Part 19

Our records have been analyzed from the standpoint of diagnosis and the most probable cause. The first will be taken up in discussing each of the orders. The probable causes are divided into food, bacteria, animal parasites, physical objects and undecided, in other words a classification based upon the most prominent or definite evidences as seen at postmortem combined when possible with antemortem observations. When findings were inconclusive or contradictory, cases were called undecided, naturally a very large group. Fermentative processes in the presence of obviously undigestible material, are classified with food as a cause. When evidences of septicemia existed in absence of the other factors, it is held that bacteria were responsible. Cases were grouped under animal parasites when these were the most definite findings. Physical objects are relatively unimportant and self-explanatory. To the etiological chart there are appended columns intended to show the percentage or case incidence of the disease of the grosser subdivisions of the gastrointestinal tract which indicate in a general manner what part of the tube in the various orders is most susceptible to disease. While of course conclusions must be drawn with great caution, there can be little doubt, for example, that carnivores and marsupials have more gastric disease than any other order, and that the high place for the colon is held by the gallinaceous birds. This charting was suggested by the work of Dr. Raymond Pearl upon statistics, wherein he takes as a basis of classification the part of the body which succumbs to disease- producing organisms or from which a disease starts. It cannot be stated that there is a clear cut relationship between enteritis and the expectancy of life.

MAMMALIA.

The PRIMATES as an order have their share of inflammations of the gastrointestinal tract and present points of interest. Acute digestive disorders succeeded by acute dilatation of the stomach, or in less fermentative cases by acute catarrh of the intestine, are not at all uncommon. The reason for this is not discovered by reviewing the diet and manner of feeding. The buccal pouches, distensible esophagus, the freely movable stomach, and relatively elastic gastric wall would seem to permit of very considerable dilatation to accommodate the large quantities which the monkey sometimes crams into himself. Nine fairly acceptable records of gastric overfilling exist and two of them seem to have been followed by tympanites sufficient to embarrass respiration, in one case there occurring an acute cardiac dilatation with myocardial degeneration. The animals give no symptoms of this condition and in the last case cited the beast, while old, ate well and was not distended the evening before death.

When acute gastritis exists (twenty cases) the animal seems uneasy but does not vomit. On one occasion I was called to see a monkey which was retching and seemed in pain. Lime juice was offered and taken, followed by gentian and cardamon, which seemed to give some benefit. Somewhat later this was repeated in another case, but observations where this might be useful are rare.

The pathology of gastric conditions offers little to contrast with that of man. The enormous distensibility of the fundal pouch often suggests to the observer the rumen of ungulates. Acute gastritis of one kind or another and acute catarrhal enteritis are the most common lesions noted in the Primates. Involvement of the intestine or colon need not carry with it an increase of signs of illness, although at times one will see an evidently sick animal with diarrhœa. Anatomically the lesions are commonly restricted to the stretches of gut _above_ the ileum, it being rather rare that this division or the colon is affected. Pathologically the lesions are catarrhal with definite involvement of the follicles in about one-third of the cases. In this order toxic and pseudomembranous forms are quite rare and ulcerative lesions uncommon. Colonic disease as a sequel to inflammation higher up is sometimes seen in the follicular varieties, but takes a minor place compared to amœbic dysentery of which we have had several cases; this will be discussed under a separate heading. Degenerative disease of the skeleton is almost always accompanied by a low grade of enteritis but not necessarily gastritis or colitis. The pallor of the mucosa, while at times striking, may be relieved by follicular spots and petechia or pigmentation. Often, however, animals suffering from osteomalacia and rickets come to their end by an acute inflammation of the gut tract.

The bacteriology at our disposal allows no conclusions. Aside from a case probably due to Ps. fluorescens and one with colon bacillus abscesses in the liver, no reliable data are at hand.

Reference to Table 11 reveals the fact that among orders with sufficient autopsies to permit percentages, the alimentary tract in monkeys is in the group of low figures, that the intestinal section is relatively more often affected, and that the colon is more often diseased than in other mammalian orders, and is exceeded only by the gallinaceous birds.

The LEMURES, of which we have eighty-six autopsies, do not differ much in anatomy from the Primates, however greatly they disagree in habits and outward appearance; their diet is the same. Clinically the slothful behavior of a normal lemur probably obscures symptoms and signs of illness, for our antemortem notes with the exception of a few observations of loose stools, fail to offer a lead as to diagnosis. This order has a large incidence (twenty-three cases) of gastroenteric conditions as shown in Table 11, but some explanation of the figures is deserved. In the first place, only one case of acute gastritis occurred, and this was apparently a part of a general infection, and if induced at all by food this was only secondary. Indeed as one reviews the records it does not seem that the lemurs are easily disturbed in their gastric digestion. Acute and subacute inflammations from bacterial action seem definitely more prominent since they take the catarrhal, follicular and deep submucous form and are frequently associated with generalized infectious processes. One amœbic case was observed and there was another in which a heavy cestode and nematode infestation seemed to have paved the way for bacteria.

CARNIVORA.

The food of this order is received into the fundal part of the stomach, the distensible but normally capacious left and superior two-thirds of the organ. The general shape of the viscus, that of a gourd, permits a fairly sharp separation of the fundal and pyloric sections, so definite indeed that the pathology of the two parts was studied. The intestines vary in length, but in the land carnivores are relatively short, narrow in lumen and rich in wall. A cecum, or at least a blind end of the large gut made by the insertion of the small intestine above the tip of the colon, is suggested in all families, although, as in the bears, it may be quite insignificant or rudimentary. Theoretically no stasis should occur at this point. The colon is short in all carnivores and, like the small gut, with a heavy wall. The comparative simplicity of the carnivorous gut tract, the ability of many of these animals to disgorge, the suggestion of high resistance of the upper end of the tract to infection and the ease with which diarrhœa can clear out the tube, would seem to warrant the expectation that inflammation would not be serious. Such, however, is not the fact for, on the contrary, they have shown a higher incidence than any other order for which we have adequate comparison. Anatomically considered their stomach occupies the second place in vulnerability, next to the marsupials, and their intestines the highest place; this indicates of course that combined gastric and intestinal disease has often occurred. Involvement of the colon occupies the second place, in ordinate susceptibility, being exceeded only by the monkeys, due to heavy parasitic infestation, but would occupy the first place were the eleven amœbic dysenteries in monkeys subtracted from their total, a subtraction which might be allowed since it represented an epizoötic outbreak.

Etiologically considered, it would seem as if the influence of incorrect feeding were of little importance, and from one standpoint this is probably the case. Acute fermentative or irritative processes are not common at all, while more inflammatory pictures, catarrhal, erosive or ulcerative, are the rule. There is another phase to the term incorrect food, that is incorrect in its cleanness. During 1912–15 there was an increasing mortality among the cats and dogs fed upon horse meat, mutton and fowl heads. Early in 1916 the butcher shop was reconstructed and thoroughly cleaned and covered galvanized pans supplied in which to transport the food; these pans were scrubbed and scalded after use. Since that time, infections inflammations of the stomach and intestines have shown an ever increasing downward incidence, which result, there having been no material changes in other directions, I do not hesitate to ascribe to the improvement of butchering and dispensing engineered by Dr. W. B. Cadwalader.

Helminths seem to be of importance in this order both by reason of the percentage of autopsies in which they presented the most probable or at least most suggestive cause and because uncinaria and strongylus have been seen attached to the wall and a large bulk of known irritative cestodes have occupied the lumen. Physical objects, stones, bones, wire, may cause irritation enough to activate bacterial action or may actually penetrate the wall; the latter action is well known. In so far as practical application of this is concerned, it teaches to feed whole, unsplintered or ground bone.

The distribution and character of pathological lesions according to the region of the stomach is what might be expected from the shape and physiology of its parts. True inflammatory processes are best, and in some cases only seen in the pyloric half of the viscus, while the changes in those few cases believed to be fermentative or irritative in nature were largely confined to the fundus. Dilatation of the latter part may be understood because there the muscular coats are about equal to the mucous in thickness and one-half the width of those at the pylorus, but why inflammatory processes should not be so developed in the fundus is not clear unless the greater availability of mucus protects the secreting wall. Not only does acute inflammation reach its most definite form in the second part of the stomach, but the irregular pigmentation, mammillated overgrowth and atrophy or ulceration of chronic disease are likewise best seen in this part.

Acute enteritis, of all varieties, is seen more beautifully in carnivores than in any other order of mammals, and nowhere can it be studied better. Its gross appearance is that of the text-book and its minute character even more instructive. I have used a slide of acute catarrhal enteritis in a lion for the illustration of this lesion for the _Text-book of Pathology_ by Doctor Stengel and myself. However, as is known to all who have paid any attention to enteritis, the postmortem findings are usually much less definite than clinical observations would warrant one to expect. The Carnivora not uncommonly show intestinal congestion, mucous membrane swelling without edema or opacity, congestion of the spleen, cloudy swelling of the liver and kidneys and perhaps mesenteric lymph node edema. This picture we have viewed as a toxic affair of some sort or a bacterial infection not yet far enough advanced to produce catarrhal or ulcerative enteritis and septicemia. In such cases the carnivorous intestinal mucosa offers instruction. The epithelium is vacuolated or fringed on the free edge or may be missing altogether. In the depths mucus formation is very active, and where it is going on, round cells seem attracted, collecting in groups in the villus or in the subjacent submucosa. Perivascular round cell increase may be noted. Plasma cells and granular eosinophiles are common, but I cannot state how important the latter are in the general picture because of the frequency of parasites in carnivores. The central vessel of the villus and the arterioles of the submucosa are injected. Lymph follicles may or may not be enlarged, but if so usually fail to show a germ centre.

Colitis alone is not common in this order, but as an extension process or involvement at the same time as the upper levels it occurs occasionally. The only fact I wish to record and one which I would emphasize because of having seen it recently in a human case of chronic colitis, and since it does not appear important to systematic writers, is superficial blood supply. The capillary network of the colonic villi, while rich, is in the form of a fine plexus just under the epithelium. In the cases studied these vessels become quite distinct and possess much more definite walls, often bordered by mononuclears, while connective tissue is more evident at the bases of the villi and deeper. This may help in deciding the existence of a colitis.

Bacteriologically the most instructive experience to report is the discovery that a small outbreak of enteritis among small Carnivora, chiefly cats, fed upon fowl heads was due to Bact. paracoli, or at least this organism was found in the intestinal mucosa, spleen, and heart’s blood of three cases. The type of enteritis was hemorrhagic and follicular. There was also a case of septicemia apparently emanating from enteritis due to Bact. suipestifer in a lion (_Felis leo_). These facts bring strongly to attention the modern teaching that meat poisonings of the Gärtner type are to be considered as infectious and not of the so-called ptomaine group.

PINNIPEDIA, while related closely to the Carnivora, are grouped in a suborder in our classification and because of their restricted diet are treated here in a separate paragraph. The tract is peculiar in the strong tubular stomach sharply bent upon itself, the great length of the small gut (upwards of a hundred feet in some genera), and the practical absence of a cecum. Pathologically speaking, the most striking lesion of these animals is ulcerative gastritis, a process usually most marked along the posterior-superior surface, but not confined thereto. Upon inspection the gastric mucosa, normally supplied with low regular rugæ, is much distorted by swellings upon the top of which are irregular ragged ulcers with rounded elevated but not frayed margins. The density of the edges indicates much infiltration of the deep mucosa and submucosa; this can be confirmed by microscopical examination. One attempt to study this gastritis bacteriologically was fruitless. Sections of one case showed streptothrix-like masses while in another case bacterial colonies and yeast-like bodies were found in adjacent lymph nodes. The genesis of this condition might lie in injury by fish fins or by foreign bodies, of which large numbers are found at times (a pint and a half of stones, marbles, and sticks were found in one stomach). Gastritis has been the starting point of septicemia on two occasions, and three times an acute exacerbation or new implantation of infection occurred, with extension into the intestine. It is interesting that all the deaths of Pinnipedia with gastroenteric conditions occurred in the winter months.

INSECTIVORA are represented by two common European Hedgehogs. In one there were three shallow but shelving ulcers in the stomach which had bled sufficiently to weaken the animal; free blood was found in the intestine. The other specimen was diagnosed at postmortem as having catarrhal enteritis involving nearly the whole small gut, but histological section did not confirm this.

As one descends the zoological scale the first gastrointestinal tract prepared for the nutritional care of bulky food is to be found in the RODENTIA. This order presents a great variety of shapes and arrangements of the stomach, but the outstanding feature, with very few exceptions (cf. spermophiles), is the development of the cardiac and fundal divisions ostensibly for the reception of a large bulk of coarse food to be digested at leisure. Some genera like the hamster (_Cricetus_) have a stomach closely resembling the ruminants, while that of the spermophile suggests the equine stomach. The pyloric end, variable in many ways, greatly resembles the abomasum. So too the duodenum is large, loose and distensible while the copious small gut ends in a very large cecum, shaped at times in a manner which has led to the term “colonic stomach.” The colon is variable and not always supplied with longitudinal bands and sacculations.

In regard to incidence of gastrointestinal disease, rodents occupy a middle position in the table. The stomach seems a vulnerable section of the tract. Dilatation of the left hand section is common, due, to all appearances, to fermentative processes which have as a result the softening of the mucosa so that even immediately after death it will separate almost entirely. In these cases the pyloric part need not participate but may remain flat, smooth, soft and pink. This condition is slightly more common in the compound than in the simple stomachs. In some of this order, especially rats and cavies, there is a fermentative gastroenteritis expressed by injection and edema of the pylorus and duodenum, and much frothy mucus. It was at first thought that some relation might exist between this condition and the absence of the gall- bladder, but it occurs in varieties possessing this structure. The reaction of the intestine to irritation in this order is peculiar in two ways, the occurrence of mucus and the activity of the lymphatics. In all the inflammations from and including the stomach to the cecum, mucus is conspicuous. At times it is thin or loose and mixed with contents, while at others it forms a relatively close covering for the mucosa almost like a false membrane. Rodentia are peculiar in the promptness and clearness with which the follicles of the intestinal wall and mesentery enlarge in inflammation. They appear as pale, well outlined or diffuse opacities in the wall or as distinct plaques prominent on the surface.

The PROBOSCIDEA are represented by one Elephant (_Elephas indicus_), in which a mild catarrhal change was seen in the middle stretches of the small intestine. This was of little importance as a cause of death, there being several other diagnoses, and was probably a terminal affair.

HYRACES, of which we have a total of seven examples, present two mild involvements of the intestine but none of the stomach. It would appear from the records that the intestinal condition had little to do with the death of the animals, and unfortunately no microscopic slides were made. Because of the curious formation of the large gut, notes of both ceca were made in one case, and can be condensed as follows: “The upper or anterior cecum presented a shaggy pearl gray mucous covering, closely attached to the mucosa. This cavity and the posterior ceca were packed with dry crumbling feces. Small thin-walled cysts were seen in the tips of the lower ceca. Duodenum was congested and mucosa swollen. Stomach contained dry, poorly digested food. No parasites were found.”

The EDENTATA are represented by an Armadillo (_Tatu novemcinctus_) and an Anteater (_Myrmecophaga tridactyla_.) The former had a prolapse of the rectum accompanied by colitis but it is impossible to decide the priority of the two conditions since the former is known to have existed long enough to have permitted the latter to develop. The Anteater had a distinct mucocatarrhal enteritis in which bacteria played a part since involvement of the liver, spleen, kidney and lymph nodes also existed. The beast was in good condition upon arrival, but did not become accustomed to the proffered diet, and was distinctly anemic at death.

The UNGULATA, so-called for their hoofed and horned character, are also associated anatomically by the construction of their gastrointestinal tract. However, the order of the list as given on page 44 does not represent their historical development nor does it accord with anatomical arrangement of the tube under discussion. The last three families of Artiodactyla are perhaps the simplest in the construction of this tube, or at least take an equal place with the Perissodactyla, while the remaining families of the former suborder have a complex tract of generally similar architecture. This whole order has, however, an alimentary tract anatomically suited for the consumption of bulky vegetable stuffs and shows an attempt at adjustment between the food, the methods of mastication, the area of digestive surface, and the bulk necessary for nutrition. The number of factors opened up by the many variations between this complex tract and that of the carnivorous simple tract is so great that I shall attempt only to contrast the anatomy and pathology of the simpler ungulate tracts and the complex ruminant apparatus.

The simpler gastrointestinal tract is possessed by the Perissodactyla, and by the following families of Artiodactyla, the Phachocœridæ, Suidæ and Tayassuidæ. This consists of a stomach with a single cavity (some Peccaries have partitions but no true septa with strict histological differences) divided into esophageal, cardiac, fundal and pyloric areas, dependent upon the nature of the lining epithelia and the absence or presence of glands, as well as the nature of the tubules. The duodenal section is ample and may be sacculated while the intestines are small in calibre and rather sturdy in wall. The cecum is relatively very large, well supplied by longitudinal bands and sacculations; the colon is relatively short but quite capacious and sacculated.

The ruminants and other remaining members of the Artiodactyla have a compound stomach suited to the separation of coarse and fluid foods and the retention of water, and so arranged that boluses of different densities are distributed as needed. These divisions are histologically as well as grossly different. The first three, comparable to the esophageal section of the simpler stomach, are reservoirs or channels, while the fourth or true digestive section, is divided into areas corresponding to fundus and pylorus, possessing the appropriate type of gland. The duodenum in this group is narrow, as is the rest of the small gut, and has delicate walls. The cecum proper is short and of variable width, but never as great as in the group first discussed, while the colon, an intricately wound tube, is narrow and very long. Certain of the first group (Peccaries) have a colon of this type, but it is not so complicated as in true ruminants.

These complications seem designed to permit of a long retention of coarse food of low nutritive value per bulk for a time sufficient for full digestion; reverse adaptation of large size of stomach and colon may be explained on the same basis. Let us now examine these two groups to discover their pathological reactions and the nature of the lesions.