The administration of a dose of purgative medicine too large for the patient, or its repetition in too short a time. It often happens that an aloetic ball is given without due preparation, and failing to have the desired effect within the usual time, the inexperienced attendant repeats the dose, with the result that the bowels are unduly excited. Drinking a great quantity of cold water when the ball has been given on an empty stomach, or calling upon the patient for too much exertion before the purgative has ceased to act, will also induce it in some susceptible animals. Calomel, even in small doses, will sometimes provoke superpurgation when given during an attack of influenza fever, as is sometimes done where bilious complications arise.
Frequent and excessive evacuation of the fluid contents of the bowels, loss of appetite, cold extremities, weak pulse, and in severe cases, in which there is considerable danger to life, the eyes assume a glassy appearance, and the odour of the breath and that of the evacuations become very offensive. There is great prostration and weakness; and pain and straining, more or less severe, appear in the course of the attack. Purging may cease on account of loss of power in the gut, or in consequence of a complete emptying of the bowel. With an abatement of the symptoms, laminitis, or "fever in the feet", supervenes in some cases, and adds to the existing trouble.
The surface warmth should receive immediate attention, hand-rubbing the legs, pulling the ears, bandaging and clothing with warm rugs; perfect quiet should be maintained, and if necessary the animal should be removed to a box away from the others. A gill of brandy, with an egg and a pint of milk, beaten up together, may be all that is needed in slight cases; but if abdominal pain follows, and the patient gets worse, astringent and anodyne medicines should be given, together with stimulants. Ounce doses of chlorodyne, with eggs and milk, or two ounces of laudanum with a wine-glass or two of brandy, may be tried, and repeated in two or three hours. Arrow-root, boiled rice, or corn-flour may be given in frequent doses, together with eggs and brandy, or spirit of nitrous ether. Treatment would be more successful but for the injudicious use of linseed and boiled roots, which would seem to be a common stable practice in some districts. In this disorder food may be dispensed with, excepting such as is described above; the sensitive bowels need rest, and the absence of all forms of irritation is imperatively indicated. When the abdomen assumes a drum-like condition, a wine-glass of spirit of turpentine may be given with milk, or an ounce of aromatic spirits of ammonia with peppermint.
Much care is necessary in bringing an overpurged horse back to his regular diet, if that be a strong one; he should be allowed only half-rations for some days, avoiding new, or any, hay or corn the least damaged. It is important, too, that the food be given in small quantities and often. Exercise will not be necessary beyond that to be obtained in a large loose-box.