SECTION XIV. Constitutional Diseases

CONSTITUTIONAL DISEASES

There is a long list of diseases including among others such conditions as hyperthyroidism, osteodystrophies, diabetes and gout which are spoken of as constitutional but which in reality are usually dependent upon some lesion peculiar to a definite organ. Several have been discussed under systemic diseases so that there remain for consideration in this section only two, gout and diabetes.

Constitutional diseases are recognized in wild animals either not at all or by some happy chance which permits of examination direct enough to elicit diagnostic criteria. Gout has been discovered for example in some parrots and herons because of their swollen feet and their movements. In veterinary practice fairly accurate diagnoses are possible but in wild collections they are nearly always hit or miss. Therapeutics naturally follow this rule.

GOUT.

Gout in mammals has been observed in the London Zoological Garden but has not been encountered here or we have overlooked it. Avian gout on the other hand in one of its forms comes to our attention not infrequently. It occurs most often in parrots, gallinaceous and anserine birds and herons; occasionally accipitrine birds will suffer with it, an observation more often recorded in European collections than with us. The figures show no predominance of percentage for any order but the records indicate that the most beautiful examples of internal uratic deposits occur in the anserine birds and parrots, while the best specimen of general gout, including the joints, was found in a boat- billed heron (Cancroma cochlearia) quoted below.

In so far as etiology of this disease is concerned in domestic stock, too rich food, especially in protein, and restriction of activity seem to be credited with the greatest influence. These factors, while doubtless of importance for birds as they are believed to be for man, do not seem to fill all the requirements since all our specimens are confined and, because of their lack of exercise, possibly receive too much food. Judging by our observations and by publications from other gardens, carnivorous birds are not conspicuous for the incidence of gout whereas grain- seed- and fish-eaters suffer more often. This suggests that these varieties cannot dispose of dietary protein which might be excessive for their metabolism while in captivity, whereas carnivorous species have a digestive and chemical reserve to take care of excess protein. Some such accommodative power must exist in human beings since not every large meat-eater develops gout. Heredity, often blamed for the human disease cannot help us with these birds. Examination of the diet list at the Garden does not reveal a great percentage of concentrated protein in the feed of the grain- and seed-eaters. The disease occurs too seldom to disturb the accepted dietary for its possible elimination. Studies now going on may indicate appropriate changes in the dietaries that might be responsible.

Arthritic gout appears usually in the pedal joints but may be found in the wings. Irregular, sometimes very deforming swellings appear which must be tender judging by the quietness of the bird and by its behavior if the joints be touched. Most often the swelling seems greater upon the flexor (palmar) surfaces of the toes or in the end of the tarsal articulation. Aside from these few observations there is nothing peculiar about the attack or the specimen during its sickness. Chronicity seems to be the rule and little emaciation may be found. Appetite is normal or excessive, provided the food can be reached.

Internal or serous membrane gout cannot be recognized during life so far as I know. The bird may seem in its usual condition of feather, activity, appetite and elimination, when suddenly it will fade in a day or so and die. At autopsy the serous surfaces of the heart and peritoneum will be white with uric acid crystals and the kidneys a pale yellow brown with markings indicating that the pelves and tubules are choked with urates.

The boat-billed heron (Cancroma cochlearia) had had bad feet for three months. The general condition is poor as to plumage and flesh. The tarsal and metatarsal joint areas of both legs are surrounded by firm tough swellings involving skin and periarticular tissue. That on left foot has ulcerated and bled. On section the swelling is found to consist of reddened fibrous tissue around tendons, the latter apparently running through smooth sheaths. At both ankles are urate deposits clearly seen in this inflammatory tissue but at the lower end of the tarsus there are no distinct deposits. The joint surfaces do not seem to be involved. Knee, hip, and wing joints seem uninvolved. Internally all surfaces are opaque by sprinkling of whitish or yellowish dots like urates; this is especially marked over heart. Pleuræ aside from urates are negative. Lungs very slightly uniformly congested throughout. Aorta and branches are stiff, intima smooth. The liver is soft, deep brown color, architecture seems normal. The kidney has a smooth capsule and a smooth pale yellow surface. Organ is firm. Section surface is glistening and opaque, every lobule clear, pelves filled with pale yellow material, cortical areas irregular. Alimentary tract negative. Microscopical section of kidney shows general topography retained, vessels very much injected, some showing thrombosis. Cortex slightly irregular probably by swelling of medulla. Tubular epithelium swollen and granular or desquamating and degenerating. Glomeruli vary in size and shape, mostly fill out the capsule. Capillary cells show some vacuoles. Some urate collections in tubules; practically all pelvic tubules have some urates. Interstitial tissue not increased. Blood vessel walls somewhat loose. Endothelium prominent. No areas of degeneration seen.

DIABETES.

Diabetes is an infrequent but well recognized disease among domestic animals. Its detection depends on a rather vague chain of symptoms confirmed by the discovery of sugar in the urine. For the suspicion that a wild animal was suffering with diabetes one would have to rely upon great thirst, loss of flesh, depression, excessive urination and possibly cataractous opacity of the eye. Such a chain of symptoms has not been detected. At every occasion at postmortem that the bladder is full of urine, a routine examination is made. In this way we detected one case which seems to have been diabetes, the diagnosis being based upon the glucosuria and the lipemia. For some unknown reason a section of the pancreas was not made, a regrettable matter since a definite purulent gingivitis existed and may have lain at the basis of an infective pancreatitis, well known to be the cause of certain cases of diabetes. The case is recorded in full since it is unique, no other case in a wild animal being fully reported.

The arctic fox (Canis lagopus) ate and appeared well the day before it was found dead. Diagnosis—Diabetes mellitus. The animal was in good condition. The left conjunctiva was reddened, congested, edematous, with slight mucopurulent discharge in canthus. Muscles have a cloudy appearance. Fat lacks rich yellow color. The general impression of anemia is present. Lungs and pleura are normal throughout. Heart muscle is pale, firm and tough. The tricuspid shows thickening of the edge of posterior leaflet, the mitral shows slight sclerosis of edge of mesial leaflet. The auricles are distended with clot. Left ventricular wall is greatly thickened. Upon incising the heart the surface of blood shows fine fat globules. Peritoneum is normal. Liver is slightly increased, surface smooth, edges rounded, consistency soft, color brownish red with yellow mottlings which are without definite boundaries; the section surface is moist, granular and opaque. The bile is fluid, green-yellow and the duct is patulous. The spleen is slightly enlarged and soft. The kidney is slightly enlarged, capsule strips easily leaving a smooth, purplish red surface; section surface is glistening, moist and exudes blood; consistency is slightly softened; cortical striæ very distinct. The bulging cut surface and poor demarkation of cortex and medulla characteristic of acute nephritis are present. The organ shows fat globules in the expressed blood. The adrenals are very small, firm, brown, bean-shaped bodies with a brownish medulla. The bladder is slightly distended with turbid urine. Urine shows dark granular casts, compound granule cells, spermatozoa and a positive Fehling’s test. Prostate is large and firm and a turbid material exudes from external meatus. The mouth shows several decayed teeth. In the neighborhood of last molars on left side of upper jaw a bead of pus exudes; further pressure results in no greater flow. The stomach is distended with a great quantity of undigested food and gas; no worms. Serosa and wall normal but anemic. Duodenum normal. Jejunum contains numerous worms about 1 to 1.5 cm. long; it is distended with gas. The pancreas is large, soft, like fat, white; it extends between the layers of mesentery along the course of the duodenum; at first the pancreas was mistaken for fat.

HISTOLOGICAL NOTES.—Spleen shows a distinct overgrowth of trabeculæ. Beyond this there is nothing pathological. Liver shows distended portal venules in which there are chains of bacilli. There is no especial fibrous overgrowth of capsule of Glisson; capillaries are choked with shadow corpuscles and here too, long chains of bacilli may be seen; parenchyma cells show postmortem change. Adrenal is the seat of postmortem degeneration, not congested, nor is there any evidence of bacterial invasion. The kidney shows no interstitial changes, in fact the section seems to be entirely normal save for moderate congestion. Vessels show no bacteria.