LEAD POISONING. PLUMBISM.

Physiological action on nervous system. Sources: near smelting furnaces on vegetation; paints; paint scrapings in manure and on soils; lead packing of pumps, engines, etc.; sheet lead; bullet spray; wall paper lead; leaden water pipes or cisterns; lead acetate; painted buckets; painted silo; lead compounds in arts. Experiments on animals. Accidental poisoning: horse, fever, gray nasal discharge, salivation, convulsions, paralysis, dyspnœa. Cattle, emaciation, dyspnœa, palsy, tonic spasm of flexors of limbs, swollen carpus, death in a few months. Young worst. Sheep, lambs paretic. Swine in pens escaped, those at large suffered. Post mortem; lead or lead compounds in stomach, or shown by analysis, in gastric contents, liver, spleen, kidney, etc. Tests. Treatment: hydrosulphuric or sulphuric acid, sulphate of magnesia or soda, antispasmodics; in chronic cases, potassium iodide, bitters.

The physiological action of lead is exerted on the nervous system, so that lead poisoning may be appropriately enough treated of as a disease of the nervous system.

Sources. The sources of lead as a poison for animals are extremely varied. In England in the vicinity of lead mines and smelting furnaces it is deposited from the air in a fine powder, and consumed with the vegetation. Herapath found that the deposit, in dangerous amount, began half a mile from the chimney of the smelter and extended about half a mile further.

A second source is in lead paints used about farms and the scrapings of paint pots thrown out with manure and spread upon the fields. These lead combinations will last for years in the soil or on the surface, being plowed under one year and turned up again the next when the occasion of their presence has been completely forgotten. In one case I found the red lead paint marked by the tongues of cattle at the back of an abandoned cottage the fence around which had been broken down. In another the scrapings were found in an orchard which had been near and convenient for throwing them out. In a third case a paint can hung on the branch of an apple tree, well out of the way of the stock as the owner fondly supposed, showed in its contents the marking of the barbed tongues of the cattle. In a fourth case a barrel of paint was set under the barn where there was not height enough to admit the matured cattle, but it bore the marks of licking by the young stock, and they alone died but in such numbers that the owner concluded it must be the “Rinderpest.”

The lead packing from the joints of pumps, engines and other machinery, thrown away around works and mines, is a common source of the trouble. I once found large quantities in the gastric contents of cows that had died around a coal mine in Ayrshire, Scotland.

Sheet lead—tea-chest lead—is another common source of the poison. This is thrown out, scattered with the manure on the field, and will resist the elements for years but dissolves when taken into the acid stomach of the animal.

The spray from bullets in the vicinity of rifle butts is another common cause of the poisoning.

In one instance I have seen a cow poisoned by eating some lead-impregnated wall paper which had been carelessly left in the stable.

Less frequently the poisoning comes from drinking water carried in leaden pipes, or left to stand in a leaden cistern. The softest waters—rain, snow, distilled water—are the most liable to this impregnation. The hard waters containing carbonates, sulphates or phosphates, tend to be decomposed, the acid uniting with the lead to form comparatively insoluble carbonates, sulphates or phosphates of lead, which protect the subjacent lead against solution. The hardness of the water is not, however, a sufficient safeguard, as iron, solder, and other agents present in the lead as an impurity or merely resting upon it, are sufficient to set up a galvanic action resulting in solution.

The salts of lead may find direct access to the animal, as in the case reported by Gamgee in which a farmer used a barrel which had contained acetate of lead for mixing the feed given to his stock. A somewhat similar source of poisoning is found in the use of buckets or silos which have been painted inside, and scale off in contact with hot water, etc.

Blythe enumerates the following compounds of lead as employed in the arts:

1st. Hair dyes which have a basis of litharge, acetate or carbonate of lead in combination with lime and other agents.

2nd. White lead in its various forms is carbonate of lead.

3rd. Newcastle white is white lead made with molasses vinegar.

4th. Nottingham white is white lead made with sour ale.

5th. Miniature Painter’s white is lead sulphate.

6th. Pattison white is an oxychloride of lead.

7th. Chrome Yellow is impure chromate of lead.

8th. Turner’s Yellow, Casella Yellow, Patent Yellow is oxychloride of lead.

9th. Chrome Red is a bichromate of lead.

10th. Red Lead is the red oxide of lead.

11th. Orange Red is an oxide obtained by calcining the carbonate.

12th. Nitrate of Lead is much used in calico printing.

13th. Pyrolignite of Lead is an impure acetate used in dyeing.

14th. Sulphate of Lead is a by product in the preparation of acetate of aluminium for dyeing.

Forms. Lead poisoning occurs in acute and chronic forms. The two forms, however, merge into each other and are largely convulsive and paralytic.

Experimentally. Harnack found that 2 to 3 mgrms. in frogs and 40 mgrms. in rabbits caused increased intestinal peristalsis, diarrhœa, and paralysis of the heart. Dogs had choreic symptoms. Gusserno gave 1.2 grm. to rabbits and dogs respectively, and produced emaciation, shivering and paralysis of the hind extremities. Rosenstein with 0.2 to 0.5 grm. obtained in dogs similar symptoms with epileptiform convulsions, and Heubel had symptoms of colic in a few cases.

Casual or Accidental Poisoning. Metallic lead is slowly dissolved and therefore large doses of this may be taken in without visible ill effect. Shot has often been given to relieve the symptoms of broken wind in horses, and a dog at the Lyons Veterinary School took four ounces without visible ill effect. When finely divided, however, as in sheet lead or the spray of bullets it presents a much more extended surface to oxygen and acids, and in the acid stomach of monogastric animals, or even in the organic acids of the rumen it is dissolved in quantity sufficient to prove poisonous.

Symptoms in Horses. Shenton thus describes his cases. “There was a rough, staring coat, a tucked up appearance of the abdomen, and a slightly accelerated pulse; in fact, symptoms of febrile excitement which usually, however, passed away in about a week. About this time large quantities of gray colored matter were discharged from the nostrils, and saliva from the mouth, but at no time was there any enlargement of the submaxillary, lymphatic, or salivary glands. Nor was there constipation of the bowels, which appears to be nearly always present in cases of lead poisoning in man. Fits and partial paralysis came on at intervals; and when the animals got down they often struggled, for a long time ineffectually, to get up again. The breathing up to this time was pretty tranquil, but now became so difficult and labored that the patient appeared in danger of suffocation. The pulse was in no case above 60 or 70, and I ascribe the difficulty of respiration to a paralyzed state of the respiratory apparatus. The animals did not live more than two or three days after these symptoms appeared. The post mortem appearance varied but little. The lungs and trachea were inflamed; the lungs engorged with large quantities of black blood; the trachea and bronchia filled with frothy spume. In all cases but two the villous part of the stomach presented isolated patches of increased vascular action, and in all cases the intestines, and especially the large ones, were inflamed. The blind pouch of the cæcum was nearly gangrenous. There was nothing remarkable about the liver, spleen or kidneys, except that they were of a singularly blue appearance.”

Symptoms in Ruminants. These are described by Herapath as following the erection of lead smelting furnaces in the Mendip Hills in Somersetshire. There were stunted growth, emaciation, shortness of breathing, paralysis of the extremities, particularly the hinder ones, the flexor muscles of the fore limbs affected so that the animals stood on their toes, swelling of the knees and death in a few months. Even if removed to a healthy locality the victims failed to thrive. The effects were most pronounced in the young. Lambs were born paralytic; at three weeks old they could not stand, and palsy of the glottis rendered it dangerous to feed from a bottle. Twenty-one out of twenty-three died early. The milk of cows and sheep was reduced in quantity and quality, and contained traces of lead. The cheese had less fat in it. The dead showed the mucous surfaces paler than natural and the lungs had large areas with abruptly circumscribed margins of a dark red color, surcharged with fluid. A blue line appeared on the gum close to the teeth, and from this a globule of lead could be melted under the blowpipe.

In the cases that have come under my observation paralysis of the hind limbs, emaciation and low condition, have been most prominent in the chronic forms, while these have been complicated by torpor of the bowels, blindness, stupor, coma, and more or less frequent paroxysms of delirious excitement or convulsions in the acute. In the chronic cases the blue line on the gums is an important symptom.

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.03to.10per cent.
Kidney.03to.07„ „
Brain.02to.05„ „
Bones.01to.04„ „
Muscles.004to.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.