Herapath noticed that near the smelting furnaces pigs escaped if kept in the pen but suffered if allowed to go at large. This is explained by the presence of lead in the forms of oxide, carbonate and sulphate on the herbage, hay and hedge rows, and in short, on all vegetation.
In post mortem examination the stomach should be carefully searched for lead in the metallic form as sheet lead, bullet spray, etc., for the different forms of paint of which lead forms an ingredient, for the discarded white lead packing of pipes and machinery, and even for solid masses of metallic lead. This is especially necessary in the case of cattle in which the morbid habit of eating non-alimentary matters is so common, and for which the sweet taste of some of the lead compounds seems to offer an attraction. The lead being long retained in the first three stomachs in contact with acetic and other organic acids is especially liable to be dissolved and absorbed in dangerous amount.
In the chronic cases especially, the test by electric current may furnish a valuable pointer. In lead poisoning the muscles respond much less actively to the stimulus than in the normal condition.
In resorting to analysis the following table from Heubel of the amount of lead in the different organs of a dog may offer a guide to the selection of an organ for examination:
| Liver | .03 | to | .10 | per cent. |
| Kidney | .03 | to | .07 | „ „ |
| Brain | .02 | to | .05 | „ „ |
| Bones | .01 | to | .04 | „ „ |
| Muscles | .004 | to | .008 | „ „ |
Professor George Wilson found the lead very abundant in the spleen, and used it for analysis. He dissolved it in aqua regia over a slow fire, cooled, filtered, evaporated, cleared, and boiled with dilute nitric acid. Then filtered and dried again, dissolved in dilute muriatic acid, and finally applied the color tests. With hydrosulphuric acid it gives a black precipitate, with sulphuric acid, a white, and with potassium iodide or bichromate a bright yellow. Or from the solution of the chloride the lead may be obtained as a metallic deposit on zinc from which it can be fused into a minute globule on charcoal.
In the treatment of lead poisoning the first object is to prevent the further solution of lead in the alimentary canal and to carry it off. To fill the first indication, hydrosulphuric acid or sulphuric acid may be administered to form respectively the insoluble sulphide or sulphate. As a purgative, sulphate of magnesia or soda should be preferred, as favoring at once elimination and the formation of an insoluble precipitate. Large doses are usually desirable, especially in ruminants, because of the bulky contents of the stomach and the torpor of the alimentary canal. If griping is a prominent symptom opium or other antispasmodic must be added.
In chronic cases, after the evacuation of the contents of the alimentary canal small daily doses of potassium iodide will serve to dissolve the lead out of the tissues, while sulphates may be given in small doses to assist in elimination from the bowels and to prevent reabsorption. The treatment by potassium iodide is equally applicable, to assist in the elimination of the lead that has passed into the circulation and tissues. The doses, however, should in any case be small to avoid the sudden solution of a large amount of lead which had been deposited in the tissues in a comparatively insoluble form. The sudden entrance into the circulation of any large amount of such lead would induce a prompt return of the toxic symptoms. A continuous exhibition of small doses is the course of wisdom and safety. The bowels should meanwhile be kept somewhat relaxed by small doses of sodium or magnesium sulphate. As a general tonic a course of bitters may be called for, especially when torpor or emaciation is pronounced.
ALCOHOLIC INTOXICATION.
Beer in pigs, alcohol in dogs, absinthe in horse, alcohol and burnt ales in cows, alcoholized grain in fowls, also fermented raisins. Symptoms, lack of coördination, staggering, flushed mucosæ, full pulse, stertor, sopor, coma, alcoholic breath, chill, muscular twitching, delirium. Treatment: ammonia acetate, or carbonate, apomorphia, pilocarpin, warm water, coffee, stomach pump, electricity.