Diseases of cattle, sheep, goats and swine

by G. Moussu; Jno. A. W. Dollar

The classification adopted in the following pages is as follows:—

Mammitis	Acute	Primary	Parenchymatous or galactogenous.
			Interstitial or lymphogenous.
		Secondary or symptomatic.	Hæmatogenous.
			Galactogenous.
	Chronic	Primary	Simple.
			Parenchymatous.
			Interstitial.
		Secondary	Parenchymatous.
			Interstitial.

We shall leave on one side everything concerning secondary symptomatic mammitis, the study of which merges into that of the general diseases from which it arises.

ACUTE MAMMITIS.

Causation. The general cause of acute mammitis, like that of chronic mammitis, is infection by pathogenic organisms, whether such organisms enter by the usual natural path, viz., the galactophorous sinus and excretory apparatus, by the lymphatic path, owing to some accidental injury, or, again, by the blood circulation.

Infection of the lymphatics undoubtedly plays a part in superficial and interstitial inflammations, and it is proved that certain microorganisms may pass into the milk, as it has been proved that they pass through the kidney.

But if infection is the determining cause, certain secondary favouring influences must not be overlooked.

Thus lactation is an almost indispensable condition. It is true that some cases of mammary inflammation apart from lactation have been described, but they have been the result of violence, accidental or mechanical.

Accumulation of milk in the udder (overstocking) has unquestionably a certain influence in the large milk-yielding animals, not because it directly produces inflammation, but because milk then escapes spontaneously; and as the udder cannot be entirely evacuated without external assistance, the entrance is kept permanently open for the passage of germs, which are freely transferred to the teat from the litter and surrounding objects.

Cold, or rather chills, also act in a complex manner, particularly by disturbing vaso-motor control. Different forms of mechanical violence, such as blows, crushing strains, wounds, etc., may immediately and directly set up local or general inflammation.