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.