Chapter X: Section VII: The Alimentary Tract. Part 1.—pharynx, Esophagus, Stomach and Intestines (2)

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.

TABLE 12. _Showing the Percentage Incidence of Various Forms of Inflammation in the Alimentary Tract of Ungulata._ ══════════════════════════════════╤═════════════════╤═════════════════ Lesion │ Group A │ Group B │ Perissodactyla │ Ruminants and │ and Swine, Wart │ Relatives Per │ Hogs, Peccaries │ cent. │ Per cent. │ ──────────────────────────────────┼─────────────────┼───────────────── Acute fermentative gastritis │ 18.│ 2.1 All other forms of gastritis │ 16.3│ 5. Acute toxic or fermentative │ 1.6│ 2.3 enteritis │ │ All other forms of acute enteritis│ 1.6│ 8.4 Chronic enteritis │ 0.│ 1.9 Colitis and typhlitis │ 0.│ 3.1 ──────────────────────────────────┴─────────────────┴─────────────────

Ungulates as a class stand in a position equivalent to the Primates in the incidence of gastrointestinal diseases. They show a conspicuous percentage of cases apparently due to incorrect food and, coupled with this, a high percentage of gastric involvement, being exceeded in this respect by the marsupials only (there is an adequate reason for this—see below). Cases ascribed to bacterial or parasitic agents are not numerous. Analysis of the records of the two groups discussed above brings out some interesting facts. Consultation of Table 12 shows percentage comparisons, based on the number of autopsies, of lesions in the various sections of the tract. Group A, that with the simple stomach and the short capacious colon, is represented by forty-four specimens, while Group B embraces 321 animals. Perhaps the use of these two widely differing figures for comparison is open to some objection which might be final and decisive were not the figures so definite. At a glance one can see that Group A has involvement more marked high in the tract while Group B has more disease in the intestine and colon. Certainly gastritis is more common (five times) in the A than in the B group, while enteritis is more common in B (over three times). No case of chronic enteritis or of involvement of the colon is recorded in animals with a simple stomach and a wide hind-gut. This may be read either in terms of vulnerability of the stomach or in the degree of resistance of the respective groups.

Consideration of the local factors of the stomach brings to light at once the fact that incorrect food entering the simple stomach could attack the softer, less resistant glandular section of the fundal and pyloric areas whereas the rumen and psalter of the compound organ, with their stratified epithelium devoid of glands, act as barriers or as places where detoxication of irritants might take place. In both groups bulky food is packed to the left, the esophageal and cardiac section in the simple form, the rumen in the compound. Soft or liquid food may pass into the psalter and abomasum of the ruminant stomach almost directly since it has not the force or bulk to push aside the valve-like fold of wall at the junction of esophagus, rumen and reticulum. For this reason, if for no other, the character of soft food supplied to this order must be unexceptionable.

It has not been possible to follow out the layering of diets as Scheunert did when showing the course of various foods before they are mixed at the beginning of the pyloric compartments. We have seen two cases in ruminants which seem to indicate that soft food had passed into the right side cavities of the stomach, there to cause irritation, while the rumen remained quite normal. It seems, however, accepted by veterinarians that excessive soft food may be followed by trouble in the digestive stomachs, while excessive dry food may cause distention of the left hand sections. So far as I know, the relative incidence of gastric disorders in the above outlined groups has not been pointed out before.

The pathological types of gastroenteritis do not present many unusual features. Simple injection of vessels during digestion seems more evident in this than any other order, while mucus production seems less marked. The mucosa of the reservoir portions may, in simple overfilling and fermentative distention (gastric tympanites), be quite normal or dull red; when active fermentation has occurred it may be digested and peel off. More or less true inflammation as seen in the digestive stomachs is definitely better expressed in the compound ruminant organ than in the simple equine variety where congestion and edematous swelling with hemorrhage form the usual picture. True catarrhal changes both gross and minute, are often well seen and ulcerative lesions are not uncommon; ulcers are unusual in the simple stomach. These statements hold good also for the small intestine. Enteritis affects the duodenum and jejunum more in the Perissodactyla and swine than in the ruminants. Ungulata do not react with hyperplasia of the mural lymphatics as do many other orders, but the swelling of the mesenteric nodes is often noteworthy. As might be expected this is more definite with catarrhal changes and therefore best seen in the ruminants. In the colon, however, the solitary follicles are often quite prominent in simple inflammation. Histologically the greatest changes seen in this order are superficial degenerations with mononuclear increase in the deep submucosa, mostly arranged in perivascular fashion. The villi do not contain the large number of cells seen in the Carnivora.

MARSUPIALIA.

Consultation of the figures for this order in Table 11 arrests attention at once because of the peculiar percentages found under the detailed factors. Thus food is of no moment as a disturber of the alimentary tract, while bacteria and parasites are high in importance. The gastric segment is more often attacked than any other portion and slightly more often than in the nearest order, Carnivora. These unusual figures deserve explanation, to which purpose it will be necessary to consider the anatomy of the organ and to discuss why bacteria and parasites stand so high in etiology.

Marsupials are divided into six families in our classification (see page 44) which in regard to their diet, range from largely carnivorous (the first two) through those choosing mixed insects, fruits and vegetables (the second two) to those eating vegetables and grain (the last two). The stomach of these animals does not vary exactly according to their diet, the first four, opossums, dasyures, bandicoots and wombats, possessing an organ closely similar in outline and construction and resembling the carnivorous variety, while the phalangers and kangaroos have a stomach entirely different from the first four although somewhat similar to one another. The first group has a round or irregularly elliptical organ with the esophagus and pylorus close together along the lesser curvature. The wombats have a bank of glands surrounded by a capsule, near the cardia. The stomach of the first four animals is divided into cardiac, fundal and pyloric parts by the construction of their mucosa, the first mentioned division being a high, rounded pouch, rumen-like, well to the left. The phalanger’s stomach is more elongated, the two openings well separated and a fissure is found in the right end of the lesser curvature which serves to separate the pyloric part from the rest. The Macropodidæ all have a stomach resembling the human colon in being elongated, with longitudinal bands gathering it into sacculations. There is a distinct esophageal section to the left with a blind sac suggesting an ungulate rumen, a long tubular fundal, and a sacculate pyloric division.

The small intestine of the order starts with the opossums as a stout muscular and mucous tube fitted for meat eating, but as one proceeds to study the families downward in the list this tube becomes more delicate and longer. In the first two families the cecum is rudimentary and the colon very short as in cats, but the length and capacity of these parts increase through the bandicoots and wombats until in the strict fruit, vegetable and grain eaters, phalangers and kangaroos, the cecum is long and capacious and the colon relatively long and roomy.

TABLE 13.
_Showing the Incidence of Gastroenteric Disease in the Two Forms of
Marsupial Intestinal Tracts._
═══════════════════════╤═══════════════════════╤═══════════════════════
│ Group A │ Group B
│Carnivorous Stomach and│Herbivorous Stomach and
│ Intestines 103 │Intestines 73 Specimens
│ Specimens Per cent. │ Per cent.
───────────────────────┼───────────────────────┼───────────────────────
Acute gastritis │ 9.6 │ 15.
│ Bacteria Verminous │ Bacteria Verminous
Chronic gastritis │ 0. 13.6 │ 5.4 0.
Acute enteritis │ 2.9 │ 1.5
Colitis incl. typhlitis│ 1.9 │ 4.3
───────────────────────┴───────────────────────┴───────────────────────

Table 13 contains an analysis of the forms of gastroenteritis as they were described in the two groups of tracts, that resembling the carnivorous, that similar to the herbivorous intestinal construction, and according to the factor believed to be responsible. In the first group gastritis of an acute nature occurred in 9.6 per cent. of the 103 specimens. They were chiefly catarrhal in character and seem for the most part secondary to verminous infestation; at least six of the ten cases were associated with parasites. The process microscopically is catarrhal and deeply infiltrative. Group B has a high incidence of gastritis and here the evidence of bacteria or toxins is quite plain. Several of the cases were in animals showing also Kangaroo disease of the jaw with pneumonia or septicemia; the gastric lesion of streptothricosis will be described under that heading. The character of gastritis without jaw disease is somewhat different from that with it. Pathologically the process is a congestive and superficially necrotizing affair, forming upon the tips of the folds, small gray erosions or flat shallow irregular ulcers, which upon histological study consist of loss of tissue of the mucosa and some deep congestion with round cell groups but no reaction deep in mucosa or submucosa. True catarrhal inflammation has occurred, but not like in the opossums.

Chronic gastritis in the simple stomachs is almost exclusively in opossums harboring _Physaloptera turgida_, a worm which fastens itself more or less firmly in the mucosa and probably, with the assistance of bacteria, causes sufficient irritation to produce a hypertrophic change in the deeper layers and a destruction of the glands where it holds and a distortion of those nearby. One is reminded that Fibiger found spiroptera to be responsible for adenocarcinoma in rats; no tumor formation has been found in these animals, although one opossum with such a stomach had an adenocarcinoma mammæ. Small hemorrhagic spots may occur in the deeper layers, possibly where the worms have bitten. The rugæ are irregular or interrupted by knobs and papillæ.

Group B, stomachs showing chronic change, were all kangaroos. The three cases resembled the infiltrating necrotizing lesions as discussed under ulcers (page 175). The process showed an infiltration of the subsurface tissues with a gray slough over the densest part. The mucosa as a whole was irregularly rugous and spotted with red gray areas.

Altogether one gets the impression that in the simpler stomach, reactive inflammation is most prominent, while in the colonoid stomach degeneration is greater than reaction.

Intestinal lesions in marsupials are not common and not peculiar except in that they carry out the pathological reaction as seen in the stomach. The carnivorous intestine shows frank catarrhal changes, the herbivorous presents congestions and superficial necroses. These two groups then follow the descriptions as already given for carnivores and ruminants.

The colon presented in the first group, simple catarrhal or follicular change. In the second division the lesions resembled those in the stomach; they were only once of the three instances associated with streptothricosis.

AVES.

The class Aves has been treated in the chart precisely as have the mammals, but it is not possible to make the accurate diagnoses or to separate groups of lesions according to anatomy as was done for the latter class. Upon the average there is more gastroenteritis among birds than mammals, but when looking for an explanation of this, it was unfortunately necessary to enter in the “undecided” column of Table 11 a very great number of cases. This column would be greater relatively were it not for the parasites in parrots and gallinaceous birds, the entries for which are high. Besides this fact and that the owl stands at the top, the pigeons at the bottom of the list numerically, no further general statements are allowable. There are several orders with high values among those of which insufficient autopsies are at hand to cast percentages.

The avian alimentary tract seems to have developed according to the character of food the different varieties of birds consume if one may judge by the construction of the bill, the gastric musculature and the intestinal wall. Zoological classification has only secondarily considered this point, it being made incidental to the habits and habitats of birds. For this reason the orders as outlined on pages 44–46, placed as they are in historical evolutionary position, represent with few exceptions groups which have differing diets and, by the same token, differing gastrointestinal tracts. Classifications based upon habits of life (Raptores, Cantores, Natores), prove likewise too broad or too heterogeneous, while systems making character of food the chief criterion though apparently correct in reasoning and helpful in certain orders, (Accipitres, Galli) are found to present copious exceptions; moreover we are imperfectly informed of the exact diet that many families require or resort to in absence of their preferred food. I shall therefore discuss the chief diseases and distributions according to our classification, preceding the discussion by a brief résumé of the anatomical peculiarities of the avian alimentary tube.

The first digestive burden falls upon the proventricle where the principal juices are secreted while the muscular stomach or gizzard assumes the duty of gastric mastication. The lateral muscular bellies of its heavy wall grind the food and mix well the gastric juices. Its mucosa probably supplies only lubricant. In birds whose food is hard, corn and the like, this grinder is supplied with a dry horny internal layer, while a thick, moist, soft, epithelial surface is sufficient for carnivorous birds. All kinds of gradations exist between these extremes. The mucosa of the proventricle is always soft, but quite deep to permit the placement of compound tubular glands.

The relation of size of these two parts is subject to many variations.[22] The proventricle is larger proportionately in meat eating, fish-eating and fruit eating birds, the gizzard having the greater size in granivora and insectivora. In certain birds the mucosa of the two is separated by a very soft thin zone, an important fact in Psittaci since at this place spiroptera seem to penetrate to the glandular layer of both organs.

The duodenum begins in practically all birds, from a spherical cavity at the pyloric end of the gizzard, to be accredited anatomically to both sections. It passes downward, forms a long loop enclosing the pancreas, its distal end lying under the liver and near the gall-bladder. Near its end it receives the major bile and pancreatic ducts; smaller ducts from the liver and pancreas may enter near the pylorus or elsewhere along the loop. The small intestine is usually simple in its coils, but in the birds that eat grain, grass and greens, may be long and complicated. So too the colon, usually a very short segment, may be increased in the just mentioned group while the ceca are only of any considerable length in herbivorous birds. The length of the ceca is, according to Owen, related to the availability of food and the need the bird may have for exhausting the nutritive value of it. In carnivorous birds as in similar mammals, the whole gut, but especially the hind-gut, is very short and the ceca small or absent. But so they are in picarian birds which are chiefly herbivorous, but may eat meat.

GASTRITIS.

The double-muscle stomach, that with the two lateral plates and tough epidermal internal coating, is seldom the seat of disease. An excess of greens in the diet sometimes seems to soften or macerate the lining, while an excess of pebbles may cause erosions. Upon severe irritation this internal layer assumes the appearance of tanned leather and may crack. The proventricle of such a gizzard seems rather resistant to disease, particularly one would say, to infective processes, for catarrhal or ulcerative inflammation is uncommon. The saccular stomach with uniform muscular walls continuous with those of the proventricle, such as is seen in raptatory birds and parrots, offers a somewhat different picture. The internal membranes of these organs are definitely softer, seeming to swell with great ease, and the glands themselves are smaller both at the fundus and outlet, a construction which may favor their closure by swelling from simple congestion and edema. Catarrhal and ulcerative processes are definitely more common in such organs than in the first type or true gizzard.

ENTERITIS.

Enteritis of all orders is most outspoken in the duodenal loop, but a determination of the lesion must be made with some care. All the signs of intestinal inflammation—congestion, swelling and opacity, excess mucus or mucopurulent covering—must be present to justify a gross diagnosis of enteritis and even when these exist one fails at times to confirm the finding by microscopical section. These changes may be simulated by digestive activity so that it is but reasonable to demand them all in a clear cut fashion before applying the term enteritis. However, it is well known that cases in both human and veterinary medicine giving a satisfactory clinical picture of this disease may fail to show to the naked eye and under magnification the changes expected.

In the human being, the carnivore and the ruminant, the ileum presents the most definite picture of enteritis. In the bird, the duodenum shows the prominent lesions, and with the exception of specific diseases like blackhead, is always involved when the smaller coil of small intestine is affected. This is true whether the enteritis be nonspecific or be associated with cholera of chickens, ducks or parrots.

The colon presents peculiar lesions in but few birds. Ulcerative and necrotizing processes have been encountered in three orders, Psittaci, Anseres and Herodiones, suggestively like the specific forms seen in the ceca. Microscopy and one unsuccessful culture failed to reveal a mould or protozoön. The condition appears as a gray white plaque in the cloacal wall or it may spread up to the colon and around the urethral orifices. At times it is superficial upon the mucosa and may be covered by a pseudomembrane.

The chief interest in the ceca centres about enterohepatitis either of heterakis and amœbic origin or that supposed to be due to coccidia or Bac. scoticus. This specific form has been encountered only in Galli (three of the four families). It has been so well described by Hadley, Smith, Morse and Cushman that it is unnecessary to discuss it since we have nothing to add to its pathogenesis or pathology. At a later time some attention will be given to our experience with Quail disease. What is more interesting from a comparative standpoint, besides having a bearing upon blackhead, is the discovery of heterakis in the ceca, and hemorrhage and fatty change in the liver without amœbæ or coccidia in either place (unfortunately no bacteriology was done), in a Sebastopol Goose (_Anser domesticus_), a bird which has ceca not unlike the gallinaceous varieties. This is a single observation and must be treated expectantly.

Microscopically the avian digestive tract in its various inflammatory states presents a few noteworthy features. The primary reaction, sometimes the only one, to irritation is injection of the vessels in the villi or deeper mucosa. To this, however, is nearly always added a granularity of the epithelium, without much evident mucus (goblet cell) formation. When the epithelial degeneration is marked there appears a round cell increase in the deep mucosa shortly followed by a similar infiltration into the villi. True catarrhal enteritis as described for the cats is not as common as some combination of the changes just detailed, but when it occurs is best developed in the carnivorous avian tract. The most striking cellular finding is the round cell of the infiltrate. It is of the middle lymphoid size with clear protoplasm, or, when late in the disease, may be small and so-called adult. Polynuclears, unless eosinophilic, and endothelioid cells are rare.

The foregoing are general remarks concerning the pathology of the avian tract, and we are now ready to discuss briefly the reactions of the orders. I shall, however, omit mention of those in the right half of Table 11.

Passerine birds are represented better than any other order because they are more numerous in nature and therefore exhibited more generously in collections. This order is not especially vulnerable as to its alimentary tract, but this tube is often affected by tiny stones, bits of rust from cages and by acute general nonspecific infections to which these birds are quite susceptible. Upon many occasions intense congestion with and without tiny hemorrhages in the duodenum are all that can be found in the little birds and the diagnosis of enteritis is put down. Only about one-tenth of these birds have shown more or less definite catarrhal changes. Many birds have heavy infestation with worms which may activate bacteria.

The Striges and the Accipitres will be discussed together because of the similarity of their tracts and their diets. The reaction of their gastric complex has already been mentioned and what was written there can be extended to the intestine. The type of lesion is catarrhal and seems to be “meat bred” although this cannot be proven. They never have given positive heart’s blood cultures so that the disease seemed not to be septicemic. Liver and spleen have harbored colon and paracolon bacilli. It will be noticed that they have the highest incidence of gastric disease.

Psittaci, birds with a tract similar to the last two but with a captive diet of seeds, fruit and vegetables although they may eat small animals and insects in the wild, present figures under bacteria and parasites which explain the involvement of the alimentary organs. We have had two acute outbreaks of what seemed to be fowl cholera, judging by the pathology and the isolation of _Bact. gallinarum_ and we have frequent deaths with the same gross anatomy from which bacterial isolation has not been tried or was unsuccessful. At all events the enteritis of parrots is often a definitely infectious affair. We have also isolated _Bact. psittacosis_ on two occasions. Separation of the birds and cleansing of the exhibition spaces seemed to stop the disease. The lesions are hemorrhagic and superficially necrotizing in this group whether or not they are septicemic. Some have also shown a follicular appearance both grossly and minutely, one of which cases was associated with _Bact. psittacosis_.

The effect of animal parasites is chiefly exerted, for this group, in the proventricle where the S_piroptera incerta_ occupies the lumen and penetrates the mucosa or burrows under the inner lining of the gizzard. Enteritis is not especially associated with this infestation, death resulting more from inanition than infection; some few cases have had enteritis, others pulmonary disease.

Columbæ are not susceptible to disease in the parts under consideration. This order seems to have some tissue resistance, for their lesions are quite frankly catarrhal, more so than in most grain-eating birds.

The figures set against the Galli are swollen by the number of cases of enterohepatitis of one sort or another. Extracting these from the total leaves the order among the lowest. Their lesions are congestive and hemorrhagic, although they may show catarrhal cases. They seem to be able to summon mucus more readily than many other birds.

Anserine birds, though not very high in figures, present three conditions worthy of note. In the first place, acute simple gastritis occurs often, sometimes associated with foul green food, sometimes without any apparent cause. From the number of times that foreign bodies are present it seems probable that they contribute in some way. Excessive stones and sand, bits of glass, collar buttons and the like are sometimes found. Then the form of acute enteritis has always a hemorrhagic tendency, at least in the submucosa, while the mucosa may be swollen, opaque and covered with mucus. Upon histological study these intestines show intense swelling by cellular infiltrate and disappearance of the tips of the villi. The third observation concerns what is apparently a subacute or chronic process although this is not supported by microscopy. Certain birds will have a cast of mucus and epithelial detritus rather closely adherent to the wall. Under the microscope there may be slight evidence of chronic inflammation or there may be little amiss. These birds have usually been large ones, and several have come from the separate goose pens, not from the open lake where many birds are kept.

The struthious birds deserve a word. They have had a great deal of enteritis and mostly of infectious nature. Two instances have arisen from bird diphtheria, one from cholera and six from what later seemed to have been anthrax but was not diagnosed at the time. The character of the lesions in the struthious intestine tends to be hypertrophic and superficially erosive if not ulcerative. The changes are found with greatest clearness in the lower duodenum and small coil.

CONSTIPATION.

Having discussed the inflammatory conditions of the gastrointestinal tract we now come to the more or less definitely mechanical abnormalities, whether or not they depend upon preëxisting inflammation, and the subject of constipation will claim first attention. In the human being this condition is the result of bad habits more than any other one thing or all things together, I think it will be admitted. In the lower animals perhaps no such thing as habit of defecation exists so that one can with more certainty hold incorrect food, chronic catarrhs or physical obstruction as responsible. Veterinarians look upon excess of dry food and irregularity of work and food periods as the principal causes of constipation. These factors do not hold in zoological collections. As a matter of fact constipation is of minor importance in this menagerie, but a certain few cases are worthy of note. It has been mentioned in the diagnoses in only a little over 1 per cent. of the total, and of these the records indicate its importance only ten times (.2 per cent.); a few notes of these cases are appended. The first place of incidence is taken by marsupials (six kangaroos and one opossum), the second by ungulates (largely ruminants) and the third by Primates. It will be noted that with exception of the opossum, herbivorous mammals occupy the first places of incidence, carnivores falling well behind the orders named. This condition is quite infrequent in birds and is usually associated with the presence of seeds or parasites or with impaction in the ceca.

Primates, almost exclusively feeders upon carbohydrate and soft protein food, have shown as causes of constipation two outstanding conditions. A low grade of colonic catarrh with excessive pouchings of this tube has had constipation associated with it three times. One of these cases had small coproliths in the diverticula, one other a fecal concrement in the cecum. Another group of these cases with evidence of delayed passage of feces shows chronic peritonitis with adhesions, one of which seems certainly due to filaria in the peritoneal sac.

The seat of constipation in monkeys is practically always the colon. The carnivores while occasionally showing hard fecal masses packed into the colon, more often exhibit a constipation in the ileum. One case presented a nearly empty colon with a long scybalum just above the cecal valve. There is no peculiar associated pathology in the notes at my command.

Ungulata, showing next to the highest incidence, has its stoppage chiefly in the colon, but the lowest stretch of the ileum may contain balls of feces. In nearly every case one finds some grade of colonic catarrh. In two instances, there being a proctitis, it seemed as if the animal voluntarily restrained from defecating because of pain. The caput coli is the seat of stoppage in the Rodentia.

Marsupials give such a high relative incidence that especial search of their records was made, without, however, very definite result. In three of the seven cases an acute general infection existed, in one an acute peritonitis which seemed to emanate from a small ulcer in the ileum, in one an injury to the anal region was found while in the remaining two the notes would suggest that the lower intestine was atonic, judging by its distention, translucency and pallor. In five the stoppage took place in the large bowel alone, in the others both divisions being affected.

It is often difficult to establish a diagnosis of constipation in birds because many varieties form a long rather dry mass in the lower small intestine, to be moistened in the cloaca for discharge. Still again the groups with capacious ceca are apt to have them filled normally with firm casts. Diagnoses of fecal inspissation and stoppage in the smaller tube have been made seldom, but one must consider also the obstruction offered by excessive urate collections either in the cloaca or lower ileum which will amount to a constipation if the cloaca be over-dilated and dried urates mixed with dirt or feathers cover the anal opening.

The causes of this condition in birds are usually mechanical, inflammation being found in a small minority of cases. In the small passerine birds, seeds, sand, or parasites form the commonest findings. This is also true of parrots, while excessive urate collections are noted for both these groups. The gallinaceous birds present two reasons for fecal stoppage—disease of the ceca (see pages 205–6) and cloacitis probably secondary to anal closure by excessive urate collection. Uratic stones, varying from one to five millimetres in diameter, have been found in the cloaca in several orders. In only one case, a pheasant, did they cause ulceration and cloacitis. Sand, rust, grains and the like are found frequently, and sometimes in groups of birds, indicating that the specimens had not been put upon the correct flooring or caging. Unbroken seeds may obstruct the lumen.

MECHANICAL OBSTRUCTION.

Although the following is not constipation it is well to cite at this place an experience which amounted to mechanical intestinal obstruction. A number of finches were subjected to postmortem and found to have whole white millet seeds in their intestines, this being the only discoverable cause of death. Investigation revealed that during the night mice ate the canary seed in the pans, leaving only the millet, which the hungry birds consumed whole. Small birds can take a few millet and crack them when eating leisurely, but apparently not when hungry. When the food was removed at night the trouble ceased.

Obstruction by sand is well illustrated by a peculiar form of pica, in a goose, which is worth citing, and calls to mind the sand disease of horses:

Canada Goose ♂ (_Branta canadensis canadensis_).

DIAGNOSIS.—Masses of sand in entire intestinal tract. The general
condition externally and internally is good. The crop is distended
like a sausage, quite firm and the overfilling is obviously due to
sand in which very few stones, which could be called pebbles, are
found. This mass continues into the esophagus making the whole tract
impassable for food. The mucosa is a little pink and dirt-stained in
places but is not visibly inflamed. The gizzard is contracted over a
mass of sand but no food. Sand in more or less definitely packed
condition is found all along the gut tract, in one place in the small
coil it being quite as tight as in the crop and no lumen remaining.
Sand and bits of shale are found in ceca. The organs are apparently
healthy, slightly pale perhaps, but certainly not distinctly anemic.
No infection exists. The aorta, just above renals, has a 15 mm. × 2
mm. pale opacity of same consistency as the rest of the vessel, just
perceptibly higher than surrounding surface.

“Sand disease” has occurred in a Persian Wild Ass (_Equus onager_) causing in this case ulceration, perforation and peritonitis, a Common deer (_Mazama virginiana_) and a Chapman’s zebra (_Equus burchelli chapmani_). The collection of sand is always greatest in the caput coli, but may coat the large bowel to the anus.

Larger and more definitely obstructive physical objects are found in both mammals and birds. We have on record a lion (_Felis leo_) and a tiger (_Felis tigris_), which swallowed pieces of bone large enough to be stuck in the small intestine and completely occlude it. Smaller objects like buttons have been found even in the passerine tract. Worm masses may occupy such a large part of the lumen of the tube as to constitute a physical obstruction. This is definitely less important in mammals than in birds, especially in the passerine order of the latter class.

Dilatation of the intestine aside from that occurring in connection with fermentation, constipation or ileus, in other words chronic atonic dilatation, has not been encountered. Acute dilatation has been found in several orders under the picture known for domesticated animals. Its pathology and incidence have already been discussed.

ILEUS.

Ileus or acute intestinal obstruction may be divided for our purposes into intussusception, volvulus, strangulation and paralysis from interruption of mesenteric circulation. Examples of all these varieties have been encountered and illustrative cases will be cited. In so far as incidence is concerned, the Ungulata and Carnivora greatly outnumber all other orders, showing seven cases each; the sum total in all other orders is but eight. Upon re-reading some of the protocols I have, however, excluded three invaginations in the carnivores, one each in the ungulates and rodents, as probably being postmortem or shortly antemortem occurrences; two had very early peritonitis but other things, sufficient to account for death, were present. These deductions bring the total cases of ileus in mammals to seventeen. Five cases in birds will be discussed briefly.

Primates present one case of volvulus, one of intussusception and one of internal strangulation. The first displayed the entrance of four inches of ileum into the colon with such swelling of the wall as to prevent reduction. The exciting cause seemed to be an enteritis, the cause of death a peritonitis. A white-collared mangabey (_Cercocebus collaris_) was the victim of volvulus probably favored by an anomalous position of the transverse and descending colon which lay to the right, the latter traversing the abdomen obliquely from right to left to reach the pelvis. The volvulus occurred in the ileum just above the cecum, the twisted part being found adherent by the peritonitis. The third case is a strangulation due to peritonitis from filaria and adhesions between stomach and colon from a colitis and pericolitis due to cestodes, one of which was found deeply implanted in the colonic wall.

Two cases of intussusception are noted (after deductions above) for the Carnivora. They both occurred in the ileum, one restricted thereto, the other extending into the colon. In both a vague history of being “off their feed” or giving evidence of intestinal trouble could be obtained from the keeper. The three excluded cases had invaginations in the middle and lower small intestines but not at the cecal valve. Volvulus did not occur in the Carnivora.

A paradoxure (_Paradoxurus hermophroditus_) died as the result of a strangulation of a six-inch knuckle of gut which had passed through a hole in the omentum. The animal had not been eating well for a month but gave no signs by which this ileus could have been diagnosed. Perhaps it had existed for sometime but only shortly before death had swollen sufficiently to cause obstruction.

Having excluded a doubtful invagination in a small rodent there remains an interesting though somewhat obscure case in a porcupine (_Erethizon dorsatus dorsatus_). This animal suffered with an acute hemorrhagic and catarrhal enteritis while the colon seemed free of change until the rectum was reached. Here was a stretch of a foot with the purple, lusterless but translucent appearance of a strangulated intestine although no involution or twisting remained. This was looked upon as a volvulus which had untwisted a few hours before death.

Intussusception was seen only once in the Ungulata, a tapir (_Tapirus terrestris_) with chronic enteritis. Here the ileum had passed into the colon for a distance of nine inches, it being much swollen and congested but not gangrenous. Its condition warranted the idea that the process was antemortem but a peritonitis had not arisen, death having occurred from the slight extra shock in an animal suffering with chronic malnutrition. Volvulus was encountered three times, two deer and a zebra. The last was the animal already described that carried such a heavy load of sand in the gut tract, a factor in the production of the twist probably although this might have been aided by a fibromyoma of the colonic wall. The location of the volvulus in this order was twice in the dilated descending colon, the third in the jejunal area. This last was a twist which resembled an internal strangulation because of the intricate knot-like windings of the small bowel.

The marsupials present two interesting cases. A rock kangaroo (_Petrogale pencillata_) had chronic gastric ulcerations with local peritoneal adhesions which apparently obstructed nearby coils of intestine so that they became inflated and twisted over. An opossum had a volvulus of the stomach which performed one and a half turns from left to right; its protocol follows.

Common Opossum ♂ (_Didelphys virginiana_). Ileus. One and one-half
complete volvulus turns of stomach on duodenum. General condition
fairly good. Abdomen quite prominent, a condition found to be due to
great dilatation of the stomach which occupied the whole anterior part
of the abdominal cavity. The organ is blue and the vessels stand out.
Postmortem changes are occurring everywhere favored by the obstruction
to the circulation. The dilated stomach has undergone a volvulus upon
the third part of the duodenum making one and a half turns. The spleen
lies upon the right side well below the liver; it is swollen, soft and
deep purple. The duodenum in its upper half takes part in the
dilatation and beginning gangrene. The pedicle of the twist is made of
the duodenum, esophagus, edge of the mesentery and the middle part of
the pancreas; the end of the tail of the last is gangrenous. There is
no apparent obstruction lower down to explain the twist of the
stomach.

Among the Aves the following cases only are worthy of report. A parrot (_Melopsittacus undulatus_) was found to have a tightly packed mass of worms in the end of the duodenum above which the bowel was distended, elongated, doubled on itself and of a deep red color; below this the small intestine was empty. A closely similar condition was found in a Screech Owl (_Otus asio asio_) the obstruction occurring just above the end of the small gut. A Sparrow Hawk (_Falco sparverius_) had an invagination two cm. in length, a short distance above the end of the small intestine. No peritonitis existed but the presence of an acute enteritis helps to explain the intussusception.

HERNIA.

Hernia is not a common occurrence among the lower animals but our experience is instructive in two particulars, to wit, its absence in the orders preceding the Rodentia and the frequency of the traumatic variety. There being no general remarks to be made upon the subject, it seems well to give a summary of the findings in each of the seven cases.

A Western Fox Squirrel (_Sciurus rufiventer_) showed a diaphragmatic defect on the right side, a rounded opening with smooth edges, through which a loop of intestine had passed, entering behind the liver and reaching into the pleura as high as the pulmonary apex where it was adherent; this was probably of long standing. Two more loops were found wedged in the diaphragmatic hole, one of which was gangrenous.

An Indian Antelope (_Black Buck_) (_Antilope cervicapra_) presented an irreducible incarcerated but not strangulated umbilical hernia. The peritoneum was fused with the aponeurosis at the ring but the gut was not adherent at this point while it was attached within the sac outside the muscle, thus forming the incarceration. Apparently the sac had dissected between the muscular layers for it could be followed for several centimetres in some directions. A Hog Deer (_Cervus porcinus_) had apparently suffered an injury in the flank for at one point the muscles were irregularly cicatrized and a rent was present through which several loops of intestine and a band of omentum had escaped, being adherent to fascia. No injury to the skin was apparent.

Another Indian Antelope showed a clean traumatic rupture of the muscle _and peritoneum_ in the right inguinal region _without_ penetration of skin. An acute hernia had occurred which was lightly adherent to fascia and an acute peritonitis was beginning. The bowel was however not strangulated.

An aoudad (_Ovis tragelaphus_) seems to have suffered an injury by a pointed object (horn?) just to the right of the ensiform cartilage for at this position there is a circular hole, with smooth healed edges, in the aponeurosis, permitting the emersion of a peritoneal sac containing omentum. All parts were adherent but no acute inflammation existed.

What may have been a hernia or a relaxation of the transversus perinei was observed in an Undulated Grass Parrakeet (_Melopsittacus undulatus_). A bulge about the size of the finger end was seen externally, beside and behind the anus. This proved to contain several loops of bowel and a mass of fat.

A lateral abdominal hernia was seen in a Barbary Turtle Dove (_Turtur risorius_). It consisted of a peritoneal sac and two loops of intestine. This protrusion, while firmly fixed in its unnatural position, was in no way constricted.

RECTAL PROLAPSE.

Prolapse of the rectum may in a sense be looked upon as a hernia or at least as a relaxation of the anal and perineal muscles with protrusion of parts normally situated intracorporeally. Although not frequent it has been incurable in the animal, as it frequently is in man without operation, a measure we have not adopted. Just what determines weakness in the pelvic outlet is entirely obscure for indeed we have seen here wounds and inflammations of the perineal area without prolapse of the rectum and in none of the cases of prolapse did the pelvic floor seem injured or diseased. It is but speculation to blame the annular muscles of the anus. Tenesmus, or at least reasons for this straining action, have been sought, with the result that in our cases lesions of the egg- laying apparatus in birds and enteritis in mammals have stood out most prominently. In no case have hemorrhoids been encountered nor has a tumor pendant from the colonic mucosa, drawn the bowel toward the anal opening. It might be added parenthetically here that hemorrhoids are practically unknown for quadrupeds, Hutyra and Marek failing to mention them independently and only one reference being found in the _Jahresbericht fur Veterinär Medizin_ (Schmidt 1914–169); this case is more like angioma than hemorrhoids. If tenesmus be active in the production of rectal prolapse then it would have to be assumed that this straining effort can be induced by enteritis since eversion of the rectum has occurred with this disease in the absence of colitis, the condition usually expected in the presence of tenesmus. The thirteen cases have been seen in Mammalia, 8, (Carnivora, 2, Rodentia, 1, Ungulata, 3, Edentata, 1, Marsupialia, 1) and Aves, 5, (Passeres, Picariæ, Striges, Psittaci and Galli each one). Three mammals had enteritis, one had foreign bodies in the bowel and one had many ascarids; three had no demonstrable or suggestive causes. Two of the five birds had enteritis high in the tract, one had uratic calculi in the cloaca, and three had trouble in the egg-laying apparatus: one too large an egg, one a broken egg and one a salpingitis.

DIVERTICULA.

It is almost certain that in a human pathological service of fifty-five hundred autopsies, one or more diverticula of the Meckel variety would be encountered and perhaps several of other kinds. In our material only pouchings or false diverticula of the colonic wall are recorded, and our personnel has often spoken of the absence of these gross abnormalities of the alimentary tract. The two cases, notes of which are given, are instances of hernial pouchings of the colonic mucosa and serosa, a condition which is well known in human medicine. It may be said to occur in two varieties, one in which the pouchings have heavy walls formed by a thickened mucosa, muscularis and peritoneum and one in which the bulgings have delicate walls, then being small herniæ of the inner coats through rifts in the outer. Such a division is probably unnecessary or misleading since the latter may be only a forerunner of the former. However the clinical evidence of the simple variety is scanty and may be little more than constipation while the peritonitic variety gives a clinical picture of pain, constipation and a mass in the left abdominal area, then known as diverticulitis or pericolitis sinistra. In these cases the colon is much distorted by the irregularity of its mucosa and by inflammatory thickening of the muscularis and serosa. Diverticula arise from defects of the muscular coat, or secondarily after inflammation or prolonged constipation, by weakness of muscle, or as hernial protrusions around the entrance of blood vessels where the muscle is thin. Such sacculations permit feces to collect and continue the inflammation, thus further weakening the gut and producing constipation, the whole vicious cycle being favorable to the formation of more sacculations; coproliths may form in the diverticula. The two monkeys now reported seem to have varying grades of the same condition, a long standing colitis with diverticula, constipation and the collection of inspissated feces in the sacculations. These animals did not have hemorrhoids.

Black Ape ♀ (_Cynopithecus niger_). Coprostasis. Coproliths in
diverticulum. Chronic colitis. Cor bifida. The large intestine is of
the same calibre as the small intestine should be when not distended.
The sacculations as seen before opening the organ are salient, forming
distinct pouches. In one or two cases they are so pronounced as to
constitute diverticula 7 cm. long. In two instances the serosa at the
fundi of these diverticula is markedly hyperemic and very thin. In
many cases the sacculations contain coproliths. The wall of the organ
is distinctly thickened, puckered, inelastic and opaque. Mucosa is
thrown up into coarse rugæ.