Part 14

It is customary to divide the descriptions of normal and diseased conditions of the upper entrance to the body into respiratory and alimentary parts, the nose, nasopharynx and larynx belonging to the former, the mouth, buccal cavity and pharynx to the latter. As a matter of fact they can for most purposes be considered as the structures contained in the anterior head and furthermore their pathological states are more often followed by extensions into or implications of the respiratory organs proper than of the alimentary tract. From a comparative standpoint the incidence of specific infectious diseases and of the involvement of accessory nasal sinuses present the most interesting subjects. There are several infections, believed to be specific, observed among domestic mammals and birds but their actual individuality has hardly been unexceptionally proved. This refers to the communicable rhinitis of cows, pigs, rabbits, and birds, especially parrots, the follicular catarrh of horses, and croupous nasopharyngitis, all of which have been ascribed to a particular virus, without finished evidence in many instances. Some of these diagnoses doubtless cover or are confused with the early symptoms and signs of the disease of protean manifestations, distemper, and indeed the Bact. septicus and relatives of the bird cholera organisms are reported as being responsible for them. No intention of excluding well recognized entities like bird diphtheria, foot-and-mouth disease or influenza, exists. I shall refer below to small groups of epizoötics which do not conform strictly with word pictures drawn by Hutyra and Marek, Moore, or Ward and Gallagher.

RHINITIS, SINUSITIS.

The nature of inflammations of the nasopharynx suggests at once that there may be some anatomical reason for their distribution and character. A general review of the anatomy of the mammalian and avian nasopharynx reveals the relatively greater space in the former, especially in the passage from the nose to the pharynx, and emphasizes the exposure of the opening of the upper larynx in the bird, lying as it does in the posterior part of the tongue and surrounded by the constrictores glottidis. A dissection of the accessory nasal sinuses exposes the relatively large size of these spaces in the lower mammals, and the capacious openings into the nasal cavities.[20] In the Primates and Lemures the anatomy more closely resembles that of man, the sinuses being relatively smaller and the communicating passages narrower. In the bird on the other hand, while the sinuses may be extensive in some they are usually small, yet in all the communication with the turbinate area is by a narrower slit or tortuous canal, frequently, as in Galli, running from below upward into the maxillary sinuses. The extent of the turbinate and the richness in mucosa is probably greater in all mammals than in birds; certainly this seems true of Carnivora and Ungulata _versus_ Accipitres and Galli.

If the seriousness of a rhinitis be dependent upon the extent of involvement of the sinuses and the blocking up of their outlets it would be expected that the variety of animal having the smallest drainage channels would show the greatest evidence of these diseases. Our records would indicate that 32 birds (.96 per cent. of the autopsies upon Aves) had rhinitis whereas only 7 mammals (.39 per cent. of autopsies on this class) presented the condition. Extension to the sinuses occurred in only one-third of each of these figures, a complication which in turn produced generalized infection more often in mammals than in birds as 4 is to 3. These figures are perhaps too small for conclusions but it would seem that rhinitis occurs more often in birds with their small sinuses and channels while sinusitis and general infection occur more often in mammals with their large sinuses and extensive turbinate apparatus. The most conspicuous orders represented are, in line of numbers Anseres 12, Psittaci 7, Accipitres 5, Carnivora 3. Nine of the twelve waterfowl were part of an epizoötic which will be discussed under specific diseases.

Bacteriologically the mammalian cases that have been worked out were due to _Streptococcus pyogenes_ in several instances, including the generalized cases, and to a mixture of streptococci, golden staphylococci and members of the colon-aerogenes group. In one case in a tapir a member of the B. septicus group was found. Moulds were discovered in three avian cases and filaria in one. No pentastomum or œstrus has been discovered. In thirteen instances the lungs have been involved, apparently secondary to the nasopharyngeal disease.

There have been two small outbreaks of an acute nonspecific infection— that is not suggestive of cholera, psittacosis or infectious enteritis— among the parrots in which during a short time 4 and 6 parrots died with nasopharyngosinusitis as the prominent lesion. One outbreak was studied bacteriologically without definite result. There was no uniform internal pathology unless, in one outbreak, congestion of the cerebellum may be mentioned. Fowl diphtheria and its associated condition from which a satisfactory separation has not been accomplished, epithelioma contagiosum, has happily given us little concern, so that it is not possible to record any instructive facts upon its cause or differential diagnosis. There was recorded in the 1911 Report of the Society the occurrence of two fatal cases in cassowaries from which it was possible to isolate the B. columbarum and one bird with the same clinical appearances whose recovery seemed to be due to the use of human diphtheria antitoxin. In light of more information and consideration of the accepted variability of this disease, it is possible that this bird may have recovered without the injections or with the use of normal serum. Nowadays it is possible to obtain antiroup serum which is stated by Blair of New York to be efficacious. The disease has been observed in a wild turkey and an Abyssinian Ground Hornbill, beside the two struthious birds mentioned above.

MYCOSIS.

Mycotic disease of the nasopharynx seldom restricts itself to this cavity, usually extending by continuity to the esophagus, or by inspiration to the lungs whence it spreads to the air sacs. This condition of the upper passages has occurred here only in Psittaci and Accipitres although it is reported by veterinarians as occurring in Anseres and Struthiones. In the first order four birds were affected, two showing extension to the esophagus and a like number having pulmonary and serous membrane involvement. These cases were all due to aspergillus whereas those next to be mentioned were caused by an oidium close to the “albicans” variety. In four Mississippi kites the prominent changes were found in the pharynx and esophagus down as far as the proventricle with only a few rather trifling lesions in the nasal area. Infiltrative and necrotizing processes characterized the action of the oidium while that exerted by the aspergillus was more superficial and extensive. In one case of a parrot the whole nasal cavity was completely filled with a yellow gray exudate whereas the esophageal wall of the kites was thoroughly infiltrated by a gray-brown, friable, necrotic mass. Attempts at treatment were made in the case of the latter, using potassium chlorate and saline solution on cotton swabs. The result was entirely negative and the applications seemed to have no effect upon the course of the infection.

There are on our records in addition to the above, several cases of necrotizing processes about the head seeming to emanate from wounds to the mucosa by foreign bodies, by decomposition of pieces of food in crevices or by damage by masses too large to be swallowed. In the few instances where we have tried bacteriology, no definite result has been obtained unless the frequent occurrence of organisms bearing a resemblance to Bact. necrophorus be important. This organism however may be found in many necrotic processes in animals; I do not look upon it as specific in the locations just cited.

Mammals as a class do not present many inflammatory conditions around the anterior head, aside from the specific diseases like distemper (?), actinomycosis, Kangaroo disease and the like. Monkeys occasionally have acute coryza, which may indeed seem transmissible to others but it seldom leads to any serious consequences and is untreated, except by segregation. Tuberculous lesions are not recorded. There has been no glossitis aside from lesions involving the pharynx. The tonsils have been discussed under the lymphatic apparatus and it only need be repeated here that inflammation and hypertrophy of these organs are exceedingly rare. Specific or individual diseases of the salivary glands are also rare although these organs may be involved by extension. This general region is not often affected with tumor, unless the jaw be included which bone is the seat of several tumors in antelopes and opossums. Aside from these we have seen an epithelioma of the tongue in a black bear (_Ursus americanus_).

LARYNX.

The larynx is an organ of fairly uniform construction through the mammalian orders but is conspicuously different in the Aves where it is double. The upper end of the trachea in the latter class is surmounted by a cartilaginous box lying beneath the root of the tongue through which an anteroposterior slit-like opening forms the glottis; there is no epiglottis. This is only an air passage, the voice being made in the syrinx or lower box which lies at the bifurcation of the trachea. The structure of the upper box is quite simple with its lateral plates controlled by the glossal muscles and two external retractors but the syrinx is very complicated and variable in the different orders and even in the same family. It possesses an internal and external set of muscles and in some birds can be opened at one point to permit air to pass to the cervical or thoracic air sacs. Detailed discussion of its anatomy is hardly profitable since there is nothing peculiar about its diseases. On one occasion only have we seen distinct pathological change—what was probably an extension of mould disease from it to the cervical air sac. It is involved in true tracheitis and bronchitis but even these are rare in birds.

The larynx on the other hand is constantly reddened in cases of pharyngitis and may be the seat of mould colonies. Edema of this structure is, however, not very common, it being recorded but twice in birds in association with nearby inflammation and five times in mammals; in the latter cases three were of acute infectious nature, one was a tumor and the other osteomalacia. It is common to find the laryngeal and tracheal mucosa swollen and wet in chronic bone degenerations without the condition being severe enough to call it edema.

LARYNGITIS.

Acute laryngitis of active catarrhal or purulent nature has been met five times in mammals and twice in birds while more chronic lesions have occurred only in the former, four times. Tuberculous laryngitis has been observed in a cockatoo and a lemur; they are interesting enough to cite. There are no cases recorded among monkeys despite the large number dying from the disease; this implies of course that no suspicion of its existence was had at postmortem but perhaps some would have been detected had every larynx been subjected to microscopic section. A citron-crested cockatoo was found when posted to have general miliary tuberculosis. The bright red rim of the glottis attracted attention and upon slitting open the organ, pinhead size, sharply outlined yellow tubercles were found on both sides. A black and white lemur was killed because of a positive tuberculin test. He was in good condition and exhibited as his only lesions retropharyngeal lymph nodes with precaseous miliary nodules and small miliary tubercles on the epiglottis, true and false vocal chords and in the mucosa of the main ventricle, each lesion being surrounded by a narrow sharply injected zone. This seems like a recent double implantation since the retropharyngeal glands probably do not drain toward or from the larynx. The larynx has been the seat of only one tumor, a squamous cell cancer in an Azara’s agouti. The tumor caused ulceration and edema of the whole mucosa sufficient to produce fatal asphyxia.

The trachea is of relatively little comparative or pathological interest aside from its inflammations which however are so closely associated with bronchitis that they will be included under that heading. Perhaps the most important condition of this tube is its infestation with _Syngamus trachealis_ since this leads to inflammations not only of the related mucosa but predisposes to pulmonary infection. The occurrence in the Galli is well known but perhaps it is not so well recognized that this worm occurs also in crows (Passeres) and swans and geese (Anseres). For the diagnosis of this condition it is customarily stated that a frothy mucus in the mouth is very suggestive; this is true in the cases seen here but in addition a mucopurulent stomatitis is exceedingly common and when the two are combined the picture is almost confirmatory. Although worms are credited with considerable weight in the production of pneumonia in Ungulata, they have only been seen once within the tracheal tube.

THE BRONCHI.

The bronchi will be discussed as a separate part of the respiratory system in so far as possible since they present a very decided difference in anatomy between mammals and birds and because the incidence of their disease is other than will be found for the lungs. However, distinction has been made between changes in the grosser tubes and those in the finer bronchioles, especially because capillary bronchitis so-called is really a pneumonitis in which the mucosa of the larger passages need not participate. The mammalian tubes are not really greatly different in their construction, passing through ever smaller branchings which give an increasing square area of tube capacity and more extensive mucous surface. The avian main bronchus breaks up very shortly after entering the lung into a varying number of spaces lined with low epithelium lying upon a fibrous support and without cartilage. These spaces then open into secondary air spaces of a size visible to the naked eye which are in turn surrounded by microscopic alveoli. The largest spaces, first mentioned, continue to grow smaller toward the lower part of the lung where they usually communicate with one or other of the various ostia of air sacs. Bronchial diseases in birds must therefore be limited at the place where the bronchi lose the cartilaginous rings since below this the surface functionates as pulmonary tissue.

BRONCHITIS.

The accompanying list, Table 8, will show the distribution of bronchitis not accompanying pneumonia or due to mycosis. It is striking that carnivorous animals are more prone to bronchitis than any other order (the struthious birds are too few to be important). There is a very decided preponderance of mammalian cases over avian, there being not only more cases but proportionately more orders affected. The character of lesions in the mammals is nearly always catarrhopurulent or freely purulent while ulcerative changes are not uncommon. Peribronchial infiltrates are seldom found without some evidence of pneumonia; nor is it common to meet the pale lines extending from bronchi between the lobules, such as are seen in human streptococcal disease. Avian bronchitis is usually hemorrhagic or catarrhal and with exceeding rarity becoming purulent; when this occurs the cause is frequently found to be tuberculosis or mycosis. Inflammation of the larger passages is nearly always accompanied by pulmonary congestion, a serious condition in birds as will be seen later. A few of these cases have been studied bacteriologically with no definite result, nor have these cases occurred in such groups that an epizoötic was suggested. Bact. avisepticum, Bact. canisepticum, Bact. coli, Bact. aerogenes mucosum, and Ps. pyocyaneus, Streptococcus hemolyticus and non-hemolyticus and staphylococci have been found.

TABLE 8. _Showing the Percentage Incidence of Bronchitis and of Parasites in the Autopsies upon the Various Orders._ ════════════╤═══════════════════╤═══════════════════╤═══════════════════ Orders │ Simple Bronchitis │ Verminous │Inactive Parasites │ │ Bronchitis and │of Lung (Encysted) │ │ Pneumonitis │ &c. ────────────┼─────────┬─────────┼─────────┬─────────┼─────────┬───────── „ │ Cases │Per cent.│ Cases │Per cent.│ Cases │Per cent. ────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼───────── Primates │ 7│ 1.4│ 3│ .6│ 5│ 1. Lemures │ │ │ │ │ 1│ 1.2 Carnivora │ 14│ 2.9│ 8│ 1.6│ 8│ 1.6 Insectivora │ │ │ │ │ │ Chiroptera │ │ │ │ │ │ Rodentia │ │ │ 2│ 1.│ │ Ungulata │ 5│ 1.3│ 2│ .5│ 10│ 2.7 Proboscidea │ │ │ │ │ │ Hyracoidea │ │ │ │ │ │ Edentata │ │ │ │ │ 2│ _12.5_ Marsupialia │ 3│ 1.7│ 2│ 1.1│ 3│ 1.7 Monotremata │ │ │ │ │ │ │ │ │ │ │ │ Passeres │ 4│ .29│ 7│ .5│ 2│ .16 Picariæ │ │ │ │ │ │ Striges │ │ │ │ │ │ Psittaci │ 4│ .58│ │ │ │ Accipitres │ 1│ .5│ │ │ │ Columbæ │ │ │ │ │ │ Galli │ │ │ 1│ .3│ │ Hemipodii │ │ │ │ │ │ Fulicariæ │ │ │ │ │ │ Alectorides │ │ │ │ │ │ Limicolæ │ │ │ │ │ │ Gaviæ │ │ │ │ │ │ Impennes │ │ │ │ │ │ Steganopodes│ │ │ │ │ │ Herodiones │ 1│ 1.│ │ │ 1│ 1. Odontoglossæ│ │ │ │ │ │ Palamedes │ │ │ │ │ │ Anseres │ 2│ .67│ 3│ 1.│ │ Struthiones │ 1│ _3.3_│ │ │ │ ────────────┴─────────┴─────────┴─────────┴─────────┴─────────┴───────── For meaning of italics see footnote Table 1.

A review of the active verminous lesions of the bronchi and the pneumonitis to which parasites lead, shows again the highest number among the Carnivora, with negligible percentages among the Aves. The forms concerned are, when determined, ascarides, strongylus, hepaticola, fasciolopsis, cytoleichus, pneumonyssus and paragonimus; these will be discussed later. The lesions in the bronchi are mucocatarrhal or hypertrophic; occasionally actual ulcerations are seen. What is more important however is the peribronchitis leading to interstitial pneumonitis and to bronchiectasis of the smaller bronchi, or to areas of atelectasis by total occlusion of some small air passage. This pathology is fairly well recognized among veterinary pathologists but there are two points which seem worthy of special emphasis, namely, the relative mildness of the changes in the larger bronchi and the importance of the worms as causes of pneumonia. In regard to the first it can be pointed out that the trachea and its branches need not be altered at all while the middle sized bronchi present a mottling of small recent congestion with pigmentations from old hemorrhages, together with slight unevennesses of the surface. Small bronchi on the other hand are the seat of ulcerative internal processes and quite marked peribronchitis, as indicated by round and connected tissue nuclei or perhaps polynuclear increase under active acute inflammation; it is in the latter case that acute pneumonitis is present.

To what extent do the parasites predispose to pneumonia? Compare for this purpose the two columns of Table 8 showing active and inactive pulmonary parasitism. In Rodentia and Galli alone do we note that active parasitism is effective, there being no passive cases. In all the other orders, animal invaders of the lung are more often encountered as quiescent or encapsulated bodies, therefore as findings incidental to the autopsy and perhaps not concerned in the cause of death. In Ungulata the inactive parasitisms are five times as frequent as the active inflammatory lesions. It might be added that the list is made up of cases wherein we saw parasites whether determined or not, an explanation of the apparently small number of cases; there were many more in which such invaders were suspected but not found and therefore excluded.

BRONCHIECTASIS.

Bronchiectasis affecting the smallest tubes, or bronchiolectasis, is not at all uncommon in verminous pneumonitis and is explained as due to the degeneration of the wall, the surrounding progressive ulceration, to accumulation of inspired air and its retention by the obstruction. There is described a generalized bronchiolectasis, chiefly in young human beings, due to a destructive bronchiolitis; this has not been seen.

Non-verminous bronchiectasis of the middle sized bronchi such as is seen in human chronic bronchitis, simple or tuberculous, is quite uncommon. Widening of the bronchial lumen may be divided, as I see its pathogenesis, into (a) that due to congenital weakness of the walls, (b) that due to obstruction permitting air to pass into but not out of a bronchus because of a ball-valve obstruction or weakness of expiratory power, (c) that due to external pressure by tumors or distortion by fibrous tissue either within the lung or pleura and (d) that due to inflammatory weakening of walls, augmented by loss of supporting pulmonary tension, accummulation of secretion and the dilating effect of inspiration preparatory to and incidental to coughing. How important the last three auxiliary factors may be in the cases explicable under a, b, c, can easily be speculated upon and may vary in different cases.