Part 7

Martin experimentally studied these cases of intoxication and sums up his work as follows:

1. That one can by feeding sheep upon Darling pea reproduce all the symptoms which are attributed by pastoralists to this cause. Briefly stated these symptoms are: Stupidity, loss of alertness and an agonized expression, followed by stiffness and slight staggering and frequently trembling of the head or limbs. Later, clumsiness and unsteadiness ensue, which slowly advance until the animal often falls down. In this stage, the action of the animal in running over small obstacles is characteristic. It jumps over a twig as if it were a foot in height. When first it commences to tumble about, it is able more or less readily to regain its feet, but in the advanced stage of the disease this is impossible and, after exhausting itself in efforts to do so, it remains lying down until it dies. During the whole time the sheep become progressively more bloodless, and in advanced cases the blood when shed appears to the naked eye lighter in color. It contains fewer red blood-cells (about two-thirds to one-half the usual number). (The corpuscles were estimated in several cases by means of a hæmocytometer.) All these symptoms are much aggravated by driving. Thus, an animal in which the symptoms are little marked may exhibit them in a striking degree after being driven. In addition to the above the teeth (especially in young sheep) frequently become loose, and consequently displaced or even dislodged.

2. That the time which elapses before the onset of definite symptoms is three to four weeks in sheep of 2 to 3 years old. (It is probable, however, that with younger animals the time is shorter.)

3. That under the conditions of the experiment, the animals survived about three months. They lived, however, an invalid's life. Everything was brought to them, and it is improbable that if feeding exclusively upon the pea, and left to shift for themselves in the paddocks, they would survive more than two months.

4. That if a sheep be returned to proper fodder after one month to six weeks feeding upon the pea, and before the symptoms are fully established, it may recover completely.

5. That when once the paralytic symptoms are established it will not recover; but if returned to proper food, will remain in much the same condition, becoming neither better nor worse.

6. That Darling pea contains a very fair amount of nourishing material so that animals may, provided they eat it readily, retain their condition on it for some weeks, until the poisonous principle contained has had time to exert its effects.

These plants, if fed with other herbage, do not seem to be injurious and apparently lose their harmful action upon being cultivated. As long as salt is properly fed the animals will not eat this plant and are said to suffer no effects from it. Physiological study has shown the presence of a body with marked sudorific power which causes rapid emaciation in frogs.

It has been claimed that these symptoms are due to the presence of a narcotic poison in the plant. Post-mortem examinations were negative save for the presence of a peripheral neuritis.

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FOOTNOTES:

Maiden, J. H. Plants Reputed to be Poisonous to Stock in Australia. Dept. Agric., New South Wales, Misc. Pub. No. 477, pp. 15, 16. 1901.

Notes on Some American and Australian Plants Injurious to Stock. Agric. Gaz., New South Wales, vol. 4, p. 677. 1894.--Notes on Weeds. The Darling Pea. Agric. Gaz., New South Wales, vol. 3, p. 330. 1893.

Martin, C. J. Report on an Investigation into the Effects of Darling Pea (Swainsona Galegifolia) upon Sheep. Agric. Gaz., New South Wales, vol. 8, p. 366. 1898.

Woolls, W. On the Forage-Plants Indigenous in New South Wales. Linn. Soc., New South Wales, Proc., vol. 7, pp. 315-316. 1882.

Guthrie, F. B., and Turner, F. Supposed Poisonous Plant. Agric. Gaz., New South Wales, vol. 4, p. 86. 1894.

Bailey, F. M., and Gordon, P. R. Plants Reputed Poisonous and Injurious to Stock, Brisbane, 1887, p. 25.

Guthrie, F. B., and Turner, F. Supposed Poisonous Plant. Agric. Gaz., New South Wales, vol. 4, p. 87. 1894.

Martin, C. J. Report on the Investigation into the Effects of Darling Pea (Swainsona Galegifolia) upon Sheep. Agric. Gaz., New South Wales, vol. 8, p. 367. 1898. (Further literature on the indigo disease will be found in Bailey, F. M., and Gordon, P. R. Plants Reputed Poisonous and Injurious to Stock, Brisbane, 1887, p. 25).

NOTE.--In Canada a chronic disease associated with cirrhosis of the liver results from eating ragwort, or Senecio jacobaea. See Dept. of Agriculture, Canada, Rept. of Veterinary Director General, 1905, Ottawa, 1906, p. 31.--In South Africa a disorder known as nenta appears in goats after eating certain plants, especially Cotyledon ventricosa. See Hutcheon, D., Nenta, in Agric. Journ. Cape of Good Hope, vol. 14, p. 862. 1899.

=PATHOLOGICAL CONDITIONS IN LOCOED ANIMALS AS DESCRIBED ON THE RANGE.=

The pathological features as described by previous writers are a softening and ulceration of the stomach walls and a degeneration of the walls of the intestines with or without perforations. The peritoneum may be found inflamed. The peritoneum and omentum in one case (cow), reported by Sayre, were covered with small nodules. These were probably tubercular in origin. The colon in one horse was found enormously distended, while the coecum and small intestines were normal, save that the walls appeared thin.

Ulcers have been found at times in the kidneys, but were probably secondary in origin, as other cases are reported with normal kidneys. Faville has found in some cases amyloid degeneration. The pancreas and spleen are reported normal. The abdominal cavity may contain a slight effusion. The liver has been found cirrhotic, and at times shows tubercular lesions of a secondary nature. The inner coat of the bladder has been found softened, and in sheep the bladder may be markedly distended at the autopsy. The cerebral membranes are congested and perhaps adherent, and there may be blood clots over the longitudinal sinus or at the base of the brain. Effusions have been especially noted around the medulla. The arachnoid has also shown slight congestion, and in other cases the membranes showed a slight thickening. The middle ventricle was found filled with yellow serum, while the fourth ventricle contained a hemorrhagic effusion, and the base of the brain was covered by a clot. The hemorrhage may become organized and the brain be held to the membranes by tough organized fibers. In many cases serous effusion is present in the lateral ventricles. The arachnoid space is also in some cases similarly filled. Microscopic examination of the brain in the case of a steer showed atrophy of Purkinjie's cells.

In sheep the post-mortem examination showed paleness, anæmia of the muscles, and great distention of the abdomen. The intestines were found filled with gases, and the mesenteric blood vessels filled with blood. No peritonitis, or ascites, or ecchymoses in the mucous membranes were noted in the autopsies made on sheep by Ruedi. The liver has been seen enlarged. In sheep the brain was anæmic. Microscopically the brain showed atrophy and the Purkinjie's cells disappeared or their processes atrophied. In these sheep the brain was so anæmic that the distinction between the gray and the white matter was hard to define. The membranes of the cord have been found inflamed and adherent, but the spinal cord was usually normal. In some cases, however, the spinal cord has been found softened and oedematous. The arteries of the limbs were gorged with blood, and at the same time there was a collection of serum in the abdominal cavity. Death is thought to be due to starvation. In other words, the pathological condition, according to published accounts, shows little that is characteristic save some action on the gastro-intestinal tract.

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FOOTNOTES:

Anderson, F. W. Poisonous Plants and the Symptoms They Produce. Bot. Gaz., vol. 14, p. 180. 1889.

Sayre, L. E. Loco Weed. Amer. Vet. Rev., vol. 11, p. 558. 1887.