Under ordinary circumstances, however, the reasons are quite different, and when the secretion of milk is diminished or suppressed it is due to the ingestion of plants, substances, or drugs which check the secretion of milk. All the solanaceæ (belladonna, hyoscyamus, stramonium, woody nightshade, etc.), certain umbelliferæ (hemlock), colchicum, etc., have this effect.
As to agalaxia of a true pathological character, it occurs in debilitating and grave diseases, and sometimes follows certain contagious forms of mammitis complicated with sclerosis of the udder (infectious agalaxia of goats).
Diagnosis. The diagnosis of agalaxia presents no difficulty.
Prognosis. The prognosis varies, according to the determining cause. In cases of accident and in temporary agalaxia, it is sufficient to change the food in order to restore the secretion. Cooked food and warm drinks, with an allowance of roots such as turnips or mangolds, have excellent results. Where restoration of the secretion is delayed the use of what are called galactogogues has been recommended, comprising fennel, carraway, cummin, aniseed, juniper, sulphur, etc., mixed in equal parts and given in doses of 6 to 8 drachms per day for a cow.
They act principally through the stimulating effects of their aromatic principles.
MICROBIC CHANGES IN MILK.
LACTIC FERMENTS.
Microbic changes in milk are much commoner than changes of a chemical nature. Milch animals differ very markedly one from another, and, according to circumstances, give milk of ordinary composition, milk of a very rich character, or watery milk; but the most important changes in composition are those due to microbic agents.
During the milking, and according to whether this is performed in a low, dirty byre, in a clean, roomy byre, or in the open air, various numbers of germs obtain entrance to the milking vessels, and develop there with extraordinary rapidity. The milk may even become infected by non-pathogenic germs while still within the udder, in the sinus and galactophorous canals. The cleanliness of the milking vessels also has a considerable influence on the number and variety of the microbes which may eventually germinate in the liquid.
Among the microorganisms usually found in milk there are some, however, which always preponderate and play the part of organised ferments, viz., the lactic ferments and the organisms which cause coagulation of the casein; these may be regarded as normal constituents. The others are more or less foreign, and may cause important changes in the milk or cream.