Part 2

It is stated in _A Handbook of the Management of Animals in Captivity in Lower Bengal_, p. 130, that elephants have been observed to shed tears abundantly if forced to leave their old home and surroundings. How much other animals who cannot express homesickness may feel it, and how often it is a cause of unhappiness, depression and predisposition to disease, it is impossible to say.

Most wild animals in captivity are sterile. The reason is not known. It shows the profound effect of captivity. It would be difficult to determine whether the sterility of a mating is the fault of the male or the female.

There is no apparent rule for sterility. Some families are always sterile in captivity, others are fertile, even with very unfavorable surroundings. The deer, horses, hippopotamuses, pigs, goats, sheep and oxen, are good breeders; while antelopes, rhinoceroses, giraffes, elephants, are poor breeders. Some members of a family may be good, others poor. The lion and puma breed fairly well; the tiger, leopard and jaguar, very poorly. Bears breed well, but the mother usually destroys her young.

We cannot mate wild animals and birds simply by putting males and females together in the same cage. Domestic mammals and birds usually mate under such conditions, but wild ones often refuse. Many mammals and probably all birds that are not polyandrous or polygamous reserve the right to select their mates, and if the sexes are put together by man they may view each other with indifference or with animosity. There are many males and females of the same species of mammals at the Zoological Garden that will not consent to live together. A male monkey in a cage with several females will very often select one female for his mate and will have nothing to do with the others.

Among monkeys fertility varies greatly. It is not practical to determine the ratio among the various kinds, as some kinds are much commoner in zoological collections than others. I think that in general the Old World monkeys (_Cercopithecidæ_) are better breeders in captivity than those of the New World (_Cebidæ_). The anthropoid apes are very poor breeders indeed; of the many gibbons, orangs, and chimpanzees, that for years have been captive in Europe and America, it is probable that only the chimpanzee has bred, and that very rarely.

Refusal to mate, sterility, infanticide by father and mother, and sexual killing keep down reproduction in zoological gardens; and the number of young ones is a good indication of the character of a garden and of the provisions made for the happiness, comfort and health of the animals.

With the birds in a zoological garden the conditions for nesting and laying are not good. Caged birds have no material for a nest, no privacy and rarely lay an egg. The outdoor water birds and the outdoor upland birds with natural surroundings, with secluded retreats, lay and hatch very well. Birds like mammals apparently are indifferent to publicity when copulating, but seek seclusion for laying and nesting—from maternal fear for the safety of the young.

The sexual instinct in indoor caged birds in a zoological garden is dormant. Very few copulate and very few lay eggs; pigeons and Mexican conures (_Conurus holochlorus_) are exceptions to this general rule.

Probably because the sexual instinct is dormant the males never fight over the females among perching birds, and very rarely kill each other. In some species of finches, however, as the chestnut-eared (_gn. Amadina_), the females fight among themselves if there are not enough males.

Ovoviviparous reptiles breed more often in captivity than one would expect; and egg-laying snakes often lay eggs, which of course are only hatched artificially.

Birds suffer less than mammals from the psychological effect of captivity. The mental development of a bird is much lower. With few exceptions, like the ruffed grouse, the bird accepts captivity easily and becomes tame, though he will not stand being touched. He views his keeper and visitors with indifference or friendliness. If a bird house is bright, cheerful and sunny, all the inmates thrive and appear to be happy. These conditions undoubtedly affect the health of the bird, as is evidenced by their plumage; bright colors that are lost in a dark and gloomy house are retained and developed when the house is cheerful and sunny. There are some birds, however, that never retain their colors in the captivity of a zoological garden. Among them are the scarlet ibis, the American flamingo, and the roseate spoonbill. It has been suggested that the loss of color is due to the lack of something in the diet, mineral or organic, that the bird gets in its natural habitat. Tame scarlet ibises living with the chickens about the dwellings of natives in Venezuela retain their brilliant color. The material of the beautiful red color on the under surface of the wings of the touracou contains copper, yet these birds retain this color very well in captivity, even after several moultings.

The source of the copper has long been uncertain. In nature the birds are fruiteaters, and their diet in captivity consists of bone meal, zweibach, corn meal, white potatoes, eggs and carrots—foods that are usually assumed to contain no copper; and no copper utensils are used in the preparation of the food. Dr. John Marshall, however, writes me that all the common cereals contain minute quantities of copper; and Dr. Leon A. Ryan, _University of Pennsylvania Medical Bulletin_, June, 1907, states that copper may be found in animal tissues. Dr. E. P. Corson- White has found traces of copper in the bone meal used at the Philadelphia Zoological Garden. The copper in the red color of the touracou’s wing therefore comes from the food.

It is probable that a bright and cheerful bird house does not influence the color of birds by the direct action of light on the color as much as indirectly by improving the health and spirits of the birds. Coloration in birds is a very complicated proposition. It depends upon age, sex, season, health, light, heat, moisture, mode of life, and food. No one bird house can combine all the conditions necessary for the retention of natural colors in every species. The desert species from a habitat of intense light and dryness require for their color a different environment from the forest species, from a habitat of shade and moisture. The suppression of sexual feeling in captive birds may influence color. In nature the finest colors are attained by mating birds.

It may be said that all animals—except those of nocturnal habit—have a feeling of joy and well-being in fine weather and bright surroundings that reacts favorably on the general health.

The variability of the breeding period induced by captivity in many animals may be mentioned with sterility. It was shown some years ago in the Philadelphia Garden by the European brown bear which in one year gave birth on January 16th, and in the following year on July 25th. It is another evidence of the profound effect of captivity on the captive animal. I know of no observations of the effect of captivity on the period of gestation.

There is considerable mortality among captive animals from killing of cage-mates. I do not refer to sexual killing, already mentioned, or to fights over a female. Often males, with no females near, cannot be kept together; probably sexual jealousy is at the bottom of it. Antelope and deer are especially inclined to scrap. Even a large enclosure will not save the weaker male; the stronger follows him with horrible persistency, sometimes for days, around and around the enclosure, often at a walk, but always on the offensive, at least during the day; until, careless from weariness, the weaker is caught unawares and finished by a horn-thrust in the side.

Both birds and mammals often kill their mates when the mate is sick, or “down” from injury or disease. All animals hate sickness and death, and show their dislike by attacking or shunning it. Birds may get on happily together for months until one becomes sick, and as he crouches in a corner with ruffled feathers the others pick on him and finish him. The same is true of mammals, the sick one being horned or tramped to death by the mate with whom he had formerly been on most friendly terms. The keeper often reports an animal “killed by its mate,” whereas the mate has only given the _coup de grace_.

This brutality is not universal. Rarely a parrakeet will stand guard over his sick and dying mate; and we have seen a ratel—of a ferocious family—stand guard over and resist the removal of his sick companion.

The diagnosis of disease in wild animals is unsatisfactory; usually impossible; clinical study as we know it in the human is impossible. We know that the animal is sick, but not why. A certain group of symptoms accompanies all diseases—dull, rough coat or feathers, refusal to eat, weakness in the hind quarters, and finally getting down. They rarely show symptoms of pain—or at least we cannot read the symptoms. The pain of acute pancreatitis in man is violent, yet many animals die with it and we cannot tell that they suffer. Animals do not suffer as much as the human, and they stand the ravages of disease better than the human. At autopsy we often wonder how the animal could have lived with the conditions that are found. A monkey may be apparently well until a few days before his death, though his lungs and abdominal organs may be a mass of tubercle. A small red howler monkey (_Alonata seniculus_) was in apparent good health, playful and lively until twenty-four hours before his death from acute pancreatitis, though his stomach and intestines contained fifty-one nematode worms, some of which were eight inches in length.

As diagnosis is unsatisfactory, so is treatment. Usually all we can do is to treat symptoms; and by the time disease has advanced to the point of becoming externally noticeable, it has usually gone beyond the reach of medical treatment. It must also be remembered that drugs vary very much in their action in different families of animals. Nux vomica will not kill the gallinaceous birds of North America, and Tenant says that in Ceylon the hornbill feeds on the fruit of strychnos nux vomica. The pigeon is immune to opium. The _Felidæ_ are said to be unusually susceptible to carbolic acid; veratrum viride is harmless to sheep and elk, but poisonous to the horse; dogs can take with impunity large quantities of cyanide of potassium. These statements are true when the drugs are administered by mouth—the usual way of giving them to wild animals. The action may be different if the drugs are administered intravenously or subcutaneously. Variations in effect when they are administered by mouth are often due to chemical variations in the digestive secretions. It is probable that the action of cyanide of potash on dogs depends on the amount of hydrochloric acid in the digestive tract.

When worms or their eggs are found in the stools vermifuges are used, and with some animals especially liable to infestation by intestinal worms, periodic doses of vermifuges are given as a prophylactic. Turpentine is given to the zebra at fixed intervals for the round worm; santonin, male fern and areca nut to the carnivora for the various worms that are so common in the intestinal tracts of these animals.

The work of the Laboratory of Pathology is throwing light on the subject of diagnosis, and though from the character of the clinical material diagnosis can never be as satisfactory as in the human, yet we may fairly hope for improvement. Prophylaxis is our chief reliance, and always will be.

DISEASE IN CAPTIVE WILD MAMMALS AND BIRDS

SECTION I INTRODUCTION

“We have also parks and enclosures of all sorts, of beasts and birds; which we use not only for view and rareness, but likewise for dissections and trials, that thereby we may take light what may be wrought upon the body of man.”

The purpose of a menagerie under the auspices of a zoological society can scarcely be put into better words than those found in this quotation from Sir Francis Bacon’s _New Atlantis_. Apt as this description of the mythical island’s collection may be, it is but a reflection of the teachings of Plato’s original legend of a perfected community, and the practical applications of these teachings by Aristotle in his _Anatomy and Physiology of Animals_. The history of human study shows a constant investigation of lower forms of life, ever broadening in its scope, ever more satisfying in its explanation of biologic problems and ever increasing in value from an economic standpoint.

If, however, all animals are to be subjected to “dissections and trials” there inevitably will come under observation many specimens presenting variations from the accepted mean or standard or even from an average for their kind and therefore approaching what may be called pathological.

The desire to explain the abnormal has had the effect, during the half century since Virchow defined cellular pathology and Darwin systematized the world’s knowledge of comparative biology, of directing attention to comparative pathology and of stimulating the study of veterinary medicine. Moreover in the past twenty-five years much work has been done and many isolated publications have appeared upon the diseases of wild animals, notably Bland-Sutton’s work, _Evolution and Disease_ (1895), a thoroughly scientific and most charmingly written book, but rather elementary in its approach of the subject of pathology, and Wood Hutchinson’s _Diseases of Animals_, a more or less popularly presented treatise. I am unaware, however, of any systematic monograph upon the subject wherein we may find data showing the character of pathology in the various animal groups or the incidence of the various lesions. The reports of some zoological gardens contain the result of medical and pathological data collected for the report period. The publication of greatest merit and value is that from the Zoological Society of London, whose huge collection studied by a large official personnel makes it possible to present valuable data. The New York Zoological Park uses its material in a similar manner and has been able to explain some of the knotty problems so frequently met in wild animal collections.

Here at Philadelphia it has been our practice now for twenty years to perform an autopsy upon every mammal and bird that dies, and upon all of the large or important reptiles. There is no aquarium connected with the Garden. The office of the society keeps a record of the arrival and a general description of every animal so that a brief history of the specimen is usually available. The keepers are required to observe their charges regularly and closely and to report any abnormalities to the officials of the Garden. Somewhat detailed discussions upon signs of sickness will be given at appropriate places, where also a few remarks upon treatment will be included, but as this work is not intended to be a treatise on therapy and since this subject does not differ from that referable to domesticated animals, little space will be devoted thereto. Upon death a complete autopsy is performed and the findings are recorded upon a printed form from which, when the histological, bacteriological and parasitological studies have been completed, a set of cross index catalogue cards are typed; these are divided into the principal diagnoses and determinations. The report of the Zoological Society, appearing at the end of their fiscal year, February 28th, contains a résumé of the observations for the year, together with notes of interesting cases and experimental work.

There have accumulated the records of nearly six thousand autopsies and upon them as a basis has been founded the following report of the incidence and nature of pathological manifestations in the various animal groups, using also as additional data, published reports from other gardens. The book might be described as a collection of our studies, parts of which have appeared as separate articles, but most of which are entirely new, put together with as much connection as the subject matter will permit. The zoological and pathological literature has been consulted very extensively, but except for the reports of zoological societies and the publications of special students, it usually represents isolated notes by travellers and veterinarians so that many articles may have been overlooked. Therefore no claim of perfect completeness of reference is made, the statements resting chiefly upon our own records. The subject will be approached from the standpoint of description and incidence, but it is inevitable that comparisons and contrasts must be noted.

Into the realm of evolution[1] I shall not venture because I appreciate a lack of adequate preparation for such an attempt, and because, even if such were not the case, the material at hand is lacking in data upon fishes, many kinds of reptiles and invertebrates.

A direct and practicable application of these data will be in the direction of explaining some of the pathological states in domestic animals and man. There are indeed many disease entities or syndromes in these groups for which no useful hypothesis has been advanced, while for others a partial explanation has been offered, usually, however, inadequate wherewith to form the basis of rational prevention or therapy. Thus, for example, essential emphysema seems to be limited to the animals of civilization; on the other hand, the anatomical basis of exophthalmic goitre may be seen throughout nearly the whole animal kingdom yet the clinical phenomena belong characteristically to man, and are occasionally seen atypically in the dog. While it may be impossible to give a complete comparative anatomy and physiology for each of the pathological states, the attempt will be made to treat all subjects analogically through the zoological orders.

The experimental pathologist may find the records of the Garden useful in his work. For example, he can know that rodents are not prominent among the orders showing spontaneous arteriosclerosis, but that nephritis occurs among them in about a quarter of natural deaths; or he may learn that the Primates have a good cardiac reserve while the Marsupialia have not. Too often experimental work is not based upon facts including natural probabilities.

A collection of pathological data such as is presented in the following pages may be of assistance to veterinarians and managers of zoological gardens in the diagnosis of sickness in animals, both wild and domesticated. We do not presume to offer a system of veterinary medicine, but it is possible to introduce certain objective findings of practical hygienic and therapeutic value. Such observations are, however, limited and in our experience at the Philadelphia Garden the diagnosis of disease in a wild animal, excepting of course those which are perfectly self-evident, is more often speculation and conjecture than at all well grounded. It is not uncommon for animals to come to autopsy presenting a perfect galaxy of abnormalities, yet the closest antemortem observation failed to reveal unusual conduct or appearance. On the other hand specimens are frequently opened whose organs fail to contain any lesions discoverable even by careful study. Dr. Henry Chapman, sometime prosector to the Society, once made a remark in this connection—“Why do they die or how can they live so long.” Space is given to this phase of the observation of wild animals in order to emphasize the difficulties of interpreting their conditions, but of course it should be understood that certain data of value may be gained by close attention to the details of their normal behavior and to changes which occur indicating that something is wrong.

The naturalist and the trained animal keeper are, in our opinion, better judges of a wild animal’s condition than is the veterinarian, unless he be at the same time a zoologist and have long experience with a menagerie. My own observation of dogs and horses leads me to think that more acumen is needed to interpret the actions of wild animals since they seem to have greater natural reserve, and of course in regard to them there are many more variables since we see fewer specimens of each species than we know familiarly among domestic varieties. The principal objects for observation are, as in veterinary medicine, the eyes, the hair and skin, the mucous surfaces, the droppings, the condition of the abdomen, the appetite and the desire for water. Physical examination is limited to tractable beasts and those which can be caught and handled without danger to the personnel or unusual fright and damage to themselves. In the interpretations of physical signs in tractable animals, such as many ungulates and some monkeys, the experience of the trained veterinarian is of the greatest value, but this fails amongst carnivores and birds. It might be said that anesthetics could be used for a thorough examination, but this would be undesirable for a seriously sick animal and it is, in our experience, none too safe a procedure although often perfectly practicable. Animals do not like to be molested much as they may seem to enjoy attention, and when it is possible it is our practice to avoid handling them.

It might be contended that observations upon diseased states in captive animals would not represent natural developments, in other words, not that which occurs in the wild. Such indeed may be true in regard to the infectious diseases, but since we are imperfectly informed as to the pathology of the wild state, we are obliged to accept and use the best substitute at hand. Moreover it seems perfectly fair to consider as characteristic for an animal or group, the physical and even physiological expressions of morbid agencies as we know them, even though the animals be at the time under conditions not natural to them. It would be perhaps incorrect to say that cirrhosis of the liver occurs in .6 per cent. of animals in the wild as is the case for our autopsies, since incorrect food and infections are potent in its causation; on the other hand, our experience and some few data from naturalists and pathologists make it conceivable that tumors occur to this number in native states. The incidence of tumors in wild rodents is quite well known. Degenerations and fibroses, the result of parasitism, are known to exist throughout the entire animal kingdom. Further to illustrate how pathology is distributed in wild life, Plimmer’s experience[2] with 500 rats (_M. decumanus_) might be cited. He found the following: Tubercle 3 times, tape worm cysts 10, Tryp. lewisi 49, empyema 2, tumor of jaw from old injury 1, pleuritis and hydrothorax 1. Bacteria were found in 71 rats, 40 times in the lungs, 31 times in the spleen; saccharomyces were found 16 times in the lungs. Dr. W. L. Abbott reports to us personally that he has repeatedly found coiled exproventricular worms in the wild specimens he has collected. Not only are we informed of some isolated and individual pathological states but the existence of epizoötics of communicable disease among wild life is well authenticated. The simple citation of the extermination of deer in one section of Colorado by pleuropneumonia will suffice to illustrate this point. Other examples are, however, interesting. The occurrence of changes in the jaw bone almost certainly those of actinomycosis is reported by Blair, the specimens being shot in the wild and believed never to have been near civilization. The white-tailed deer of the Swan River Valley in Montana, are known to be constant carriers of liver-flukes.