EXPERIMENTAL SCURVY
There is no mention whatsoever of scurvy in animals previous to 1895,
when Theobald Smith wrote: "When guinea-pigs are fed with cereal (it has
been observed for some years in this laboratory), with bran and oats
mixed, without any grass, clover, or succulent vegetable, such as
cabbage, a peculiar disease, chiefly recognizable by subcutaneous
extravasations of blood, carries them off in from four to eight weeks."
Smith did not pursue the subject further.
Coincident with the appreciation of the value of experimental methods,
one would have expected attempts to produce scurvy in animals. The
disorder had been recognized for a great many years, the fact that it
was occasioned by a dietary deficient in fresh food was widely known, so
that it would seem natural for clinicians or laboratory workers to have
tried to induce the disease in animals by a similar restricted diet.
There is, however, no suggestion of such an experiment in the voluminous
literature on scurvy. The explanation of the neglect of an experimental
study of scurvy appears to be that this was considered a disorder which
required little investigation--its etiology, its prevention and its cure
seemed thoroughly understood. It is strange that the mere fact that such
a severe disturbance responded, as if by magic, to the administration of
simple foodstuffs should not have awakened curiosity as well as wonder,
and stimulated inquiry into the nature and significance of the curative
agent.
In 1903 Bolle published the results of experiments on guinea-pigs which
had been fed for various periods on raw or sterilized milk. He reported
that the animals developed a marked fragility of the bones, varying in
intensity in proportion to the degree of heat to which the milk had been
subjected. These changes Bolle interpreted as typical scurvy, but it is
difficult to decide whether the disorder was actually true scurvy, in
view of the indefinite description of the bone lesions.
Bartenstein repeated Bolle's work and described in detail the changes in
the bones. From his work we learned that it was of little moment whether
the animals were fed raw or sterilized milk--their nutrition failed
within about the same length of time, and they died within a month. The
chief pathologic change was a marked fragility of the bones, leading to
spontaneous fractures, or to breaking of the bones in the course of
ordinary manipulation. Bartenstein described the disorder as "beginning
with the degeneration of the marrow, and secondarily leading to an
atrophy of the bone due to increased absorption and deficient new
formation of bone, especially at the endochondral lines of ossification.
As the result of the osteoporosis, spontaneous fractures occur without
noticeable hemorrhagic diathesis." He found a deficiency of calcium in
the bones of animals suffering from even a mild degree of this disorder.
Hart and Lessing are of the opinion that we cannot accept Bartenstein's
diagnosis of scurvy. They compare this disorder to that described by
Ziegler as "osteotabes infantum," in which there is a more or less
pronounced "jelly marrow" which has replaced the lymphoid cells in
scattered areas. They sum up their analysis of the question with the
statement that "the primary marrow changes in the diaphysis, the marked
lacunar absorption by osteoclasts, the absence of subperiosteal
hemorrhages, do not indicate typical scurvy." Schmorl produced
comparable lesions in dogs and came to the conclusion that the disorder
was one "very similar" to scurvy but not identical with it, the
essential difference being that in all animals there was a most marked
absorption of bone by osteoclasts.
Similar results were obtained by others. In 1904 Peiper and Eichloff
attempted to produce scurvy in dogs by means of a diet composed
exclusively of raw or of sterilized milk. The following year we find a
report by Esser of feeding goats on sterilized milk. None of these
studies hits the mark; a condition of fragilitas ossium was produced
rather than typical scurvy.
In 1907 the first systematic and convincing experimental study of scurvy
appeared. In this year Holst and Froelich published a preliminary
account of their classic work, undertaken in an endeavor to fathom the
nature of "ship beriberi," a disorder which disabled so many of the
sailors in the Norwegian navy. We must remember that until recently
attention has been focussed on the infectious diseases, and little
thought given to the investigation of nutritional disorders. Although
experimental investigation in this field may be stated to have been
initiated by this work, it in turn had been stimulated by a conception
of dietary diseases which had just begun to be realized. This new
viewpoint was the result of the work of Eijkman. As has been mentioned
in considering the pathogenesis of human scurvy, Eijkman demonstrated
that hens developed polyneuritis, a disease resembling beriberi, when
fed on polished rice, and that the simple change to a diet of unpolished
rice, or the addition of rice polishings to the dietary, sufficed to
protect or to cure. This work had been repeated and substantiated. It
was evident to those who considered the question that the old lines of
thought in regard to food and dietetics inadequately explained
remarkable phenomena of this kind. It was also clear that nutritional
disorders were subject to experimental investigation in a way similar to
the infectious diseases, which were absorbing the interest of the
various laboratories. It is unnecessary to review the rapid rise of
investigative work in this field. It may be stated, in general, that
during the past few years the investigations of scurvy have become so
numerous that an established research technic may be said to have
developed in connection with its study.
Attempts have been made to produce scurvy in various animals, but it has
been brought about regularly only in the guinea-pig and in the monkey.
Experiments on the dog are as yet too few to justify our regarding this
animal as definitely available for this study. The nutrition of rats,
mice, rabbits, hogs, pigeons, fowl, receiving a diet identical with that
which regularly occasions scurvy in guinea-pigs, either progresses
normally or a state of malnutrition develops which cannot be identified
with scurvy. Recently Hart, Steenbock and Smith have reported that
cattle can be reared to maturity on a diet which will produce scurvy in
the guinea-pig in four to five weeks. We are therefore confronted with
the remarkable and inexplicable phenomenon, a fact concurred in by
almost all investigators, that a diet induces either normal nutrition or
malnutrition, according to the experimental animal employed. A diet of
polished rice, or other decorticated grain, will lead to the development
of scurvy in the guinea-pig, to polyneuritis in the pigeon or fowl, or,
according to Holst and Froelich, to a combination of these disorders in
the hog.[35] The basis of these divergent results cannot be surmised,
and is worthy of the most thorough investigation. It may well be that
the elucidation of this problem--for example, why we are able to bring
about scurvy in the guinea-pig but not in the rabbit, will shed light on
the pathogenesis of this disorder. Are we to conclude that some of these
animals have the power to synthesize the vitamine whereas others must
depend upon the food for it, or are we to presuppose an ability to
maintain normal life and function without any or with a minimal amount
of this vitamine? The difference between these two groups, the
susceptible and non-susceptible animals, probably is not as absolute as
we have been wont to regard it. Recently Harden and Zilva have shown
that although rats are able to thrive on a diet free from antiscorbutic
vitamine, they show an appreciable gain in weight when this factor is
added to the dietary. If such be proved to be the case, we must regard
the non-susceptibility of the rat, the rabbit, etc., as relative rather
than absolute.
[35] Hogs fed on 1.5 kg. of rye bread and 0.5 kg. of meat heated to 100°
or 110° C. for a half hour showed the hemorrhages, loosening of the
teeth and affections of the gums characteristic of scurvy, as well as
the paralysis and neuritis typical of polyneuritis.
From time to time a doubt has been raised as to whether we should accept
guinea-pig scurvy as the counterpart of human scurvy. This question can
be answered only by comparing the disorder in the one species with that
in the other--as to mode of production, pathology, symptomatology, means
of cure and all other phenomena. Viewed from these standpoints it is
found that in almost every respect the disorder is identical in man and
in the guinea-pig. The outstanding distinction is the difference in the
length of time elapsing before the development of symptoms. In the child
or in the adult it takes about six months of the deficient diet before
clinical symptoms are manifest and a diagnosis can be established; in
the guinea-pig the disorder can be recognized two weeks after
restricting the diet. In the one instance we seem to be dealing with a
nutritional disorder which is chronic or at least subacute, and in the
other with a markedly acute condition. This distinction is open,
however, to certain qualifications. In the first place, we must consider
the duration of life of the two species, the comparatively short span of
the guinea-pig compared with that of man. It must be borne in mind,
furthermore, that the guinea-pig is placed on a diet absolutely devoid
of all antiscorbutic vitamine, whereas this rarely obtains in human
beings. For example, the diet which is most markedly scorbutic for
infants is the "malt soup" previously mentioned, but even this food
contains an amount of the antiscorbutic factor which is not negligible.
But after taking these differences into consideration, it is
nevertheless evident that the guinea-pig is far more sensitive to scurvy
than man. This does not indicate that the guinea-pig is an unsuitable
experimental animal, any more than the fact that the pigeon is more
susceptible to polyneuritis than man indicates that it is unsuited to
investigations of beriberi. It merely prevents our carrying out delicate
quantitative experiments, and cautions against drawing too finely-spun
deductions. In all nutritional investigations it should never be
forgotten that conclusions drawn from experiments on animals are merely
provisional, and must await substantiation on man, and, furthermore,
that where differences in reaction are noted, the clinical data should
be accorded full consideration.
=Pathogenesis of Guinea-pig Scurvy.=--From a pathogenetic point of view
guinea-pig scurvy and human scurvy show remarkable points in common. Any
diet that leads to the development of scurvy in man likewise brings it
about in the guinea-pig, and contrariwise, any food which cures the
disorder has the same beneficent effect on both species. This similarity
extends so far that, as will be shown in the chapter on antiscorbutics,
the relative potency of the various foods is approximately the same for
man and for the guinea-pig. The parallelism generally is striking. The
dietary which has been commonly employed in experimental scurvy has been
that first suggested by Holst and Froelich, namely, oats, hay and water.
Recently, however, this dietary has been enlarged in order to make it
more complete, so as to include adequate protein, water-soluble and
fat-soluble vitamine, and inorganic salts. To this end the group of
workers at the Lister Institute (Chick and co-workers, Harden and Zilva)
place their animals on a basal diet of one part of crushed oats and two
of wheaten bran, and a daily ration of 50 to 60 c.c. of milk autoclaved
for one hour at 120° C. This milk still retains a small amount of
antiscorbutic vitamine. Cohen and Mendel have employed, apparently with
good result, a "soy bean cracker," containing soy bean flour which has
been heated for 30 minutes at 15 pounds' pressure (120° C.), 3 per cent.
of sodium chloride, the same percentage of calcium lactate and of dried
brewers' yeast, and raw milk sufficient to supply 5 per cent. of
butter-fat.
The use of raw milk was introduced by Jackson and Moore, and adopted by
McCollum and Pitz and again by Pitz in a series of interesting
experiments. The milk was given _ad libitum_. The results of these
investigations were puzzling at first, until it was shown by Chick, Hume
and Skelton that the dietary on which they were based contained a
fundamental error which accounted for their lack of consistence.
Although milk is not rich in the antiscorbutic factor, it possesses it
in moderate degree, so that the outcome will be quite different
according to whether a guinea-pig takes, for example, 50 c.c. or 100
c.c. daily. It is quite evident, therefore, that a food of this kind
cannot be offered _ad libitum_, and that if this rule is not observed,
most disconcerting results will follow.[36] This basic error in framing
the dietary has made it impossible to accept the deductions of these
authors. The conclusions of McCollum and Pitz are so striking and have
led to such wide discussion, that they require consideration, in spite
of the fact that the error in the dietary is now recognized. These
authors found that the cæcum of their animals was greatly distended with
putrefying fæces. As the cæcum is extraordinarily large and delicate in
this species, they drew the deduction that the development of scurvy in
the guinea-pig was due principally to the retention of fæces. "An
impacted cæcum, the seat of putrefaction, may cause injury to the cæcal
wall, sufficient to permit the invasion of the tissues by bacteria, or
the animals may perhaps be injured primarily by the absorption of toxic
products of bacterial origin." Accessory dietary factors or vitamines,
according to this theory, are supposed to play no part in the disorder,
and antiscorbutics, such as orange juice, are considered to owe their
efficacy mainly to their laxative properties, and to be replaceable by
other laxatives such as phenolphthalein or oleum petrolatum. The
efficacy of orange juice is supposed to be due to its content of
citrates, and to be replaceable by what was termed "artificial orange
juice," a mixture composed of the various salts, citric acid and
sucrose, in the proportions in which they are found in the natural
juice.
[36] A guinea-pig requires about 80 to 100 c.c. of fresh milk per diem
to protect it from manifest scurvy, if this constitutes its sole
antiscorbutic quota. There is, however, a great difference in the amount
of milk which individual animals consume, so that if we furnish it _ad
libitum_ our results will be irregular, one animal developing scurvy and
another remaining well, according to individual appetite. Frequently
guinea-pigs take very little milk at first, learning gradually to drink
more and more, so that it comes to pass that only after some weeks, if
at all, they take sufficient to afford protection. Under these
circumstances, if any addition is made to the dietary after the
experiment has progressed, the lack of development or cure of the scurvy
may mistakenly be attributed to this newly introduced factor, whereas,
in point of fact, it is due to an increased consumption of milk.
These reports stimulated renewed interest in experimental scurvy,
suggesting new aspects, and therefore directing attention to points
requiring investigation. There were no data at hand on the consistency
of the contents of the bowel in guinea-pigs, so that it was necessary to
make appropriate observations in normal and in scorbutic animals. It
was soon reported by various workers, Rappleye, Cohen and Mendel, Hess
and Unger, and others, that there was no definite relationship between
the occurrence of scurvy and impaction of the cæcum. In Fig. 8 we see
portrayed the stool output of a guinea-pig during the period in which it
was developing scurvy, and during a subsequent period when it was being
cured by means of orange juice. It is clear that there was no
significant variation in the output during these divergent periods. A
similar conclusion was arrived at by those who examined the cæcums of
animals postmortem. Cohen and Mendel write: "Summarizing our experience
with nearly one hundred scorbutic animals, we conclude that actual
impaction of the fæces in the cæcum occurred in about one-quarter of the
cases, and visible damage to wall, _i.e._, congestion or hemorrhage, or
impaction, or both, was found in perhaps half of the cases. It should be
noted that this statement covers all the diets we have tried." We concur
in this conclusion. Not infrequently we found the cæcums of markedly
scorbutic pigs to contain semi-fluid fæces, the consistency of its
contents depending on the character of the diet, quite apart from its
adequacy and lack of the antiscorbutic factor. For example, a diet rich
in milk, containing 100 c.c. or more, led to the formation of rather
solid fæces; if oats were added to the milk diet the fæces in the cæcum
were found to be still more solid, and this portion of the gut more
often impacted. This condition could be detected by palpation even
during life. Just as we encountered scorbutic animals on an oat, hay and
water diet, who had semi-fluid fæces in the cæcums, so we met with
others which were on a milk diet, and showed no signs of scurvy,
although their cæcums were impacted with fæces of a putty-like
consistence. Guinea-pigs do not seem to be able to tolerate a diet
containing a large quantity of the fat of cow's milk. Such a diet leads
to impaction of the large intestine resulting in death, but does not
induce scurvy. Jackson and Moore produced a condition of this kind by
feeding pigs with cream containing 26 to 28 per cent. fat. "In every
case," they write, "the large intestine was distended with light
mustard-colored semi-solid fæces." This pathological condition is not
understood, but is quite distinct from scurvy, and remarkable in view of
the fact that the milk of the guinea-pig contains as high as 25 per
cent. of fat. It is an interesting illustration of the marked biological
difference in the butter-fat of various species.
[Illustration: FIG. 8.--Shows a period with the development of scurvy,
and one where it was cured by giving orange juice. It will be noted that
there was no marked constipation while the animal had scurvy. During a
period of a few days the amount of stool was scanty, corresponding to
the decreased intake of oats and hay on the days preceding. Broken line
represents clinical course of scurvy.]
Nor was it found, as McCollum and Pitz claimed, that antiscorbutics were
replaceable by laxatives in the diet. Without entering into the details
of this aspect of the subject, which will be considered in the chapter
on symptomatology, it may be stated that attempts to prevent the
occurrence of scurvy or to cure it by means of laxatives invariably
failed. Chick, Hume and Skelton, as well as Hess and Unger, gave oleum
petrolatum to a series of pigs without the slightest favorable effect.
Hart, Steenbock and Smith recently reported that they had administered 1
c.c. of this oil on alternate days to one series of pigs, and 2 mg. of
phenolphthalein on alternate days to another series, without relieving
the scurvy. Cohen and Mendel, in order to test the adequacy of their
diet as to roughage, supplemented it with additions of considerable
filter paper and sawdust, "without averting the appearance of scurvy."
It is evident, therefore, that constipation does not play an essential
rôle in the pathogenesis of scurvy in the guinea-pig, and that
antiscorbutics are by no means synonymous or interchangeable with
laxatives. These results accord with observations on infantile scurvy.
=The Pathology.=--The pathology of guinea-pig scurvy is essentially that
of human scurvy. Hemorrhages and separations of the epiphyses or
fractures of the long bones dominate the macroscopic picture. The
hemorrhages are found rarely in the gums, but are common about the
joints, in the muscles of the jaw or in those of the hind legs. They may
be subcutaneous and appear as bluish discolorations at various parts of
the body, especially if the disorder has resulted in death or if
infection has been superadded. On stripping the skin we often note
hemorrhages in the intercostal muscles, and beading of the ribs at the
site of the costochondral junctions, least marked in the upper and in
the floating ribs. This has been frequently described in connection with
guinea-pig scurvy; its similarity to the rosary of human rickets has
been drawn attention to recently by Jackson and Moore. It should not be
regarded as "pseudo-rhachitic," but as typically scorbutic, from a
microscopic as well as a macroscopic viewpoint. On closer examination a
yellowish-white transverse line may be seen at the epiphyseal junction
of the ribs, and frequently some subperiosteal hemorrhage. Beading of
this character has been reported by Ingier also in the "snuffles" of
hogs and as the result of trauma. A similar enlargement of the chondral
junctions of the sternum may be found on examining its posterior
surface.
_The joints_ of the body always show some changes. The epiphyses are
enlarged to a variable degree, resembling the epiphyses typical of human
rickets. As in infants, this change is met with most commonly at the
wrist joint, involving the ulna and the radius. The knee-joint is
likewise often involved, especially the ends of the tibia; the elbow,
ankle, and the shoulder may also show an articular swelling of the
bones. About these joints hemorrhages in the subcutaneous tissues may be
seen, or edema extending along the extremities. Not infrequently a
fracture of one of the long bones is found, which may or may not have
been diagnosed during life. The common site of fracture is the lower
part of the tibia or fibula. Much more frequent than fractures are
separations of the epiphyses, which long since have been recognized as
typical of infantile scurvy. Even gentle handling in the course of
performing the necropsy may occasion a lesion of this kind--of the tibia
at the knee, of the radius or ulna at the wrist, or indeed at any of the
epiphyseal junctions. The infracted ends occasionally may be seen held
insecurely by a delicate band of periosteum. The shafts of the bones are
brittle, rarefied, and easily broken.
On opening _the chest_, slight hemorrhages may be noted in the
pericardium and in the visceral and costal pleuræ. The heart is
frequently enlarged, and the pericardial sac contains an excess of
serum; the right ventricle, however, is not found disproportionately
hypertrophied. Pneumonia is met with very frequently and constitutes a
common terminal infection.
On opening _the abdomen_ we may note subperitoneal hemorrhages of the
muscular wall or of the coils of intestine. The liver and spleen are
generally normal, as is the pancreas. The kidney frequently shows minute
hemorrhages beneath the capsule and on section.
_The adrenals_ not infrequently are large. This fact was first brought
out by Rondoni and Montagnani, and is of added interest in view of its
confirmation by McCarrison as well as by LaMer and Campbell. Its
significance is discussed at length in the consideration of the adrenal
gland in human scurvy. In view of the fact that fasting leads to a
similar hypertrophy, and that guinea-pig scurvy frequently is
complicated by fasting, these observations should be extended. In all
investigations of this kind, bacterial cultures should be taken of the
adrenals, or other organs, to be certain that there is no complicating
infection.
There have been no reports as to the effect of scurvy on the size of the
testicles, ovary, thymus, thyroid or parathyroid glands in the
guinea-pig, such as have been made by McCarrison in relation to avian
polyneuritis.
_The alimentary tract_ occasionally shows macroscopic changes similar to
the lesions found in man. The entire canal is frequently very empty,
especially the stomach and the small intestine, due to the lack of
appetite for some days previous to death. In the stomach we may find
areas of congestion or numerous small superficial ulcers surrounded by
congestion and covered with mucus; occasionally these ulcers are
somewhat larger and deeper. The larger ulcers are more frequently
situated in the first part of the duodenum, often proximal to the
papilla of Vater. Holst and Froelich described this lesion in one of
their early communications. More common than ulceration of the duodenum
is a diffuse congestion of its upper part. This lesion is of note
because it has been described frequently in the protocols of human
necropsies, and is found in beriberi, in avian polyneuritis, and in
pellagra in man. Its significance is unknown, and has indeed never been
discussed.
Lower down in the bowel there are occasionally areas of congestion and
ulceration, but no section seems particularly predisposed to these
lesions. The contents of the bowel, especially of the cæcum, as
mentioned above, depend more on the character of the food than on the
existence of scurvy. If the diet has consisted of milk and oats, the
cæcum will be found full and perhaps impacted, whereas if hay and oats
have been fed, the cæcum will be less full and its contents semisolid.
In view of the fact that many of the animals have taken very little food
for some days previous to their death, it will be well to describe
briefly the macroscopic picture of _simple starvation_ in guinea-pigs.
When guinea-pigs are given only water they live about one week; if
orange juice is added to this water diet they succumb a little later to
starvation. Under all these conditions the striking pathologic
change--absent in scurvy--is edema. It is true that the limbs may show
slight edema in scurvy, and that the pericardial and the pleural sacs,
and even the peritoneal cavity, occasionally contain a small quantity of
serum, but it is comparatively an insignificant amount. Moreover it is
difficult to decide to what extent this edema is due to scurvy, and to
what extent to starvation. In typical starvation, on the other hand,
such as occurs on the limited diets enumerated above, we find marked
subcutaneous edema, sometimes a true anasarca, and frequently also
ascites. We are reminded of the "war edema" and its frequent association
with starvation. Another distinction between the two conditions is the
fact that the marrow in starvation is yellow and not red as in scurvy.
In passing, it may be mentioned that the ascites was greater when orange
juice had been given than where the animal received only water.
In perusing the literature but one study has been noted on _the effect
of a scorbutic diet on the foetus_. This investigation was carried out
on a large series of guinea-pigs by Ingier (1915). The following
comprise her conclusions:
"1. Pronounced cases of Barlow's disease may be produced in the foetus
as early as ten to fifteen days after the commencement of dieting
pregnant guinea-pigs with oats and water. There are wide individual
variations. The scorbutic changes in the skeleton are greatest in the
earlier embryonic stages. The foetuses of that period, with
practically no exceptions, die and show marked traces of impeded growth.
"2. Foetuses from the later period of pregnancy are born alive, and
apparently fully developed, with comparatively slight changes in the
osseous system.
"3. Even a short extension of the period of extra-uterine dieting on
milk from scorbutic mothers, and later on oats and water, is sufficient
to change the latent scurvy into a highly-pronounced case.
"4. The foetus cannot be kept alive longer than the adult animal,
about twenty-eight days, either by intra-uterine dieting alone or by
combined intra- and extra-uterine dieting.
"5. The mothers show signs of the disease at an early period and are
more severely attacked than non-pregnant animals. Death also occurs
comparatively often in the first period of gestation."
In these experiments intra-uterine fractures, premature births and
still-born litters are frequently mentioned. This suggests naturally an
inquiry as to whether similar occurrences have been observed in human
scurvy. In considering the pathogenesis of human scurvy, we have
remarked on the meagreness of the data on this most interesting aspect
of this disorder. In view of the similarity between human and guinea-pig
scurvy, we should expect not only miscarriages and still-births to
result, but cases of congenital scurvy, especially of the latent or
rudimentary type.
=Scurvy Has Been Induced Also in the Monkey.=--The most extensive
investigation of this kind is that of Hart and Lessing, who brought
about scurvy in several young Macaci Rhesi which had been fed for some
months on boiled condensed milk with the addition of cooked rice and
pig-nuts. Typical scurvy resulted in all but one instance, and in this
case an old animal was used and a different pathological picture
developed. These experiments require brief reviewing, as the clinical
signs and gross pathology in monkeys differ somewhat from those
encountered in guinea-pigs, and particularly as these distinctions
render scurvy in monkeys and in infants practically identical.
Apart from general listlessness and lack of activity, the first sign is
hemorrhage of the gums, the characteristic sign of infantile scurvy.
This is stated to be constant; in the guinea-pig it is most exceptional.
Another sign characteristic of infantile scurvy is the subperiosteal
hemorrhage, which in the guinea-pig may be found as a small effusion
near one of the larger joints or the costochondral junctions, but in the
monkey consists of large effusions, similar to those described by
Barlow. Subperiosteal hemorrhages of the cranial bones were constantly
seen, and not infrequently involvement of the scapula and of the
maxilla. Hemorrhage into the orbit leading to exophthalmos and to
hemorrhagic discoloration of the upper lid--a lesion not infrequent in
human scurvy--is also described; in guinea-pigs we have met with
exophthalmos only in two instances. In all other respects scurvy in the
monkey resembles that in the guinea-pig, even to the extent of the
scorbutic rosary of the lower true ribs. Hart and Lessing describe the
presence of the "white line" of Fraenkel, which is referred to at length
in treating of the symptomatology of human scurvy. This is a shadow,
seen by means of the X-ray, traversing the long bones near their
epiphyses--a definite "shadow band" associated with a narrow light zone
lying just beneath it. This "white line" has been noted likewise by
Talbot, Dodd and Peterson in the scurvy of monkeys.
=Microscopic Pathology.=--Turning to the microscopic pathology, we find
that the changes are similar to those described elsewhere in connection
with human scurvy. It will be unnecessary, therefore, to give more than
a general survey of the typical alterations. Little has been added to
the description of lesions so carefully depicted in the first report of
Holst and Froelich (1907). The bone marrow at the ends of the diaphyses
in proximity to the epiphyseal junction loses its normal lymphoid
character and is replaced by a reticular or fibrillated substance, the
so-called "framework" marrow (Geruestmark of Schoedel and Nauwerk)
containing a homogeneous mucoid tissue and only a few osteoblasts and
marrow cells. The number of blood-vessels is considerably reduced and
fresh hemorrhage or blood pigment is frequently seen. The osseous tissue
itself shows marked changes, corresponding to the rarification and
brittleness noted on gross examination. The osseous trabeculæ are fewer
in number and those which remain are slender and irregular, and
frequently appear as isolated islets. The cortical substance also
becomes very thin. There are marked alterations in the intermediate
cartilages, especially of the ribs.[37] Instead of the cells being
arranged in orderly rows, they are irregularly placed, and frequently
greatly reduced in size and number. The bone trabeculæ on which they
abut are not well formed or of equal length, and do not present an even
and transverse plane, but are misshapen, small, so that the line of
junction with the cartilage is zigzag. In cases of marked scurvy the
junction may be entirely disorganized and deformed, showing fractures of
the rarefied bone and hemorrhages in the neighborhood. This leads
frequently to a macroscopic deformity of bone, a bulging of the surface
at the costochondral junction--the scorbutic "beading" or "rosary" of
the ribs. Recently Delf and Tozer have described these changes,
classifying them as those occurring in "incipient," "definite," "acute,"
"chronic definite," and "chronic acute" scurvy. Fig. 9 shows these types
in diagrammatic form. In this figure we see how varied may be the
manifestations of this nutritional disorder, according to whether it has
existed for a shorter or a longer time; in some instances the picture is
very puzzling. The "incipient scurvy" corresponds to what we have termed
clinically "latent scurvy" in infants, a condition which cannot be
diagnosed and is manifested merely by a faulty nutrition which responds
promptly to the addition of an antiscorbutic to the diet. There have
been no histologic examinations in man at this incipient stage, but we
may infer that they are similar to the bony changes found in the
guinea-pig. When the scurvy has become chronic in an animal which has
lived for months on a quota of antiscorbutic food sufficient to preserve
life but insufficient to prevent the development of scurvy, we find a
microscopic picture at the costochondral junction differing widely from
that seen in the acute stage. Not only are the columns of cartilage
cells represented merely by misshapen vestiges, but an ossified band
(Fig. 9) is seen at the junction. It is probable that this is
frequently the cause of the marked cessation of growth which has been
described in connection with this type of scurvy in infants. Delf and
Tozer interpret this ossified band at the junction as "an attempt to
strengthen the junction in an abnormal manner, the normal process having
broken down." If the animal is again deprived of antiscorbutic food the
ossified band breaks down, the junction becomes deformed and
disorganized, and a condition of "chronic scurvy (acute)" is stated to
have developed.
[37] These changes are not found in every specimen, so that in order to
be able to exclude scurvy definitely, it is necessary to examine a
considerable number of ribs; several may be normal, only one or two
showing the characteristic microscopic changes.
[Illustration: FIG. 9.--Diagrammatic representation of guinea-pig scurvy
(copied from Delf and Tozer by the courtesy of the Cambridge Press).
1. Diagram of normal rib-junction.
2. Diagram of rib-junction to illustrate "Incipient Scurvy." This
rib-junction is very nearly normal, but shows what may be regarded as
the first recognizable signs of the onset of the disease; these are:
(_a_) An appearance of general abnormality (when compared with the
normal). (_b_) Unevenness of the junction and slight disorganization of
the rows of cartilage cells. (_c_) Shortening of the length of the rows
of cartilage cells. (_d_) Shortening, and decrease in number of the
trabeculæ. (_e_) Increased amount of blood in the marrow cavity.
3. Diagram of rib-junction to illustrate "Definite Scurvy." Histological
signs vary considerably in these cases (according to the severity of the
disease), and may approach in appearance those characteristic of the
"Acute" condition. The rows of cartilage cells may be almost normal, but
are more often noticeably shortened and usually somewhat disorganized or
arranged in circular groups. The trabeculæ are usually about half the
normal length and have a truncated appearance. The junction as a whole
may present an uneven, slightly disorganized appearance and there is
sometimes a certain amount of macroscopic deformity.
4. Diagram of rib-junction to illustrate "Acute Scurvy." In these cases
the junction and rows of cartilage cells are often completely
disorganized, causing a marked macroscopic deformity of the bone. The
bone of the shaft is frequently fractured. The marrow is no longer in
contact with the edge of the junction and the space is filled with a
mass of connective tissue; this is very characteristic in cases of
fracture. A condition in which the trabeculæ have almost disappeared and
the rows are much shortened is also found in "Acute Scurvy," in those
ribs in which no fracture of the shaft has occurred; usually, however,
there is little or no ossification across the junction. There is
frequently hemorrhage into the marrow cavity.
Diagrams 5 and 6 illustrate types of "Chronic Scurvy."
5. May be described as "Chronic Definite Scurvy." The rows are much
shortened but not disorganized and an ossified band extends across the
junction.
6. May be described as "Acute Chronic Scurvy." The junction is deformed,
and the rows are very disorganized; the trabeculæ have disappeared and
an ossified band extends across the junction. There is no connective
tissue to be seen and no existing, or recent, fracture.]
It has been noted by many investigators that _changes in the teeth_ take
place in the course of scurvy. They become somewhat yellow and lose
their glistening appearance, and occasionally break off. The molars
commonly become loosened, so that they can readily be removed from their
alveolar sockets; less frequently this is true of the incisors. Until
recently, however, this subject has not been studied in detail, and no
significant histologic changes in the teeth have been described. Jackson
and Moore showed that with marked changes in the teeth there was often
"great dilatation of the veins in the pulp attended by more or less
hemorrhage into the pulp," and that "in guinea-pigs fed on oats and hay
there was almost complete necrosis of the pulp of the incisor teeth,
also more or less necrosis in the pulp of the molars."
Recently an intensive study of this subject has been made by Zilva and
Wells, which is of special interest because it describes the first
beginnings of these lesions, and particularly because we have no
knowledge whatsoever of the dental changes which occur in human scurvy.
These investigators found a fibroid degeneration of the pulp of the
teeth, a pulpar fibrosis. "It is clear at once," they write, "and it is
an important fact that no trace of cellular organization, no trace of
cell nuclei, no trace of interstitial cement substances can be found
anywhere. Nerves, cells, blood-vessels, and odontoblasts have all shared
the process of fibrication and are no longer recognizable." These
radical changes in the teeth, brought about by a deficiency of
antiscorbutic vitamine, were demonstrated not only in guinea-pigs but
also in monkeys. In some instances they were found where a histologic
examination of the costochondral junctions showed nothing abnormal.
"Profound changes were recorded where the scorbutic changes during life
were so slight as to be almost unrecognizable," and, they continue, "the
mildest degree of scurvy which could just be discovered at the
postmortem examination produced well-defined changes in the structure of
the teeth." If this work is confirmed, we must consider the teeth as one
of the first tissues of the body to be affected by scurvy. The authors
quite rightly raise the question whether the teeth of young children may
not likewise be injured by a deficiency of antiscorbutic vitamine,
whether this may not play a rôle in the dental caries so prevalent
among civilized communities. It is evident, they state, that such
transient conditions of infantile scurvy as have been described by Hess
as "subacute" or "latent" scurvy, may occur more often than is usually
suspected, and may reasonably be expected to influence dentition. It
seems quite possible that the caries of the permanent teeth is due not
only to infantile rickets but also to infantile scurvy.
Besides the typical histologic changes in the bones there are
alterations in _other organs_ which require mention. All investigators
have found a degeneration of the muscles, showing a loss of their
striations, swelling of the fibres, and the presence of
irregularly-distributed vacuoles and granules. The interstitial tissue
frequently is permeated with edema, as we should expect from gross
appearances. Holst and Froelich have reported a fatty degeneration of
the heart muscle, as well as of the epithelium of the mucous membrane of
the glands of the stomach and of the intestine. Hart and Lessing, in
their protocols of necropsies on monkeys, describe an interesting lesion
associated with the degenerated muscle fibres--a collection of granules
staining deep blue with hæmatoxylin and dissolving on the addition of
acid. These granules, interpreted as being composed of calcium, were
found in the muscles of the limbs, of the tongue, and in the heart. It
is reasonable to attribute their formation to an absorption of bone
throughout the body. Similar calcium deposits were seen frequently in
the adrenal glands, in their cortex, or at the border of the cortex and
medulla. This lesion gains special interest in view of the calcium
deposits described so frequently in connection with mercurial poisoning,
more particularly as the symptoms of scurvy and of this toxic condition
have marked clinical resemblances.
There has been but little histologic investigation of the _nerves_ in
experimental scurvy. In fact, the only systematic study of the kind is
that of Holst and Froelich, whose attention was drawn to this field in
an attempt to solve the relationship between scurvy and ship beriberi.
These writers found a true Wallerian polyneuritis in only two pigs, one
of which had been fed on wheat bread made with yeast, and the other on
decorticated barley. In many instances, however, there was extensive
degeneration of the axis cylinders without degeneration of the sheaths.
They do not, however, attribute great importance to these changes, as
the same lesions were found in the nerves of animals fed on cabbage and
fresh potatoes. In view of the confusing reports on the nerves of birds
in experiments on polyneuritis, one cannot be too careful in drawing
conclusions from histologic studies of this kind.
In the study by Jackson and Moore on experimental scurvy in guinea-pigs,
the histology of _the blood-vessels_ is carefully considered. "Marked
thinning of the wall" was found and depicted; "the wall as a whole had
partially melted away, leaving few traces." These parts of the wall
contained many small round bodies resembling cocci, which were stained a
deep blue by the Wright and the Giemsa methods. These bodies were
present also in the lumen of the vessel and in the inner layers of the
more normal portions of the wall. In addition to such changes in the
veins, "lesions having the shape, location, and characteristics of
infarcts, were found in the ends of the diaphyses of the long bones." As
a result of this pathologic picture the authors are of the opinion that
they may have been dealing with a mild infection. This is quite
possible, as scurvy tends to render the tissues less resistant to the
entrance of bacteria. We believe, however, that even if such were the
case, the phenomenon must be regarded merely as secondary in its
relation to the pathogenesis of scurvy.
Following the study on the pathology of experimental scurvy, Jackson and
Moore undertook to determine primarily whether the small stained bodies
seen in the sections of the scurvy lesions were bacteria. This
investigation has been cited frequently as presenting cogent evidence in
favor of the _infectious nature of scurvy_, so that it will be necessary
to consider it fully; the general question of whether scurvy is a
bacterial infection is discussed under the consideration of etiology.
As is well known, Morpurgo, a generation ago, claimed to have produced
rhachitic lesions in young rats by means of artificial infection with a
gram-positive diplococcus. Pappenheimer brought about similar lesions in
rats by the injection of a suspension of bone marrow from a rhachitic
animal. Koch injected a streptococcus longus intravenously into young
dogs, occasioning gross bony changes of the epiphyses and costochondral
junctions, and microscopic changes resembling scurvy--an irregular line
of ossification and "a framework" marrow, which, however, showed regions
of osteoid. Jackson and Moody were able to isolate from the crushed
tissue of their guinea-pigs "a diplococcus of low virulence with a
tendency to form chains and produce green (color) on blood agar." Pure
strains of these organisms inoculated into the circulation of
guinea-pigs and rabbits, living under ordinary conditions (a mixed diet
consisting of green vegetables, hay and oats), gave rise in most
instances to hemorrhagic and other lesions in the bones, joints,
muscles, lymph-glands or gums. Hemorrhages were found beneath the
periosteum in the region of the lower incisor teeth and the acetabulum
and ribs. These results are far from constituting evidence in favor of
the microbic origin of scurvy. They show merely that the tissues of
scorbutic animals frequently harbor bacteria, and that injections of
these bacteria will bring about hemorrhages which may be subperiosteal
in character. They are open to the specific criticism that scurvy was
produced readily in the rabbit, an animal which otherwise does not
develop scurvy, and, furthermore, they differ from feeding experiments
in inciting scurvy notwithstanding the fact that the animals were
receiving an antiscorbutic diet (green vegetables). Cultures of the
hearts' blood of the affected animals were sterile in every instance; a
result obtained likewise by Holst and Froelich.
Further studies of this kind should be carried out and should include
cultures of the blood and tissues of guinea-pigs in the various stages
of scurvy, especially the early stage. In addition, a histologic study
should be made of the bones of animals injected with bacteria
(preferably streptococci), in order to ascertain whether notwithstanding
an unrestricted diet, typical lesions can be produced by this means.
For further details of the pathology of scurvy, the reader is referred
to the chapter on human pathology.
=Symptoms.=--Let us consider the symptomatology of guinea-pig scurvy. In
the course of an observation of many hundreds of animals we have been
struck by the striking uniformity of the signs and symptoms. The animals
made use of were almost invariably of moderate size, weighing from 200
to 300 grams. Where heavier pigs were employed the disease progressed
less rapidly, but the signs were the same; they were, however, more
difficult to elicit, owing to the subcutaneous fat. Most of the animals
were on a diet of hay, oats and water _ad libitum_, but there was no
variation in symptoms where fat and fat-soluble vitamine were supplied
by an addition of egg yolk or of cod liver oil, or where egg albumen was
fed to render the protein adequate, or where the inorganic salts were
supplemented by additions of sodium or calcium chloride.
There is a variability in the sign which signalizes the onset of the
disorder--sometimes it consists of a flattening of the weight curve, at
others of an inordinate excitability of the animal, or frequently of a
tender joint, generally a wrist. The joints almost invariably become
tender early in the disease, causing the animal to wince and cry when it
is examined. Accompanying this tenderness there is often slight swelling
due to edema, or perhaps some hemorrhage, which alters the sharp,
clean-cut contour of the joint. This edema may extend upward along the
tendon sheaths. Soon the animal becomes lethargic rather than nervously
active, and may look ill, as manifested by a roughness of its coat and
its unnatural posture. Frequently it sits on three legs with the tender
hind leg drawn upward and outward so as to escape pressure--a posture
termed by Chick, Hume and Skelton (1918, 2) "_the scurvy position_," and
indicative of hemorrhage into the joints or muscles. At times it lies
curled up, with the side of its face resting on the floor, as if to
support its painful or sensitive jaw; this they have termed the
"_face-ache position_." The two diagnostic signs, however, are the
hemorrhages about the joints and the loosening of the teeth. The
diagnosis frequently can be established by the twelfth to the fourteenth
day; the earliest diagnosis was made on the eighth day. Hemorrhages
appear somewhat later than tenderness, and are situated at the joints,
most frequently at the knee, which may be markedly swollen and show a
bluish or reddish discoloration, extending upward or downward for some
distance. Other joints are often involved, frequently the wrist, the
ankle or the shoulder. In other cases hemorrhages into the muscles are
noted, especially of the leg or of the thigh, and later, especially
toward the end, hemorrhages from the bowel. Fractures or separations of
the epiphyses may be found on examination or may be occasioned by the
physical examination. A frequent site of this lesion is at the wrist or
at the knee, involving the head of the tibia or the lower end of the
femur. These fractures knit rapidly when an antiscorbutic is given, but
result at times in deformity.
_Loosening of the teeth_ is another typical sign. It is, however, one
which does not appear early and is somewhat difficult to elicit. The
molar teeth are generally involved, especially those of the upper jaw,
which may be so completely separated from their alveolar sockets that
they can readily be removed by forceps. It is, however, impossible to
examine the molar teeth satisfactorily during life. Far less frequently
an incisor tooth becomes loosened; more often it loses its glistening
appearance and looks dull and yellowish. Occasionally an incisor tooth
fractures. The gums are rarely altered sufficiently to aid diagnosis;
not infrequently they are congested or bluish, rarely hemorrhagic, and
never ulcerous or spongy. This is the chief difference between the
symptomatology of scurvy in the guinea-pig and in man, and probably is
the result of lesser susceptibility of the former to infection by
pyogenic bacteria. In general, however, the disorder in the guinea-pig
bears a closer analogy to infantile than to adult scurvy; due to the
fact, possibly, that young pigs are generally used for the experiments.
A sign of great interest, although not of diagnostic importance, is the
_"beading" of the ribs_ noted by many observers, and emphasized by
Jackson and Moore. It has been described also in monkeys by Hart and
Lessing. This is an enlargement or swelling of the costochondral
junctions of the ribs, especially of the lower true ribs. It corresponds
clinically to the "beading" and the "rosary" so characteristic of
infantile rickets and mistakenly termed the "rhachitic rosary." As
pointed out, in discussing the symptomatology and pathology of human
scurvy, this sign must be regarded as truly scorbutic in animals as well
as in infants. The "rosary" is difficult to palpate in pigs which have
considerable subcutaneous tissue; in thin animals, however, its course
can be followed, the gradual development and subsequent disappearance.
In this connection the enlargement of the epiphyses must be mentioned,
another sign supposed to be characteristic of rickets in infants. Marked
swelling of the wrists is frequently encountered in guinea-pigs
suffering from scurvy--a bony enlargement involving the lower epiphyses
of the ulna and of the radius. This is met with far more commonly in
chronic scurvy than in the usual acute case. Where the disorder has
existed for a long period, these bony knobs may persist indefinitely,
constituting the sole residual sign of a former scorbutic condition.
The relation of _loss of weight_ to the development of the scurvy
requires consideration. In experiments carried out on rats to test the
diets in respect to the water-soluble and the fat-soluble vitamines, the
weight curve is used as the main criterion to judge whether the
foodstuff is adequate. In guinea-pigs we cannot employ the weight curve
as a criterion. Not infrequently an animal develops scurvy, and
nevertheless does not lose in weight, but even gains slowly and
steadily. This occurs when the appetite remains good, and the dietary is
complete except for antiscorbutic vitamine. The same holds true for
human scurvy, as we have noted in connection with the symptomatology. We
have attempted to make up for this defect by adding to the charts a
curve representing the clinical course (Fig. 10). Although this curve is
computed on an empirical basis, it gives a comparatively true picture of
the disease and is far more exact than attempting to portray the disease
by means of a weight curve.[38] Indeed, when we rely on the latter
method it is impossible frequently to illustrate graphically the
reaction of guinea-pigs to various influences. Another disadvantage of
the weight curve is that it is influenced by factors having no direct
relation to scurvy, especially infections of various types which retard
the gain.
[38] A maximum count of 35 was formulated, representing the highest
degree of clinical scurvy. This includes three grades of beading of the
ribs, four of tenderness of each knee and wrist joint, and four of
swelling of each of these joints. It is apparent from the clinical curve
(Fig. 10) that an animal may have developed a marked degree of scurvy
(20 points), and gained rather than have lost in weight.
[Illustration: FIG. 10.--Hay, oats, and water _ad libitum_ during period
I resulted in a lack of gain in weight, and in a development of scurvy.
During period II, 1.5 c.c. of orange juice were given daily, and as will
be seen there was a marked gain in weight and disappearance of the
scorbutic signs, although, as is generally the case, they continue to
develop for a short while after an antiscorbutic is given. When the
orange juice was discontinued in the third period, the weight once more
fell and the scurvy redeveloped. The broken line represents the course
of the scurvy, and is a composite formed on the basis of the aggregate
of the scorbutic signs. Each square represents a 2-day interval.]
Guinea-pigs generally die of scurvy after having lost about one-third of
their body weight; occasionally the loss is greater, reaching almost 50
per cent. This loss is due partly to the scorbutic condition, but to a
greater extent to starvation occasioned by a marked lack of appetite. In
this connection it may be noted that guinea-pigs frequently lose for a
few days following the addition of an antiscorbutic to the dietary (Fig.
11). This reaction is evident from a perusal of the weight charts of
other investigators, and occurs likewise in human scurvy. This loss is
accompanied, as Gerstenberger has pointed out, by diuresis, which may be
so marked that it is evident to the casual observation of those caring
for the animals.
[Illustration: FIG. 11.--These guinea-pigs developed scurvy in spite of
receiving a large quantity of the water in which young carrots had been
cooked for only 20 minutes. It will be noted, however, that although the
pigs developed scurvy they did not lose weight, as is usually the case.
After they had developed definite scurvy they were given in addition the
equivalent of 80 c.c. of a dried milk prepared by being heated to about
116° C. for a few seconds. The addition of this milk to the diet cured
the scurvy, showing that it had largely retained its antiscorbutic
vitamine.]
Exophthalmos may be mentioned again in this connection as a very rare
sign of guinea-pig scurvy. Hæmaturia also occurs at times; it is not
known how frequently it is present, whether it is an early manifestation
in the guinea-pig as in the infant, or whether the source of the blood
is the kidney or the bladder.
The superficial lymphatic glands are frequently palpable in scurvy,
especially those in the inguinal region. This sign is emphasized by some
pathologists. It has seemed to us attributable less to the nutritional
condition than to the infections which so frequently complicate the
disorder.
According to Jackson and Moore a rise of temperature does not accompany
scurvy in the guinea-pig. As the result of an examination of nine
guinea-pigs they conclude that "experimental scurvy is a non-febrile
disease in the majority of affected animals." Nor did they find a
leucocytosis, the average leucocyte count of eight scorbutic pigs being
about 8000.
As the data are meagre, a consideration of the chemical alterations
associated with the scurvy of guinea-pigs and monkeys will be taken up
in conjunction with the metabolism of human scurvy. The therapy of
animal scurvy will also be deferred (chapter VI), as the reaction to
dietetic measures is practically the same in man and in animals. In
concluding this chapter we would call attention to the following
interesting statement contained in the recent paper by Delf and Tozer:
"In other experiments, however, where a liberal supply of an
antiscorbutic was given and where the fat-soluble A growth factor was
known to be deficient, the resulting histological changes in the
rib-junctions of the animals examined were found to resemble closely
those of 'Definite' or of 'Definite Chronic' scurvy. In these test cases
the antiscorbutic chosen was, we believed, deficient in the fat-soluble
A growth factor (for example, orange juice). This fact is mentioned
because in the case of an animal not receiving an adequate supply of
fat-soluble A the resulting changes in the junctions are not dissimilar
from, and are likely to be confused with, those caused by scurvy alone."
If this observation is confirmed, it emphasizes the necessity in
nutritional experiments, of constructing a dietary which is complete in
every respect except the one under investigation; it also suggests the
development of new pathologic entities in relation to other nutritional
disorders resulting from a lack of the accessory food factors.