When suppurative nephritis has resulted from accidental infection of internal origin, an abscess is found to have produced more or less extensive atrophy of a portion of the kidney while not affecting the rest of the organ.
It is only in those favourable cases where the renal abscess opens into the pelvis that suppuration may invade the whole of the kidney, producing diffuse suppurative nephritis by secondary infection of the uriniferous tubules. Such complications are rare. Usually the abscess empties through the pelvis, and recovery may occur.
More frequently suppurative pyelo-nephritis develops, together with ureteritis, cystitis, dilatation of the ureters, dilatation of the pelvis of the kidney, and dilatation of the collecting tubules of the pyramids, the final stage resembling the lesions of pyo-nephrosis.
Perinephritis and perinephritic cellulitis, i.e., inflammation with or without abscess formation in the connective tissue and adipose layer surrounding the kidney, always occur in cases of suppurative nephritis or pyelo-nephritis. Such inflammations may also, in exceptional cases, follow direct mechanical injury, but they almost invariably represent complications, the organisms infecting the kidney passing through the tissues and the layer of fibrous tissue, or extending by the lymphatic paths, finally attaining the fatty tissue surrounding the kidney and there undergoing multiplication. The fatty tissue is infiltrated with reddish serosity, is inflamed, and may become the seat of large abscesses communicating with or separate from the abscesses of the kidney itself.
Symptoms. Suppurative nephritis is characterised by fever, loss of appetite, arrest of rumination, and frequent attempts to urinate. These attempts are painful, are accompanied by groaning, and end in the passage of an insignificant quantity of blood-stained and purulent urine.
Palpation, more especially palpation of the right flank, percussion over the region of the loins, and examination of the kidneys through the rectum are painful. Wasting is rapid.
If the suppurative nephritis develops rapidly, and particularly if it be accompanied by perinephritis, the patients refuse to rise and appear to be suffering from paraplegia, although not really so, both sensation and motor power persisting in a greater or less degree. Probably the condition is accompanied by reflex pain and irritation of the nerve trunks of the lumbo-pubic plexus.
On the other hand, when suppurative nephritis tends to develop slowly and assume a chronic form, lesions of pyo-nephrosis gradually develop, and are identical in appearance with those of hydro-nephrosis, except that the ureters, the pelvis and the dilatations corresponding to the lobules, are filled with pus.
Fig. 231.—Leaf lard around kidney of pig.