Nevertheless, under certain circumstances the development of nephritis may be arrested at the primary congestive stage, and it is only then that an opportunity occurs of studying it as a definite complaint.
Causation. All infections accompanied by lesions of the kidneys, and these are numerous (gangrenous coryza, anthrax, parasitic hæmoglobinuria), produce congestion of the kidneys.
Cold also acts directly under certain conditions, as do large doses of diuretics, irritant foods the principles of which are eliminated through the urine (fermenting or putrid sugar-pulp, for example), and foods rich in resins, essential oils, various glucosides, tannin, etc. (young shoots of trees during the spring-time).
Symptoms. The symptoms are difficult to define accurately, and the diagnosis can only be arrived at with the aid of the history.
Renal congestion produces pain, indicated by dull colic and repeated and ineffectual attempts to urinate, suggesting acute cystitis. The patients lose appetite, and present all the general symptoms of marked visceral inflammation, viz., fever, acceleration of breathing, somewhat tumultuous action of the heart, etc.
External or internal examination of the kidneys reveals abnormal sensitiveness. The urine is of a dark or bright-red tint, owing to the presence of red blood corpuscles. These blood corpuscles are precipitated on placing the fluid in a tall glass, and can be detected, together with renal epithelium, by microscopic examination.
The diagnosis is somewhat difficult, and it requires very careful attention to distinguish between congestion of the kidney and true nephritis.
The prognosis should always be reserved until it is certain that acute nephritis will not ultimately develop.
The treatment consists in removing the cause of the congestion; rich foods, or foods containing irritant principles, should, therefore, be avoided, as also the administration of diuretics, etc.
Otherwise, the treatment is similar to that employed in all visceral inflammations: bleeding to the extent of two to four quarts, according to the size of the animals, warm poultices to the loins and flanks, dry friction, mucilaginous drinks and emollient decoctions of barley or pellitory. The animals should be kept in a warm place.