Part 25

════════════╤═════════════╤═════════╤═════════════╤═════════╤═════════ Order │ Cholangitis │ Hepatic │Inflammation │ Acute │ Chronic │ or │Cirrhosis│ outside │Enteritis│Enteritis │Choledochitis│ │ Pancreas │ │ │ │ │ │ │ │ │ │ │ │ ────────────┼─────────────┼─────────┼─────────────┼─────────┼───────── Primates: │ │ │ │ │ Marmoset │ 0 │ 0 │Lymphadenitis│ 0 │ 0 │ │ │ adjacent │ │ │ │ │ glands │ │ │ │ │ │ │ Carnivora: │ │ │ │ │ Wolf │ + │ 0 │ 0 │ + │ 0 Fox │ 0 │ 0 │ 0 │ ? │ 0 Bear │ 0 │ 0 │ Areolar │ + │ │ │ │ tissue and │ │ │ │ │ glands │ │ Raccoon │ 0 │ 0 │ 0 │ 0 │ 0 Bear │ 0 │ 0 │ Slight │ + │ 0 Coati │ + │ 0 │ 0 │ 0 │ 0 Badger │ + │ Atr. │ 0 │ 0 │ Ocelot │ +? │ 0 │ 0 │ + │ 0 Bear │ +? │ 0 │ 0 │ + │ 0 Wild Cat │ 0 │ 0 │ 0 │ + │ +? Lion │ 0 │ 0 │ 0 │ + │ + Skunk │ + │Infective│+ Lymphnodes │ 0 │ 0 Raccoon │ 0 │ 0 │ 0 │ 0 │ 0 │ │ │ │ │ Rodentia: │ │ │ │ │ Beaver │ + │ 0 │ 0 │ 0 │ + Porcupine │ 0 │ 0 │ Lymphnodes │ + │ 0 Ungulata: │ │ │ │ │ Antelope │ 0 │ 0 │ 0 │ 0 │ 0 Deer │ ? │ 0 │ + │ + │ 0 Deer │ 0 │ 0 │ + │ 0 │ 0 Deer │ 0 │ + │ 0? │ 0 │ 0 Elk │ 0 │ 0 │ Lymphnodes │ + │ 0 Nylghaie │ 0 │ 0 │ 0 │ + │ 0 Peccary │ 0 │ 0 │ 0 │ + │ 0 Marsupialia:│ │ │ │ │ Phalanger │ 0 │ 0 │ 0 │ + │ 0 Opossum │ 0 │ 0 │ 0 │ + │ + Opossum │ 0 │ 0 │ 0 │ + │ 0 Devil │ + │ 0 │ + │ 0 │ + Passeres: │ │ │ │ │ Finch │ 0 │ 0 │ 0 │ ? │ ? Thrush │ 0 │ + │ 0 │ 0 │ 0 │ │ │ │ │ Chaffinch │ + │ 0 │ 0 │ 0 │ 0 Picariæ: │ │ │ │ │ Hornbill │ + │ 0 │ + │ + │ Striges: │ │ │ │ │ Owl │ +? │ 0 │ 0 │ 0 │ + Accipitres: │ │ │ │ │ Kestrel │ 0 │ 0 │ + │ 0 │ + Columbæ: │ │ │ │ │ Dove │ 0 │ 0 │ 0 │ 0 │ + Galli: │ │ │ │ │ Pheasant │ + │ 0 │ 0 │ 0 │ + Fulicariæ: │ │ │ │ │ Gallinule │ + │ 0 │ 0 │ + │ 0 Anseres: │ │ │ │ │ Gadwall │ 0 │ 0 │ 0 │ + │ 0 Struthines: │ │ │ │ │ Ostrich │ 0 │ 0 │ 0 │ + │ 0 ════════════╪═════════════╪═════════╪═════════════╪═════════╪═════════ _Totals_ │ │ │ │ │ Primates │ │ │ 1 │ │ Carnivora │ 4 │ 2 │ 3 │ 7 │ 2 Rodentia │ │ │ │ 1 │ 2 Ungulata │ 1 │ 1 │ 3 │ 5 │ Marsupialia │ 1 │ │ 1 │ 3 │ 2 ────────────┼─────────────┼─────────┼─────────────┼─────────┼───────── _Mammalia_ │ 6 │ 3 │ 8 │ 16 │ 6 Passeres │ 1 │ 1 │ │ │ Picariæ │ 1 │ │ 1 │ 1 │ Striges │ 1? │ │ │ │ 1 Accipitres │ │ │ 1 │ │ 1 Columbæ │ │ │ │ │ 1 Galli │ 1 │ │ │ │ 1 Fulicariæ │ 1 │ │ │ 1 │ Anseres │ │ │ │ 1 │ Struthiones │ │ │ │ 1 │ ────────────┼─────────────┼─────────┼─────────────┼─────────┼───────── _Aves_ │ 4 │ 1 │ 2 │ 4 │ 4 Grand Total │ 10 │ 4 │ 10 │ 20 │ 10 ────────────┴─────────────┴─────────┴─────────────┴─────────┴─────────

════════════╤════════ Order │ Fat │Necrosis │ │ │ ────────────┼──────── Primates: │ Marmoset │ 0 │ │ │ Carnivora: │ Wolf │ 0 Fox │ 0 Bear │ + │ │ Raccoon │ 0 Bear │ 0 Coati │ + Badger │ 0 Ocelot │ + Bear │ 0 Wild Cat │ 0 Lion │ + Skunk │ 0 Raccoon │ small │ Rodentia: │ Beaver │ 0 0 Porcupine │ 0 Ungulata: │ Antelope │ ? Deer │ 0? Deer │ 0 Deer │ 0 Elk │ 0 Nylghaie │ 0 Peccary │ + Marsupialia:│ Phalanger │ + Opossum │ + Opossum │ + Devil │ + Passeres: │ Finch │ 0 Thrush │ 0 │ Chaffinch │ 0 Picariæ: │ Hornbill │ Striges: │ Owl │ + Accipitres: │ Kestrel │ 0 Columbæ: │ Dove │ 0 Galli: │ Pheasant │ 0 Fulicariæ: │ Gallinule │ 0 Anseres: │ Gadwall │ 0 Struthines: │ Ostrich │ 0 ════════════╪════════ _Totals_ │ Primates │ Carnivora │ 5 Rodentia │ Ungulata │ 2 Marsupialia │ 4 ────────────┼──────── _Mammalia_ │ 11 Passeres │ Picariæ │ Striges │ 1 Accipitres │ Columbæ │ Galli │ Fulicariæ │ Anseres │ Struthiones │ ────────────┼──────── _Aves_ │ 1 Grand Total │ 12 ────────────┴────────

Further analysis of the data leads into a consideration of the anatomy of the viscus in terms of the acceptable theories of the origin of the lesion. It is commonly believed that infection of the gland occurs by passage of organisms through the duct opening in the intestines, especially when there is swelling of the mucosa of both. For the human being the idea is current that infection or obstruction of the common bile duct may spread to the pancreatic duct, and that mechanical or inflammatory obstruction of the papilla of Vater may permit the bile to pass up the pancreatic duct. This theory is based upon certain observations, notably those of Opie, in cases, where a gall stone obstructed the ampulla, bile entered the pancreas and acute pancreatitis arose, partly by the activating action of the bile upon the pancreatic juice and partly by bacteria introduced at the same time. This method of origin is perhaps accepted in most quarters, but there are some who believe that infection of the gland may occur by the infiltration of lymphatics around the pancreas by disease of adjacent parts—gall- bladder, stomach or lymph nodes. Quotation has already been given to reference literature, and I shall not go further into theory except in pointing out how our material may help to answer the question.

In the first place it seems perfectly obvious that infection might in any animal travel from the intestine to the pancreas _via_ its ducts, the main question to be settled being the relative importance of the infection _via_ the bile duct. Let us now see if the variations in anatomy will cast any light upon the matter.

Among the 1860 mammals, there are as far as I can determine 1275 which have one pancreatic duct opening in conjunction with the bile duct, 585 in which the former has an intestinal opening independent of the latter. Among this 1275 there are nineteen cases of pancreatitis, while among the 585 there are eight cases, or as 14.9 to 13.6. All Aves have separate biliary and pancreatic ducts and relatively little pancreatitis, although frequently suffering with its most common accompaniment, namely duodenitis. There is therefore some evidence that more pancreatitis occurs when there is a physical proximity or combination of bile and pancreatic ducts.

Active infections of the biliary system in relation to pancreatitis are, however, not as conspicuous as might be expected. In the mammals twelve of the twenty-seven cases showed cholecystitis or cholangitis; in every instance the form of pancreatitis was acute. Among the eleven avian cases four showed inflammation of the biliary channels, but not of the bladder. Hepatic cirrhosis was observed four times. In a thrush and a skunk obvious infectious cirrhosis existed, and in both a necrotizing pancreatitis was found. A badger suffered with atrophic cirrhosis of the liver and a chronic pancreatitis with acute exacerbation. A deer showed marked perilobular fibrosis with a recent hemorrhagic pancreatitis probably due to duodenal torsion. Nothing very distinctive is to be found in these cases, but they merely make the total of involvements of the liver and its adnexa up to twenty. It is to be emphasized that pancreatitis was not associated with lithiasis in ducts or bladder as described on page 240. Peripheral cholecystitis and plastic inflammations about the pylorus and lesser omentum are exceedingly rare in wild animals, while they are not common in human surgical practice. They did not occur at all in mammals in this series, the only external inflammations being in lymph nodes in cases of frank infectious character. There were distinct adhesions between liver, duodenum and pancreas in two birds, one with acute, the other with chronic pancreatitis.

In so far as the kind of pancreatitis is concerned mammals had twenty- two acute and six chronic forms, one animal having the former implanted on the latter, while birds had five acute and six chronic. The preponderance of acute over chronic lesions in mammals again recalls the association of the biliary and pancreatic ducts, but if one expect that such a relation establishes acute inflammation, the relatively high figures for Rodentia and Ungulata, with a single duct removed from the bile duct conflict with the data for orders having two ducts such as the Carnivora. Every case in the former orders was of acute nature; only two had any hepatic disease, four had lymph gland hyperplasia in the pancreatic region, and seven had acute enteritis. The preponderance of acute over the chronic cases in mammals and the nearly equal number in birds is, however, apparent.

The collateral pathology with the most definite relationship to pancreatitis is enteritis and one may say that the former occurs in proportion to the incidence of the latter. Acute forms, twenty-seven, were associated with acute enteritis nineteen times. Chronic enteritis was found with chronic pancreatitis in six of eleven cases.

There is a rough relationship between the type of pancreas and the nature of the lesions. The organ may be divided for this purpose into the compact organ firmly held in place by attachments to the lesser omentum, spleen and duodenum, and the velamentous organ which spreads a considerable distance along the duodenum and sends out digitations into the mesentery and thin processes toward the spleen. The first type is seen in primates and carnivores and birds, while the second is characteristic of rodents, ungulates and marsupials. The compact variety showed all but one of the chronic cases while the loose organ was affected by the acute pancreatitis in twelve of thirteen cases.

The microanatomy of the cases may throw a little light upon our subject. I was able to see the duct in one case of acute pancreatitis (bear). It showed a simple catarrhal inflammation with a very moderate circumferential round cell increase. The destruction of glandular areas by edema, hemorrhage and necrosis offers nothing of importance except in a few birds. In these the necrosis is more definite about cross sections of ducts, and the islands of Langerhans are frequently spared until necrosis is locally complete. In a case of chronic pancreatitis in a bird, a cross section of pancreatic duct was found in the intestinal wall; a chronic catarrhal and infiltrative enteritis existed in this specimen. A very definite mantle of round cells was found about the duct while the mucosa showed no change, although the lumen seemed large. Interlobular fibrosis was the rule, only one case of intra-acinar pancreatitis being encountered; this specimen, a bird, showed great distortion of the acini and of the islets.

The study of comparative pathology of pancreatitis does not settle its etiology, but some very suggestive facts may be learned. The association of hepatic and biliary disease and of enteritis in the causation of pancreatitis seems amply confirmed, and the latter factor is in our series numerically the greater. It is suggestively shown that inflammations of the pancreas occur more frequently in the zoological class in which the ducts of the organ and of the liver empty into the duodenum together or in close association. Moreover, infections of the liver and adnexa are very important in the mammals, more so than birds in which enteritis, notably chronic in type, usually accompanied the involvement of the pancreas. This is consistent with the incidence of bile tract disease as already discussed under that subject, and it is interesting to note that the mammals showing the greatest number of cases of choledochitis and cholangitis also show the high case incidence of pancreatitis. The birds that have bile tract disease have little pancreatic disease. These facts when considered in connection with the free biliary supply of the avian duodenum, the disassociation of the ducts of the two glands and the close apposition of the pancreas to the duodenal wall, suggest strongly that direct infection of the pancreas can occur from the intestinal wall along the walls of the ducts perhaps via the lymphatics. This is supported by the observation of at least one case in which there was a definite inflammation under the adventitia of the pancreatic duct, its mucosa being normal. The study also suggests that acute pancreatitis is more often associated with acute lesions in the intestines and with hepatic or gall-bladder disease, and that chronic pancreatitis seems more often the result of chronic or repeated intestinal inflammation. Peripheral inflammation such as occurs in gastric or duodenal ulcers, has not been encountered in a distinct character so that its value cannot be estimated.

Cystic change in the pancreas has been observed a few times, but never a large visceral collection or the so-called extra-pancreatic cysts of the omentum. One acinus cyst was seen in a drake, one congenital cyst in a lark, and multiple ductal cysts were seen in a baboon and a duck. The parenchyma in all cases seemed entirely capable of functionating.

TUMORS.

Tumors of the pancreas have been three in number, two being of academic interest only. One of these concerned an apparent adenoma of the ducts within the organ, discovered microscopically in the sections from a Corsac Fox (_Canis corsac_). This is the only specimen we have had, and I can find no description of the normal microanatomy of this species, so that with a knowledge that certain carnivores have convoluted ducts, the determination is made tentatively; it corresponds microscopically to a ductal adenoma. The pancreas of a raccoon (_Procyon lotor_) showed a true adenoma of glandular acini as two separate but closely applied firm nodules surrounded by a capsule, and with distorted acini as seen under magnification. The most important tumor was found in an Indian Paradoxure (_Paradoxurus niger_), an adenocarcinoma involving the head of the organ, enlarging it to twice its normal size; there were no metastases. The animal suffered also with an infective hepatic cirrhosis of recent origin, chronic nephritis of the arteriosclerotic type, chronic fibroid splenitis. No obstruction to the biliary channels existed.

SECTION VII THE ALIMENTARY TRACT, PART 4. THE PERITONEUM

This visceral envelope is principally important because of the fatal character of its acute inflammations. In man peritonitis of acute origin and type is commonly secondary to a focus of progressive inflammation in some abdominal organ and usually speaks for the virulence of the primary disease and for the low resistance of the serous membrane. Because of this vulnerability, greater foresight is attempted to prevent the extension of acute intra-abdominal inflammations and under operative conditions punctilious care is used to avoid contamination of the general peritoneal cavity. Involvement of the peritoneum in septicemic states is relatively uncommon in man, but seemingly more frequent in the lower mammal. This surface seems more resistant to infection at operation in the lower animals since post-operative peritonitis after castration and experimental procedure is certainly infrequent; our data will permit no percentage figures of vulnerability under such conditions. Judging, however, from the number of times at which the diagnosis of acute peritonitis has been made, the lower animal has a decidedly low percentage resistance although its pathological states are primary or secondary to conditions unusual in man. Among the 5365 autopsies acute peritonitis appears in the diagnoses 137 times or 2.4 per cent.; mammals, 57 or 3 per cent.; birds, 80 or 2.3 per cent.

The exact causes are usually obvious, practically always so in human medicine, but a number of cases escape adequate explanation. From a practical standpoint two origins are important to zoological collections, trauma and intestinal perforations by sharp objects. Ungulata frequently suffer abdominal injuries in fighting, as do rodents. Peritonitis sometimes supervenes even in the absence of penetrating wounds, probably by reason of damage to the intestine whereby its permeability is increased. Pointed objects are frequently swallowed by animals and perforation occurs. The danger of feeding split bone to carnivores is well known; some years ago we lost two tigers and a lion in this manner.

Ileus, in one of the several forms, has been an occasional cause of peritonitis in primates and ungulates. The extension of purulent inflammation, abscesses and the like is easy to understand, but we have seen several cases of apparent extension from enteritis without perforation. The reason for this is probably in the kind of enteritis. Monkeys with amœbiasis and gallinaceous birds with enterohepatitis have supplied most of the cases, these infestations of the gut wall being deep and spreading so that a chance is afforded to penetrate the serosa along blood and lymph vessels. One case in a deer seemed to originate from a simple catarrhal colitis; trichocephalus in the colon may have helped. Parasites are not very potent in causing an acute peritonitis, but aggravate the action of other agents. Septicemic states are at the bottom of 24 per cent. of our cases of peritonitis. This is particularly true of birds, it being recognized that their acute general infections frequently have such an effect, but the primates and carnivores also have a vulnerable peritoneum when septicemia exists. The principal outstanding visceral lesions in the mammalian cases is pneumonia; in birds it is cholera and plague. The rupture of eggs in birds lays the foundation of a peritonitis, while bacteria from the oviduct or cloaca complete the process. Chronic peritonitis is not common. It is usually due to parasites or to tuberculosis. There has been observed, however, no complete general involvement of the peritoneal cavity including the liver and spleen, sometimes called “sugar-icing,” and believed to be tuberculous in origin. The only tumor found in very close association with the peritoneum occurred in a Chapman’s Zebra (_Equus burchelli chapmani_) in which animal a fibromyoma seemed to spring from a loop of intestine and grow away from the gut wall. It was undergoing myxoid change.

SECTION VIII THE URINARY TRACT

THE KIDNEY.

The kidneys, ureters, bladder and urethra remain comparable in all mammals excepting the monotremes where there is no urinary passage through genital openings, the urine being ejected through the vesicoanal pouch, a sort of cloaca. In the bird the first two parts remain as in mammals while the ureters terminate in a hernia-like pouch of the rear wall of the cloaca. It would seem from this arrangement that ureteral transmission of infection from the anal area to the kidneys would be facilitated in the lowest mammals and in the Aves. Variations in size, shape and position exist to a minor extent in the higher orders but in all forms, the system remains a post-peritoneal structure.

Differences in construction are to be seen for example, in the single pyramidal kidneys of marsupials and certain rodents, in the lobulated organ of bears, cattle and seals, in the twisted viscus of horses, but these gross appearances do not destroy the uniform scheme upon which the functionating unit is built. The single-lobed kidney discharges all its collecting tubules into one calyx while the multiple pyramids of the lobulated organ are fitted with individual calices which in turn empty into the pelvis proper; this is true whether the lobulations are retained, as in the bear, or are smoothed out in the course of development as in man. The secretory tubule remains in essentially the same form in all kidneys; the modern idea of its anatomy may be found in the work of Huber[32].