Part 26

See similar reports in Veterinarian, vol. 68, p. 572, 1895, and vol. 69, p. 228, 1896; Zeits. f. Veterinärk., vol. 8, pp. 99 and 211, 1896; Nagler, F., Berliner Thierärztl. Woch., p. 65. 1896.

Dieckerhoff, W. Vet. Mag., vol. 2, p. 362. 1895.

Kabitz, H. Ueber d. Wirkung einiger Baryumsalze beim Schwein. Deutsch. Thierärztl. Woch., vol. 13, p. 317. 1905.

Parkes. Chem. Essays, vol. 2, p. 213. Quoted by Christison, R., in Treatise on Poisons, Edinburgh, 4 ed., p. 581, 1845.--Fuchs, C. J. Vergiftungsfälle durch salzsäuren Baryt beim Rindvieh. Thierärztl. Mittheil., vol. 5, pp. 133, 154. 1870.

Falk. Zur Vergift. von Hunden mit Chlorbarium. Berliner Thierärztl. Woch., p. 40. 1897.--Schirmer, Chlorbariumvergift. beim Hunde. Berliner Thierärztl. Woch., vol. 23, p. 268. 1897.

Linossier, G. De la Localisation du Baryum dans l'Organisme à la Suite de l'Intoxication Chronique par un Sel de Baryum. Comp. Rend. Hebd. Soc. de Biol., 8 s., vol. 4, p. 123. 1887.

NOTE.--Other cases of poisoning in animals may be found in Marder, Beitrag z. Giftwirkung des Baryum chloratum. Berliner Thierärtzl. Woch., vol. 37, p. 436. 1897; Absichtliche Vergift. mit Chlorbarium. Zeits. f. Veterinärk., vol. 9. p. 72. 1897.

=APPLICATION OF THE RESULTS OF THESE INVESTIGATIONS TO THE RANGE.=

It has been calculated that a medium estimate of food for cattle on green fodder is about 60 pounds (30 kilos) a day. Calculating this entirely in terms of Aragallus lamberti and allowing 10 per cent of moisture for these plants (Sayre) would make 27 kilos of dry loco eaten by each animal per diem. In the analysis of the writer of one Aragallus lamberti from Hugo, Colo., it was found to yield 12.44 per cent of ash, and the barium content corresponded to 2.6 milligrams BaSO{4} in each gram of the ash. This would correspond to 10.24 grams of barium acetate (Ba(C{2}H{3}O{2}){2} + H{2}O) or 9.15 grams of barium chlorid (BaCl{2} + 2H{2}O) per diem. This amount daily administered would, theoretically, readily produce chronic poisoning owing to the accumulation in the system, as was shown in the case of rabbits.

There is, however, some question as to whether this full theoretical amount of loco plants is eaten on the range, and the estimate has been made that one-sixth of this amount only would be actually taken. It must be remembered, as Stalker pointed out, that locoed animals develop an especial taste for these plants and after a time reject other food, so that while the number of loco plants at first taken may be small, yet later, perhaps, it is greater. A part of this barium, however, may not be taken up by the system, but may pass out undissolved. No actual experiments have yet been made with cattle by feeding small doses of the pure salt.

No doubt more of the pure barium salts will be required to produce symptoms of poisoning in animals than would be necessary in the case of the form of barium found in the plant, as in the loco-weed the barium is probably better protected from precipitation than are the barium salts when dissolved in water alone.

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FOOTNOTES:

Lane, C. B. Soiling Crop Experiments. N. J. Agric. Exper. Sta. Bul. 158, p. 18. 1902.--Woll, F. W. One Hundred American Rations for Dairy Cows. Univ. Wis. Agric. Exper. Sta. Bul. 38, p. 12. 1894.--N. J. State Agric. Exper. Sta., 20th Ann. Rept. (1899), p. 193. 1900.

CONCLUSIONS.

(1) Conditions analogous to those met with in locoed animals occur in other portions of the world, especially Australia.

(2) The main symptoms described in stock on the range can be reproduced on rabbits by feeding extracts of certain loco plants. Those especially referred to here under the term "loco plants" are Astragalus mollissimus and Aragallus lamberti.

(3) The production of chronic symptoms in rabbits is a crucial test of the pharmacological activity of these plants.

(4) The inorganic constituents, especially barium, are responsible for this action, at least in the plants collected at Hugo, Colo. Perhaps in other portions of the country other poisonous principles may be found.

(5) A close analogy exists between the clinical symptoms and pathological findings in barium poisoning and those resulting from feeding extracts of certain loco plants. Small doses of barium salts may be administered to rabbits without apparent effect, but suddenly acute symptoms set in analogous to what is reported on the range.

(6) The administration of sulphates, especially epsom salts, to form insoluble barium sulphate would be the chemical antidote which would logically be inferred from the laboratory work, but of necessity this would have to be frequently administered and its value after histological changes in the organs have occurred remains to be settled. But even the treatment of acute cases of barium poisoning in man is not always successful, even when sulphates combined with symptomatic treatment are employed. The conditions under which the sulphates fail to precipitate barium must be considered. At present it seems best to rely on preventive measures rather than on antidotal treatment.

(7) Loco plants grown on certain soils are inactive pharmacologically and contain no barium. In drying certain loco plants the barium apparently is rendered insoluble so that it is not extracted by water, but can usually be extracted by digestion with the digestive ferments.

(8) The barium to be harmful must be in such a form as to be dissolved out by digestion.

(9) In deciding whether plants are poisonous it is desirable not merely to test the aqueous or alcoholic extract, but also the extracts obtained by digesting these plants with the ferments which occur in the gastro-intestinal tract.

(10) It is important that the ash of plants, especially those grown on uncultivated soil, as on our unirrigated plains, be examined for various metals, using methods similar to those by which rocks are now analyzed in the laboratory of the United States Geological Survey.

(11) It is desirable to study various obscure chronic conditions, such as lathyrism, with a view to determine the inorganic constituents of lathyrus and other families of plants.

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FOOTNOTES: