Circumscribed or diffuse gangrene, as a primary condition, is rarer. Infective organisms rapidly invade even the depths of the gland, the interstitial and subcutaneous tissue, and thrombosis due to infection or intoxication occurs, followed by gangrene. Death results from infection or intoxication.
Complications such as necrosis of the abdominal tunic, of the fibrous tissue enveloping the mamma, and of the muscular layers on the inner surface of the thighs, may occur in the suppurative forms.
Diagnosis. The diagnosis of acute mammitis is easy, and the interstitial forms (mammary lymphangitis) can be distinguished from the parenchymatous forms very early in the attack.
Careful examination suffices to differentiate between this condition and mammary congestion or primary chronic mammitis. The examination, however, must be much more thorough and searching when a specific disease (such as tuberculous mammitis) is in question.
Prognosis. The prognosis of acute mammitis is always grave, whatever form the disease may assume, for, if the animal’s life is not invariably endangered, its economic value is always affected. Moreover, should superficial or deep-seated abscesses form, prolonged suppuration may follow, resulting in loss of condition and enormous depreciation.
Lesions. The lesions of interstitial mammitis are similar to those of ordinary lymphangitis, the condition originating near the teat and gradually extending to the layers of connective tissue between the acini, mammæ, etc.
In the parenchymatous form the inflammation may remain partial, and be localised in particular tracts of glandular tissue. The secreting epithelium, when infected, exhibits cloudy swelling, becomes loosened, and disappears; the margin of the gland and the interstitial divisions become infiltrated with enormous numbers of white blood corpuscles, and are the seat of suppurative processes which end in the production of small acinous abscesses. By the union of neighbouring abscesses large branching collections of pus are produced, and lead to partial or total destruction of tracts of the parenchyma, of the connective tissue divisions, vessels and aponeuroses.
The abscess tends to break through the skin, which becomes inflamed and ulcerated, or, when the microorganisms are of slight virulence, the tissues may react, so that the abscess becomes surrounded with a thick indurated wall, and finally encysted.
Treatment. Very numerous methods of treatment have been proposed, an admission which, in itself, suggests that no perfect one has been discovered. No infallible system, in fact, exists of arresting the disease and restoring the parts to their normal condition.
From a prophylactic standpoint, mammitis can be avoided by placing the animals under proper hygienic conditions, paying special attention to cleanliness, avoiding overstocking, and treating excoriations or injuries to the teat or udder as soon as they appear.