AMENTACEÆ.
The Oak (Quercus sp.). Injury to stock from the Oak has been due in the first place to the leaves, and in the second to the acorns. In regard to the leaves no injury appears to have been recorded in Britain, but Cornevin devotes attention only to poisoning by the leaves, which in special circumstances have caused serious accidents to animals which have eaten them. In France, cattle taken to the forests for grazing purposes browse on the young shoots and leaves of the oak, and after some days there arises a trouble long known as Mal de Brou or Maladie des Bois, which may end fatally, sometimes even in 24 hours (see Symptoms below). A case was also reported from Nebraska in 1903, ten head of cattle having apparently died from eating oak leaves, the trimmings from trees. The stomachs were full of the leaves, and the intestines had the appearance of being burned in places. There was no evidence of impaction. When the cut branches were removed no more cattle were lost.
Serious losses have been caused through the ingestion of acorns by young cattle not over about two years old, the years 1808, 1870, 1884, and 1900 being especially noteworthy in this respect. Cattle over three years old have seldom been affected, while sheep and pigs, if not immune to “acorn poisoning,” are but slightly affected. Müller, however, states that horses, cattle, sheep, and goats are affected; 9 quarts (10 litres) taken in four days were sufficient to cause poisoning in the case of a bullock. It is believed by some observers that half-ripe acorns—e.g. acorns which may drop owing to drought—are more injurious than thoroughly ripened acorns.
Some authorities appear to be of the opinion that “acorn poisoning” is not actually poisoning, but a serious form of indigestion. If this be so the symptoms must be regarded as exceedingly severe. There is no doubt that “acorn poisoning” is not well understood, but a great deal has been observed and written on the subject, and there is clear evidence that acorns may reasonably be held to be poisonous. It must be pointed out, however, that the poisoning does not usually follow on the consumption of acorns in small quantities, but is commonly due to full meals of acorns taken in periods when there is a dearth of herbage. By proper preparation and storage acorns have been converted into a most useful food for horses, cattle and sheep (Jour. Bd. Agric., Sept. 1914 and Feb. 1916, and Leaflet No. 291 of the Bd. Agric., The Food Value of Acorns, Horse-Chestnuts and Beech Mast). In Germany it has been found that acorns fed to fowls caused diminished egg-laying, which finally ceased, while the yolks of eggs laid were discoloured a dirty brown (Jour. Bd. Agric., Dec. 1915, p. 902).
Toxic Principle. The facts as to acorn poisoning and oak-leaf poisoning are not clearly known, and the actual toxic substance is similarly not certainly known. It is probable, however, that it consists of Tannin, or substances which give rise to Tannin.
Symptoms. In relation to Maladie des Bois due to leaves, Cornevin gives the symptoms as loss of appetite; less (and more difficult) rumination; constipation, which increases; lying down, animals looking at their flank as in colic, followed by rising and attempts to urinate, with passing of rosy-coloured liquid in jets; loss of milk production, which may drop to nothing; fever, trembling, enfeebled condition.
Three or four days after the commencement of illness rumination is completely suspended; there is stamping of the feet, colic, retracted stomach, pulse hard, heart agitated, accelerated respiration, violent muscular shocks, and frequent urination. The urine is always dark in colour, but varies from clear red to dark black, nut-brown being usual. Cases are only serious when a fœtid, frothy, and abundant dysentery succeeds constipation, in which case there is rapid emaciation and death.
Usually the course of the illness is not rapid; but occasionally there is immediate and bloody urination with violent colic and sometimes intestinal hæmorrhage, death occurring in 24 hours.
In poisoning by acorns there is progressive wasting, entire loss of appetite, diarrhœa, discharge of an excessive quantity of pale urine, sore places inside the mouth, discharge from the nostrils, and also from the eyes, which are always sunken, giving the animal a peculiar haggard expression. There is no fever; on the contrary, the temperature is commonly below normal, though in some cases stated to be above normal.
Müller remarks on the severe constipation, followed by dysenteric diarrhœa, caused by acorns, especially when eaten in the half-ripe condition, horses, cattle, sheep, and goats being affected.
The experimental poisoning of a young steer and a young sheep by fully ripe acorns was described in 1871 (Jour. R.A.S.E., 1871). In the steer the symptoms were a semi-conscious condition, weak pulse, pallid membranes, cold surface of body, torpid bowels, slow breathing, twitchings of muscles, and a disposition to maintain a recumbent position. Inflammation was entirely absent. The symptoms increased in severity day by day; there ensued a copious flow of colourless urine; a mucopurulent discharge from the eyes and nostrils. No impairment of health followed the feeding of acorns to the sheep.
Thorburn (Veterinary Journal, Feb., 1902) mentions loss of appetite, grunting, disinclination to move, prostration, icy coldness of extremities, very rapid emaciation (this sometimes was particularly noticeable), pulse very small and weak (in some cases almost imperceptible), temperature high (105° to 107° F.,) and constipation succeeded by watery diarrhœa.
Brookes and Yeomans described (Veterinary Journal, 1912) an instance in which 30 animals were affected and 9 died. The chief symptoms were a dull and depressed appearance, entire absence of appetite and rumination, a weak feeble pulse, subnormal temperature and disinclination to move. Three cases showed a mucous and blood-tinged discharge from the nostrils and anus, and these all died, one eight days after being seen and the other two the day afterwards. Obstinate stoppage was noticeable in all cases, and the fæces were inky black, stinking and very thick. Yeomans observed similar symptoms of acute digestive disturbance; later the eyes had a sunken appearance, diarrhœa set in, the fæces being dark coloured, offensive and bloodstained. The temperature was at first normal and later subnormal, and in fatal cases death took place in from 3 to 7 days.
REFERENCES.
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