Definition. Affects birds, dogs, perhaps pigs. Causes: excess of
nitrogenous food, imperfect oxidation, impaired metabolism and
elimination. Susceptibility of birds in confinement. Xanthin bases.
Nuclein. Hepatic torpor. Contracted kidney. Affects tissues of little
vascularity. Lesions: chalky deposits around joints, and in internal
organs. Solubility of biurate of soda in synovia, serum, etc.
Symptoms: arthritis, joint tenderness, resting on breast, hard or
fluctuating swellings, desquamation, ulceration, chalky urates.
Diagnosis: test for biurate. Treatment: less albuminoid diet,
eliminating salts, colchicum, piperazin, surgical and antiseptic
dressing.
_Definition._ An arthritis characterized by periodical exacerbations, by
the deposit of sodium biurate in and around the joints and at times in
other parts of the body, and by more or less constitutional febrile
disturbance during the paroxysms.
_Animals susceptible._ Among the lower animals the disease has been
noticed almost exclusively in birds, which even normally excrete so much
uric acid that the liquid may be semi-solid as found in the cloaca or in
the droppings. While this is a constitutional peculiarity in the bird
yet it is enhanced in connection with an abundant diet of rich
nitrogenous materials, as in forced feeding, and in old animals in which
the eliminating action of the kidneys is more or less impaired. Ebstein
has shown that gout can be produced in birds by tying the ureters. All
domesticated birds, chickens, turkeys, pigeons, ostriches, geese, ducks,
Guinea fowl, have been found to suffer. A case of gout has been reported
in a =dog=, and Pradal has described it as existing in swine, but the
symptoms given are more in accord with articular rheumatism.
_Causes._ The causes of gout are overfeeding especially on highly
concentrated nitrogenous food, acid sweets, and in turn sweet and acid
alcoholic drinks, an excess of uric acid in the blood and tissues,
imperfect oxidation of albuminoids, impaired metabolism, imperfect
elimination of uric acid, and impaired innervation. Probably no single
morbid condition is in itself sufficient to induce the disease but a
combination of several, unquestionably operate in many cases.
The uric acid theory is favored by the constant presence of this acid in
considerable amount in the blood of birds, and by Ebstein’s experiment
in tying the ureters, but it has to face the fact that young and active
birds living in the open air, and hunting for their food do not suffer,
that it is usually scanty in the blood of man just before an attack,
that Gilman Thompson failed to produce any symptoms of gout by injecting
into the blood of animals more uric acid than the amount which they
normally excrete in twenty-four hours, that the familiar symptoms of
uric acid poisoning are not at all those of gout, and that the excess of
uric acid in leucæmia, anæmia and pneumonia produces no such symptoms.
In addition to excess of uric acid some other factor is required.
_Xanthin bases_ (Xanthin, hypoxanthin, etc.) found in the blood by
various observers, are derived from albuminoids, especially nuclein and
nuclein bases, including in man caffein and theine, and being closely
allied to uric acid are believed to have a nearly similar action.
Various forms of abnormal metabolism are invoked as the cause of uric
acid and gout, and Haig and Vaughan hazard the theory that the breaking
down of the nuclein is an important factor. This and other metabolisms
are attributed to the local action of the uric acid and urates, and
again to a fault in innervation. The imperfect action of the liver where
the uric acid should be largely resolved into the more soluble urea, and
of the kidneys through which it should be promptly excreted must be
attributed to a nervous source. Levison incriminates the granular,
contracted, inactive kidneys.
Ebstein attaches great importance to impaired nutrition in the affected
tissues which undergo necrotic changes that pave the way for the
deposition of urates in their substance. This is somewhat sustained by
the occurrence of the local deposits in tissues in which circulation and
nutritive changes are slow, and in older animals in which not only are
the osseous tissues more calcic and less vascular, but the articular
lamella has been formed by cretefaction of the bone and cartilage. Haig
suggests that in the old, the joints are less vascular and less
alkaline, and more sensitive to cold. On the other hand those in the
greatest vigor of life are more ravenous, digest more actively and are
in this sense more subject to injury from excess of uric acid and allied
products. Birds at this age, confined and in process of fattening are
thereby exposed. Overfed, obese, lazy, old house dogs are under similar
causative conditions.
_Lesions._ The most prominent lesions in birds are chalky concretions of
urates on the articular ends of the bones and in the structures around
the joints including even the tendons, with more or less inflammatory
exudate and even necrosis, invading the bony tissue and articular
cartilage. Abscesses may be present usually outside the bursa. Birds
suffer especially in the tarsal, metatarsal and phlangeal joints, but
often also in the corresponding joints of the wing, and less frequently
in the joints of the trunk, and in the internal organs,—kidneys, liver,
lungs, serosæ,—and skin. In these last, miliary chalky concretions and
encrustations are found. In Brückmüller’s case in the dog the chalky
deposits of urates were found mainly on the epiphyses of the ribs, but
also on the joints of the limbs.
Uric acid is always abundant in the blood of birds, and Roberts has
shown that biurate of soda (the usual form of precipitate) is insoluble
in blood serum, synovia and other body fluids when in excess of
1:10,000.
_Symptoms._ In birds the febrile and constitutional symptoms have not
been carefully observed so that the objective symptoms in the affected
joints have been mainly relied on. There is extreme tenderness marked by
standing on one limb, or resting on the breast, and hence moping apart
from the flock. When made to rise, the affected limb may be used to
steady the body, or even to walk, with a limp, though in bad cases the
sound limb only may be used. The affected joints are swollen, soft, hot,
extremely tender, pitting on pressure, and later the seat of nodular
yellow masses, usually hard, but sometimes fluctuating and in size from
a pea to a hazel nut. The superimposed epidermis is thick, dry and
scaly, falling off in flakes. At a more advanced stage the concretions
may burst through the skin, discharging a buffy, granular, debris
containing crystals of urates of ammonium or calcium, or of uric acid.
Later still are ulcerous sores, involving the disintegrating urate
nodules and the necrotic bones and cartilages. The deposits deflect the
bones from their normal direction, causing not only nodular swellings on
the toes but much crookedness and distortion. As in man the disease is
essentially chronic and advances slowly, with anæmia, emaciation,
debility and at times diarrhœa.
_Diagnosis_ depends largely on the recognition of the excess of urates
in the deposits. These appear under the microscope as fine acicular
crystals, which in the harder portions have a concentric arrangement. A
portion of the concretion may be moistened with a few drops of nitric
acid and evaporated to dryness. To one part of the residue is added, by
means of a pipette, a drop of aqua ammonia, and to another caustic soda.
The ammonia develops a beautiful purple red color, and the soda a blue
or purplish blue ring (Murexide test). In tubercular joints, which are
common in birds, the caseated nodule is made up of cells and granular
debris, with tubercle bacilli, and though cretaceous particles may be
present they fail to give the microscopic and color appearances of uric
acid.
_Treatment._ This must be largely preventive. The rich albuminoid
feeding and close confinement must be modified especially in the older
birds, and eliminating agents must be given in the drinking water. The
Carlsbad combination (sodium sulphate 22; potassium sulphate 1; sodium
chloride 9; sodium bicarbonate 18) may be used. Powdered colchicum ¼ gr.
once or twice daily during an attack, or piperazin ½ gr. twice a day.
Locally, abscesses should be opened, and like any sores or ulcers,
treated with antiseptics (Salicylate of sodium 75 grs., glycerine 2
ozs.; or piperazin solution 2:100).