Lesions. There may be a circumscribed renal abscess like a good large orange, or many small gray spots like millet seeds, peas or hazel nuts, having purulent centres and containing pus cocci or bacilli. In other cases a diffuse inflammation suppurates throughout till the whole gland becomes a pulpy mass of pus, blood and broken down kidney tissue (pyonephrosis). In traumatic cases the pus centres around the wound or injury, perhaps invading adjacent parts, and even communicating through the skin externally along the line of the original wound. The pus may burrow in different directions in the cortex or under the capsule with abscess at intervals (perinephritis), or along the vessels to the medullary structure.
Symptoms. These are often obscure. The sudden appearance of kidney disease in the course of a suppurative affection elsewhere, the extension being ushered in by a chill or rigor or attended by a succession of these, and the course marked by a variable hyperthermia is very suggestive. Stiffness and weakness of the hind parts and tenderness of the loins are significant; also, in carnivora and omnivora, nausea and vomiting. When the kidney can be felt by the hand in the rectum or in the small animals, through the flaccid abdominal walls, the manifest enlargement, the tenderness, and in some cases even fluctuation will assist in diagnosis. In such cases, puncture by a large hypodermic needle, or a small trochar may betray the presence of pus and complete the diagnosis. If the pus escapes into the pelvis of the kidney it may be recognized in the urine. The case is very liable to become chronic, and is then marked by anæmia and emaciation.
Treatment. When an external wound exists it must be treated, antiseptically, with boric acid, potassium permanganate, or other antiseptic lotion. If a single large abscess exists, puncture evacuation through needle or trochar, and washing out with an antiseptic solution is the obvious resort. Any foreign body must of course be removed. If the suppuration is diffused through the whole mass of softened kidney, the resort of extirpation may be considered. This is always dangerous as provocative of infectious peritonitis, but it is less so in dogs and swine than in other animals owing to their natural antagonism to pus microbes. The operation should be attempted extraperitoneally, the incision being made beneath the anterior lumbar transverse processes and carried inward through the sublumbar connective tissue. The renal artery will require ligature with antiseptic catgut and all manipulations should be aseptic or antiseptic. Even if successful, this operation leaves the subject in a dangerous state, as in case of kidney disease at any future time, there is no second kidney to compensate for the temporary loss of function and uræmic poisoning is to be dreaded.
Apart from surgical measures the general treatment would be largely the same as for acute infectious nephritis. As antiseptics calcium sulphide, the different sulphites, copiaba, etc., will be indicated.
PERINEPHRITIS.
Definition. In cattle on low damp lands, acrid plants, sprain, blow, calculus, from purulent nephritis, in anæmia. Symptoms: of nephritis, soiling of tail or prepuce, albumen, pus or blood in urine, lameness, unilateral or bilateral, lumbar swelling, in small animals fluctuation, history. Lesions: abscesses around kidney, under capsule, intercommunicating. Treatment: as in purulent nephritis.
Suppuration in the connective tissue between the kidney and its capsule is seen in cattle in low condition, on damp, unimproved soils like undrained river bottoms and estuaries, abounding in acrid and diuretic plants. Even among such animals it is rare and has probably a directly exciting cause in a sprain or blow on the loins, or the presence and movement of a renal calculus. It may extend from suppurations in the substance of the kidney and to such extension the weak or anæmic condition materially contributes. In man, in which such conditions have been more frequently observed, a weak or cachectic condition is considered as an essential accessory factor along with the traumatic lesion (R. Harrison). Similar conditions may be expected to bring about perinephritis in any one of our domestic animals. The author has observed it especially on the low lands on the banks of the Ouse in Yorkshire, England.
Symptoms. These are mainly those of nephritis in general, shivering, stiff movement in the hind limbs, straddling, frequent passage of urine, straining, difficulty in lying down and rising, tenderness of the loins, dropping when mounted, groaning when turned in a short circle. If the suppuration communicates with the pelvis of the kidney there may be, in females, soiling of the tail, and in males of the prepuce. Blood may be passed with the urine, and pus cells and albumen are found when it is examined. If one kidney only is affected, there is lameness in the corresponding hind limb, the special feature being inability to extend it backward. A swelling on the one side of the loins, and beneath the lumbar transverse processes just posterior to the last rib, is likely to be a marked symptom, and if this persists and is especially prominent at one point, an exploratory incision or puncture will detect the presence of the pus. Fluctuation can rarely be detected, yet in small animals with very flaccid abdomen, the swollen, tender kidney and even fluctuation should be detected at times. The history of the case, the low, damp pasturage, the access to acrid plants, the alimentation with hay or grain covered with cryptogams, the fact of an injury and the low, weak, anæmic condition of the animal should contribute to a satisfactory diagnosis.
Lesions. In bovine kidneys affected in this way we have found general inflammation and exudation around the entire kidney and inside the capsule, with numerous small abscesses, in many instances communicating with each other. They may extend through the capsule and invade surrounding organs.
Treatment. In the treatment of cases of this kind the general principles of therapeutics for nephritis are about all that can be attempted in the lower animals. Fomentations over the loins are especially desirable as a means of relieving the suffering, and moderating inflammatory action. To the same end is the allowance of plenty of pure water as a diluent. Then the various agents that antagonize suppuration may be thought of, and some one selected for use. Beside the antisuppurants already mentioned one may use copiaba, cubebs, or turpentine in small doses, salicylates, or the sulphide or sulphite of calcium. Surgical interference by puncture or incision and antiseptic irrigation can only be thought of when the abscess is single and circumscribed; never when the whole periphery of the organ is involved. In the latter case the only rational surgery would be the desperate resort of the removal of the entire kidney.