Part 18

Gastric ulcer, so-called peptic or round ulcer of the stomach, having a chronic course and leading to radiating scars of the mucosa is not common in the lower animals, but frequent enough in the human being. The form of ulcer in question has at present no adequate explanation, or at least there is no one cause which will answer for all cases. Local injuries from within or without the stomach, bacterial embolism, entrance of bile through the open pylorus and many other factors have been named in the causation but can seldom be used in any given case. In the lower animals with their relatively frequent parasitic infestation, another factor is added. In analysis of our statistics I have separated ulcerative gastritis from parasitic and mycotic ulcerations and from peptic ulcers; the first is discussed in later paragraphs. Parasitic ulcers of the stomach occur chiefly in our native marsupial, the opossum, and in some Carnivora; physaloptera, strongylus, ascaris, and gastrophilus have been found. The kangaroos are frequently affected (8 cases) with an acute or subacute ulceration of the gastric wall, without much general gastritis. The lesion is peculiar in appearance. The youngest ulcers are black or dark gray, flat necroses of the mucosa alone and indeed the process very frequently penetrates no deeper. Older lesions spread laterally and may be preceded by a very narrow congested line but there is no raised edge nor does there seem to be submucous infiltration. If the process be rapid a loose dirty slough may form. Certain of the advanced cases of Kangaroo mycosis will present more infiltrative lesions of the gastric wall leading to large and well defined necrotic areas; they may at times penetrate the whole wall outward. (See page 580.)

True peptic ulcers have been found in Primates, 4; Carnivora, 5; Pinnipedia, 2; Insectivora, Ungulata and Hyraces each one. The London Garden reports that gastric ulcerations occur most often in Carnivora and Marsupialia. Those in the last three orders of our list were small, usually multiple and relatively superficial. The ulcers found in Primates and Carnivora present the usual pictures seen in man. In one example in each of these orders radiating scars of healed defects are mentioned in the notes. None of them seems to have led to cancer, and in only one, a wolf (_Canis lupus_), was the scar tissue sufficient to cause definite impediment to the motility of the stomach. Six of the fourteen examples appeared on the greater curvature, the remainder on the lesser. Ten ulcers were in the pyloric division, the other four being scattered. No other pathology is found common to these cases which might be drawn into etiological association.

TUMORS.

Tumors of the gastric complex are not at all common, there being only the following to report: Primates, Hamadryas Baboon (_Papio hamadryas_), diffuse adenoma; (none in Carnivora with the most ulcers); Marsupialia, Red Kangaroo (_Macropus rufus_), malignant papilloma with metastases. The former tumor, shown in Fig. 17, was a diffuse soft excrescence beginning near the pylorus and stretching along the lesser curvature toward the cardia. Histologically it was made up of glandular acini growing in all directions but always maintaining normal relations of cells and basement membrane. There were no metastases and other reasons for death existed. The tumor of the kangaroo stomach was a true epitheliomatous cancer with metastases to liver, spleen, and kidney. Only one secondary tumor was observed, from a carcinoma of the lung in a Red Kangaroo (_Macropus rufus_).

THE INTESTINE.

Inflammation of the gastrointestinocolic tube is the most important single condition with which handlers of animals have to deal, and unfortunately it can seldom be diagnosed clinically, early and accurately enough, to make treatment useful. At this Garden some evidence of acute or chronic disease of the tube has been present in 31 per cent. of our autopsies. The reports of other gardens would indicate that their figures might be quite close to this. What is the cause of this high mortality? Incorrect feeding, qualitatively or quantitatively has been put at the top of the list by Plimmer, but he adds other less important factors: Bacteria of infectious power, protozoa, foreign bodies and parasites or their mural cysts. In order to evaluate approximately how each of these acts let us review the causes as they are generally known and later discuss the pathology as seen in the various orders.

(1) Overloading of the stomach by too much food or by rapid eating of a hungry animal is of importance under certain domestic circumstances where times of feeding are irregular or intervals are too long, but this cannot occur in any well regulated menagerie. It is possible, however, that overfilling might occur in certain Ungulata, which have hay and straw nearly always available, if the food in their reach happens to be particularly agreeable or tasty to them.

(2) Insufficient mastication would seem to be important only in those orders which depend upon this action to triturate, insalivate and macerate their food, of which Homo, Primates, Ungulata and Marsupialia are the principal ones.

(3) Disturbance during and after feeding has always been believed to affect digestion unfavorably, and it may be that visitors to a collection exert such an effect; this factor is probably negligible.

(4) The appropriateness of the food is a very important factor in the health of an animal under captive conditions. Diet lists are made up by officials largely according to the known habits and general physiology of an animal, but the food offered can at best only approximate what the wild beast obtains for himself. It does not follow because a selected diet may seem to provide all the elements contained in the food available under natural conditions that it actually does so, especially since we are aware that some essential food factors, known under the term vitamins, are necessary to best development. These substances vary in closely similar foods, and seem to be higher in simple natural foods than in prepared diets. We have seen in this Garden that the inorganic constituents must be correctly represented in the food, else degenerative osseous condition may develop. Inappropriate diet may express itself at once after the receipt of an animal, by its sickness or death, or after some time in the development of chronic tympanites, chronic intestinal catarrh or bony deformities.

(5) The physical condition of food is a matter of no small moment. The taking of soft food in large quantities especially by herbivorous animals, permits too short a sojourn in the gastric fundus and is often followed by pyloric and duodenal disease. Too firm food may pack the rumen, fundus or proventricle as the case may be, and be succeeded by distention of these parts and catarrh of the pyloric and intestinal area. The effect of foreign bodies mixed with food is difficult to evaluate unless of course they be of such a nature (pointed metal and the like) as directly to traumatize the mucosa. Many birds and mammals come to autopsy with a relatively large number of stones and small sticks in the stomach without any distinct evidence that they have been hurt thereby. In the bird the stones may be so large and numerous as to leave little room for food, or small enough to pass out into the intestine where they undoubtedly may pave the way for bacterial action. Smoothly polished pebbles in small quantity seem to have little effect in mammals. Hair balls are not common and unless of large size are apparently unimportant. Considerable sand mixed with food has a distinctly irritating effect. It is perhaps best known as a chronic gastric disorder of horses; we have seen it in zebra.

(6) Spoiled food is obviously a very prime factor in inflammations of the gastrointestinal tract. Its operations are illy understood except perhaps when products of fermentation or putrefaction prevent digestive action or are absorbed. If in small quantities not sufficient to cause acute fermentative inflammation or intoxication, such substances frequently taken may doubtless produce chronic catarrhs. Many animals are fed upon vegetable mashes, or stews which can decompose, while bad meat may occasionally be fed. We had a rather serious outbreak of enteritis in small Carnivora from the use of fowl heads obtained at hotels; some of these cases were shown to be due to B. paracoli, thus to be looked upon as infections. Dirty food while not spoiled may carry with it organisms of decomposition, or of infective qualities, or the dirt may act as an irritative foreign body. We have found that for delicate ungulates (antelopes) it is highly desirable to screen grain, and that the grade of hay should be of the best.

(7) Infectious conditions are of great importance under certain circumstances but with the exception of hog and fowl cholera, the dysenteries and a few other diseases, do not as a rule play a great part in mortality as specific diseases unless of course an epizoötic appear. The greater problem is to understand bacterial action in the face of other factors. Are infectious germs introduced with food and drink in every case of gastroenteritis or do some other factors activate those already present in the gut tract? Unfortunately these questions cannot be answered directly. We can, however, point out which groups of bacteria are most common in some of the orders, which orders are most susceptible to bacterial invasion and which to local lesions with intoxication. The greatest problem in the field is the interrelation of germs of various sorts in the intestinal tract. Certain varieties are known to develop intoxicating aromatic substances, others to elaborate or excrete fatty acids, still others to form antiferments but the conditions existing in the various kinds of intestinal tracts are too little understood to help very much in this study.

(8) Animal parasites have long been considered as one of the causes of gastrointestinal inflammation, a condition largely due to copying from book to book of a few facts and more impressions. The sum of reliable information to-day would seem to indicate that a few parasites—uncinaria being the most conspicuous example of this type—draw considerable blood from the mucosa, that a few, like uncinaria and dibothriocephalus, elaborate an absorbable toxin, that some, notably ascarids, produce an irritating substance, and that many possess the power in themselves or by some excretion to act as antiferments. These factors, were they all combined in one worm, might probably irritate the mucosa sufficiently to produce inflammation, but it is not easy to imagine that they would cause an acute specific condition. It is much more easily conceived that with tiny hemorrhages or ulcerations of mucosæ, bacteria might get in their work or if considerable ferment were neutralized, maldigestion, flatulence or indigestive irritation would ensue. With certain worms like esophagostomum there is considerable evidence to show that a chronic fibrous disease of the intestinal wall arises, but in this case the parasite resides in the mucosa and acts as a foreign body. It would seem, however, that the most important influence that animal parasites exert is to be found in the preparation of the mucosa for the action of bacteria. Masses of parasites may of course physically obstruct the lumen and lead to intestinal stasis and dilatation.

INFLAMMATION.

In analyzing the cause of a gastroenteritis and its consequent effect upon the wall of the tube and upon the viscera, certain physical, chemical and physiological factors must be considered. Whether this may be directly the effect of bacteria or poisons from worms or some other factor seems of little moment since in any fully developed case, symptoms and effects are comparable. Moreover it seems that pathological anatomy, both gross and minute, is essentially the same from Primates to struthious birds, the highest and lowest of the two classes here considered. By this is meant that the acute congestive condition of the gut tract with solution of the surface, to which we have applied the name of toxic enteritis, seems to be met with in this form throughout all the orders. So too catarrhal inflammations are the same to the naked eye and under the microscope, due allowance being made for the fact that mammals use polynuclear cells for exudative purposes while birds employ mononuclears. Concomitantly with these conditions, a degenerative process may be going on in the liver and kidney, and hyperplasias, especially in the true infective processes, will be found in the related lymphatic structures.

The majority of students to-day place responsibility for gastroenteritis upon the bacteria known to be present in the various intestinal tracts, mentioning especially colon and proteus groups, streptococci, the necrosis bacillus and anaerobes of the Welch class. In a few of our studies of intestinal bacteria in cases of enteritis one thing has been very definite and that is that in the intestinal content of animals whose food is largely meat, Gram-negative bacilli have predominated, whereas in herbivorous animals Gram-positive organisms have been most numerous. From the observations of Kitt, Strassberger and some others, the normal flora of domesticated animals is subject to wide variations so that our observations must receive confirmation before they are finally acceptable. We have on several occasions isolated from carnivorous intestines Bact. paracoli, Bact. suipestifer and other members of this group. We have no reliable cultural data upon the herbivorous intestine and can only quote the Gram pictures as mentioned above. On two occasions, an eland and an elk, a very large number of forms corresponding to necrosis bacillus were seen; to this organism Kitt gives considerable power in the production of necrotizing processes.

TABLE 11.

_This table shows an analysis of all cases of gastroenterocolitis. The left half of the table is an analysis of orders upon which one hundred or more autopsies have been done, the right half of orders with fewer than that number. The left half is expressed in percentages, the right half in number of cases only since percentages might be misleading. Left hand table: First column is percentage of gastroenterocolitis per order; next five columns the percentages in which each of the factors in the headings was believed responsible; the last three columns show the participation of each of the divisions of the intestinal tract; thus Primates had all told 24.8 per cent. of inflammations of which 7.2 per cent. were in stomach, 18.3 per cent. in the intestines and 8 per cent. in the colon; obviously many had all three sections affected. Right hand table is constructed on a similar basis except that number of cases is quoted, not percentages, and the total is put in the last column._

════════════╤═══════════════════════════════════════════════════════ │ Percentages in orders with sufficient autopsies. ────────────┼─────────┬────┬────────┬─────────┬────────┬──────────── │Per cent.│Food│Bacteria│ Animal │Physical│Undetermined │ of │ │ │Parasites│Objects │ │Autopsies│ │ │ │ │ ────────────┼─────────┼────┼────────┼─────────┼────────┼──────────── Primates │ 24.8│ 1.8│ 4.4│ 3.6│ │ 15. Lemures │ │ │ │ │ │ Carnivora │ 46.1│ 2.9│ 7.2│ 5.8│ .2│ 30. Pinnipedia │ │ │ │ │ │ Insectivora │ │ │ │ │ │ Chiroptera │ │ │ │ │ │ Rodentia │ 25.│ 5.│ 2.│ 2.│ │ 16. Ungulata │ 24.8│ 6.6│ 2.2│ 2.│ .8│ 13.2 Proboscidea │ │ │ │ │ │ Hyraces │ │ │ │ │ │ Edentata │ │ │ │ │ │ Marsupialia │ 33.1│ │ 10.│ 10.1│ │ 13. Passeres │ 23.6│ .1│ 4.5│ 1.8│ .15│ 17. Picariæ │ │ │ │ │ │ Striges │ 41.5│ 1.5│ 5.3│ .7│ │ 34. Psittaci │ 36.6│ .3│ 10.7│ 3.7│ .15│ 21.8 Accipitres │ 40.7│ │ 4.5│ │ .5│ 35.7 Columbæ │ 17.8│ │ .6│ 3.│ .6│ 13.5 Galli │ 38.6│ │ 5.3│ 19.6│ │ 13.7 Hemipodii │ │ │ │ │ │ Fulicariæ │ │ │ │ │ │ Alectorides │ │ │ │ │ │ Limicolæ │ │ │ │ │ │ Gaviæ │ │ │ │ │ │ Impennes │ │ │ │ │ │ Steganopodes│ │ │ │ │ │ Herodiones │ │ │ │ │ │ Odontoglossæ│ │ │ │ │ │ Palamedes │ │ │ │ │ │ Anseres │ 29.6│ .3│ 4.4│ 2.3│ .6│ 22. Struthiones │ │ │ │ │ │ Crypturi │ │ │ │ │ │ ────────────┴─────────┴────┴────────┴─────────┴────────┴────────────

════════════╤════════════════════════╤════════════════════════════════ │sufficient autopsies. │Number of cases in orders with under 100 autopsies each. ────────────┼───────┬──────────┬─────┼────┬────────┬─────────┬──────── │Stomach│Intestines│Colon│ │Bacteria│ Animal │Physical │ │ │ │Food│ │Parasites│Objects │ │ │ │ │ │ │ ────────────┼───────┼──────────┼─────┼────┼────────┼─────────┼──────── Primates │ 7.2│ 18.3│ 8.│ │ │ │ Lemures │ │ │ │ │ 8│ 2│ Carnivora │ 21.│ 41.│ 6.6│ │ │ │ Pinnipedia │ │ │ │ │ 1│ 1│ 1 Insectivora │ │ │ │ │ │ │ Chiroptera │ │ │ │ │ │ │ Rodentia │ 7.│ 20.5│ 3.5│ │ │ │ Ungulata │ 9.1│ 20.│ 2.5│ │ │ │ Proboscidea │ │ │ │ │ │ │ Hyraces │ │ │ │ │ │ │ Edentata │ │ │ │ │ │ │ Marsupialia │ 22.│ 21.│ 3.5│ │ │ │ Passeres │ 1.2│ 22.│ 3.│ │ │ │ Picariæ │ │ │ │ 1│ 10│ 4│ Striges │ 6.│ 40.│ .7│ │ │ │ Psittaci │ 1.7│ 35.4│ 1.3│ │ │ │ Accipitres │ 5.2│ 39.│ 1.│ │ │ │ Columbæ │ 4.5│ 13.5│ .7│ │ │ │ Galli │ 2.6│ 21.6│ 19.6│ │ │ │ Hemipodii │ │ │ │ │ │ │ Fulicariæ │ │ │ │ │ 6│ 1│ Alectorides │ │ │ │ 1│ 1│ 2│ Limicolæ │ │ │ │ │ │ │ Gaviæ │ │ │ │ │ 1│ 1│ Impennes │ │ │ │ │ │ │ Steganopodes│ │ │ │ 1│ 1│ │ Herodiones │ │ │ │ │ 1│ 3│ Odontoglossæ│ │ │ │ │ │ │ Palamedes │ │ │ │ │ │ │ Anseres │ 2.5│ 27.7│ 6.6│ │ │ │ Struthiones │ │ │ │ │ 7│ │ Crypturi │ │ │ │ │ │ │ ────────────┴───────┴──────────┴─────┴────┴────────┴─────────┴────────

════════════╤═════════════════════════════════════════════════════ │Number of cases in orders with under 100 autopsies each. ────────────┼────────────┬───────┬──────────┬─────┬─────────────── │Undetermined│Stomach│Intestines│Colon│ Total Animals │ │ │ │ │ Showing │ │ │ │ │Gastroenteritis ────────────┼────────────┼───────┼──────────┼─────┼─────────────── Primates │ │ │ │ │ Lemures │ 13│ 4│ 19│ 3│ 23 Carnivora │ │ │ │ │ Pinnipedia │ 8│ 7│ 8│ 1│ 11 Insectivora │ │ │ │ │ Chiroptera │ 2│ 1│ 1│ │ 2 Rodentia │ │ │ │ │ Ungulata │ │ │ │ │ Proboscidea │ 1│ │ 1│ │ 1 Hyraces │ 2│ │ 1│ 1│ 2 Edentata │ 2│ │ 1│ 1│ 2 Marsupialia │ │ │ │ │ Passeres │ │ │ │ │ Picariæ │ 24│ 5│ 36│ │ 39 Striges │ │ │ │ │ Psittaci │ │ │ │ │ Accipitres │ │ │ │ │ Columbæ │ │ │ │ │ Galli │ │ │ │ │ Hemipodii │ │ │ │ │ Fulicariæ │ 8│ 1│ 15│ │ 15 Alectorides │ 10│ 2│ 13│ 3│ 14 Limicolæ │ 1│ │ 1│ │ 1 Gaviæ │ │ │ 2│ │ 2 Impennes │ 3│ 1│ 3│ │ 3 Steganopodes│ 8│ 1│ 10│ │ 10 Herodiones │ 25│ 1│ 24│ 6│ 29 Odontoglossæ│ │ │ │ │ Palamedes │ 1│ │ 1│ │ 1 Anseres │ │ │ │ │ Struthiones │ 14│ 8│ 20│ 3│ 21 Crypturi │ 1│ │ 1│ │ 1 ────────────┴────────────┴───────┴──────────┴─────┴───────────────

THE TABLE.