes.
2. The duodenum in Nos. 5 and 3 was dilated.
3. The liver in No. 6 showed great amount of pigment.
4. The heart in No. 3 appeared to be hypertrophied.
The systemic vessels throughout showed no indications of disease of any of their coats; the vessels in the muscular system showed no abnormal appearance; and the same has to be said of the vessels in the spinal cord. There was no trace of degeneration of the nerve-fibres in the cord; in one section in No. 6 some minute capillary haemorrhages (recent) were present in the grey matter.
The points to which attention is specially directed are the hypertrophy of the thyroid and parathyroid glands in all the three healthy fowls, and to the freedom for such enlargement in the tuberculous subject. These remarkable changes in the thyroid and parathyroid cannot, it seems to me, be looked upon as an accidental circumstance void of significance on the dietetic regions in vogue. The hypertrophy of these glands is interpreted as the result of the raw-meat dietary. The recent work of Hericourt and Richet, on the special value of raw meat as a curative agent in tuberculosis suggests that in the tuberculous fowl the excessive meat diet was made use of to neutralise the tuberculous toxaemia.
The negative features of interest are (a) the entire absence of uratic deposits; (b) the absence of renal disease, and (c) the healthy state of the blood-vessels throughout the system. These last two negative features have significance in relation to the commonly accepted view that a nitrogenous dietary leads to general vascular and renal disease.
' From stained sections kindly made by Dr Carnegie Dickson, of the Pathological Department of the University, it is seen that the large dark areas in the section represent concentric laminae of imperfectly developed bone, the older laminae staining faintly, the younger ones deeply. The Haversian spaces are reduced in size, and as the spaces become narrowed the vessels are obliterated. The spaces are void of osteoblasts and osteoclasts, and contain simply fat and an artery and vein.