120 ABSTRACTS.

FORAGE POISONING.

THE authors of this article have had the opportunity to make experimental investigations in a considerable number of outbreaks of disease attributed to forage poisoning, but in many cases the suspected forage was fed to experimental horses with n~gative results, and attempts to isolate the causa­tive factor also failed, even in some cases in which ingestion experiments produced the disease.

Veterinary practitioners and stockmen of wide experience were consulted, and the prevailing impression among them appeared to be that forage poisoning was caused by mouldy or inferior feeding stuffs. In one instance, however, forage which gave a positive result by feeding was not visibly contaminated by moulds, and in other cases moulds isolated from forage supposed to be poisonous failed to produce the disease when administered to animals experimentally.

In a natural outbreak of forage poisoning in horses the authors obtained an oat hay which caused clinical forage poisoning in ingestion experiments.

The oat forage was moved to the Experiment Station, and it was there found that both the straw and the grain produced clinical forage poisoning in horses and mules to which they were fed. Water in which the grain and straw had been immersed also infected horses which drank it. Chicken freces obtained from the oat straw after threshing also produced the disease in a horse, but such freces from other sources when used as a control had no effect. Chickens, rabbits, guinea-pigs, swine, sheep, and goats freely consumed the poisonous oat grain without noticeable effect.

Two barrels of the oat hay in question were kept for about two years, and clinical forage poisoning was produced in horses that were allowed to drink water in which this oat hay had been immersed.

In 1916 Buckley and Shippen proved that the Bacillus botulinus is patho­genic for the horse, and they noted clinical and anatomical resemblance between Bacillus botulinus intoxication artificially induced in horses and sporadic forage poisoning. They found that effects were produced in horses by administering 2 cc. of broth culture of the bacillus by the mouth or '1 cc. subcutaneously. They also reported that chickens were not noticeably affected after the ingestion of broth cultures of the bacillus, but that the freces from chickens thus fed proved capable of inducing fatal intoxication with the clinical features of forage poisoning when fed to horses.

From the internal organs of a horse which died after drinking the poisonons oat hay water previously mentioned numerous cultures were made in different media under conditions favourable for the development of the Bacillus botulinus. Samples of oat water direct from the barrel were also employed in the same way. From the crecal contents of a horse (No. 91) which died after drinking the oat water a Gram-positive, anrerobic, sporulating, rod-shaped organism resembling the Bacillus botulinus in morphology and cultural characters was isolated. '2 cc. of a broth culture of this bacillus proved fatal when administered to a guinea-pig per os.

A horse (No. 94) was given 4 cc. of broth culture of the organism mixed with ordinary feed on the 14th February 1917. The animal remained apparently well until the fifth day afterwards, when there was manifest paresis of the pharynx and marked general weakness. Post-mortem examination of this horse revealed hremorrhagic lesions in the outer wall of the small intestine, and numerous punctate hremorrhages and highly congested 'areas on the mucous membrane.

,ABSTRACTS, 121

From the crecum of the preceding horse (No, 94) an anrerobic organism similar to the one used to infect the animal was cultivated, and broth culture of this organism was again proved to be fatal to a guinea-pig when administered by the mouth,

Serum obtained from a goat immunised with Bacillus botulinus was found <:apable of preventing the death of guinea-pigs which were given '05 cc. of unfiltered Bacillus botulinus broth culture per os on the following day, while a control guinea-pig that received the same amount of culture but no serum died in about twenty·four hours.

Similar experiments showed that the botulism antitoxin protected guinea­pigs against inoculation with a culture of the organism isolated from the crecum of horse No. 91.

On 6th March 1917 two horses (Nos. 98 and 99) were given, mixed with their feed, 2 cc. of unfiltered broth culture of the anrerobic organism isolated from the crecum of horse No. 91. These animals remained perfectly healthy until the morning of 8th March, when they were found in a decumbent and moribund condition. One of the horses died at 3 P.M. on the 8th March and the other on the following morning,

Three horses (Nos. 1002, 1003, and 1004) received two prophylactic injections of botulism antitoxin followed by 4 cc. (in doses of I and 3 cc. with an interval of nine days) of broth culture of the anrerobic organism isolated from the crecum of horse No. 91 in 1000 grammes of good oats. Mule No. 105 received the same amount of culture but no serum.

The mule showed a marked resistance, and continued to feed for about nine days after the ingestion of I cc. of the broth culture, but after the dose of 3 cc. death occurred in forty-eight hours. The three serum-treated horses remained apparently healthy and were released after thirty days observation.

An anrerobic organism resembling Bacillus botulinus was obtained in culture from the stomach of mule No. 105, and it was proved to be fatal to guinea-pigs when administered by the mouth in '5 cc. doses of broth culture.

To ascertain the effect of a sterile culture filtrate of the organism isolated from the crecum of horse No. 9 I and its serological relation to Bacillus botulinus, seven horses (Nos. 1005 to 101 I) were injected with botulism antotoxin, and twenty-five hours later were given 2 cc. each of the filtered broth culture mixed WIth oats.

Another horse (No. 104) received the same amount of the filtrate at the same time but was not given any serum.

Four days after it ingested the filtrate the control horse (No. 104) showed marked salivation and paralysis of the pharynx. The symptoms had set in suddenly and they developed rapidly, death occurring on the seventh day. The serum-treated horses remained healthy and were released in thirty days.

From water in which some of the oat hay was immersed a similar organism resembling Bacillus botulinus was isolated, and it was tested on guinea-pigs to determine its relation, if any, to Bacillus botulinus. These experiments showed that serum from a sheep immunised with the Bacillus botulinus protected guinea-pigs against· 1 cc. of culture of this organism given per os, while a control guinea-pig succumbed in forty hours.

Similar immune serum obtained from a cow was proved to have the same effect.

On 20th March a horse (No. 1012) was given a prophylactic injection of anti-botulism serum, and on the following day that animal and two other horses (Nos. 107 and 112) were each given 2 cc. of broth culture of the organism isolated from the oat hay.

On the 25th March the horse (No. 107) was dull and stupid, with a noticeable impairment of the organs of deglutition and profuse salivation. Muscular weakness rapidly developed, and the animal became permanently decumbent. Death occurred on the night of 27th March. Up to this time

H

IZZ ABSTRACTS.

the other two horses appeared normal. On 30th March it was noticed that horse No. lIZ fed slowly and apparently with some difficulty, although the appetite was not impaired. Attempts to drink were continuous, but the water was returned through the nose. The horse lost condition after this, and it died during the night of 5th April. On 30th March a transient reaction was noticed in horse No. 101Z and the animal was given a dose of antitoxic serum. The symptoms soon subsided, and the horse afterwards remained well and was released on 30th April.

In another experiment four horses were given a dose of botulinus anti­toxin, and on the following day these and three control horses were each given Z cc. of filtered broth culture of the bacillus isolated from the poisonous oats. The three control horses all died, one on 31st March, another on the znd April, and the third on 7th April. The four serum-treated horses displayed no symptoms and were released after thirty days.

In the case of an outbreak of forage poisoning in mules in Carroll County, Kentucky, feeding experiments proved that corn ensilage was the cause of the trouble, and from this ensilage there was isolated an amerobic, Gram­positive bacillus which resembled the Bacillus botulinus in cultural and morphological characters. Cultures of this organism were found capable of setting up the symptoms of forage poisoning in horses and mules, and botulinus antitoxin from a goat was again proved to protect guinea-pigs and horses against the administration of culture. (R Graham, A. L. Brueckner, and R. L. Pontius, Journal 0/ the American Veterinary Medical Association, Vol. LIlL, 1918, p. 161.)

IMMUNISATION AGAINST BLACK LEG BY MEANS OF FILTRATE OF ARTIFICIAL CULTURES OF THE BACILLUS.

IT was Arloing, Cornevin, and Thomas, who, in 1880, first discovered that animals could be protected against black leg by a subcutaneous injection of minimal doses of fluid from a black leg tumour and also by an intravenous or intratracheal injection of the virus. These methods, however, were aban­doned as beingioo dangerous or too complicated to be of practical value. In 1883 the same French sCIentists described a method of vaccination which ever since has been practised largely in France, Switzerland, and other countries. In this method two vaccines of different virulence are employed: the first or weaker vaccine is prepared by exposing the dried juice obtained from a black leg tumour to a temperature of 100°-104° C. for six hours, and the second or stronger vaccine by exposing it for the same length of time to a temperature of 85°-90° C. The under-surface of the tail is the seat of inoculation, and the operation is attended 'with some difficulty owing to the density of the subcutaneous tissue of the part.

Kitt, in 1888, published a simplified method of vaccination, in which a single vaccine is prepared by heating virulent muscle-powder at a tem­perature of 100° C. for six hours in a steam steriliser. The vaccine is injected in the shoulder region where the skin is loose. This vaccine has been used largely in Bavaria.

Norgaard, of the Bureau of Animal Industry, U.S. Department of Agri­culture, 1896-1897, also prepared a vaccine, which by a single inoculation produced 'practical immunity, and since then has been used exten­sively in the United States of America. Like Kitt's vaccine, this is also muscle-powder heated in an oil bath, at a temperature of 93°-94° c., and the site of injection is the side of the neck or chest.